Frequency of Atrial Arrhythmia in Hospitalized Patients with COVID-19

There is growing evidence that COVID-19 can cause cardiovascular complications. However, there are limited data on the characteristics and importance of atrial arrhythmia (AA) in patients hospitalized with COVID-19. Data from 1029 patients diagnosed with of COVID-19 and admitted to Columbia University Medical Center between March 1st and April 15th 2020 were analyzed. The diagnosis of AA was confirmed by 12 lead electrocardiographic recordings, 24hour telemetry recordings and implantable device interrogations. Patients' history, biomarkers and hospital course were reviewed. Outcomes of death, intubation and discharge were assessed. Of 1029 patients, 82 (8%) were diagnosed with AA. Out of the 82 patients with AA. Of the AA patients, new-onset AA was seen in 46 (56%) patients, recurrent paroxysmal and chronic persistent were diagnosed in 16 (20%) and 20 (24%) individuals, respectively. Sixty-five percent of the patients diagnosed with AA (n=53) died. Patients diagnosed with AA had significantly higher mortality compared to those without AA (65% vs. 21%; p < 0.001). Predictors of mortality were older age (Odds Ratio (OR) =1.12, [95% Confidence Interval (CI), 1.04 to 1.22]); male gender (OR=6.4 [95% CI, 1.3 to 32]); azithromycin use (OR=13.4 [95% CI, 2.14 to 84]); and higher D-dimer levels (OR=2.8 [95% CI, 1.1 to7.3]). In conclusion, patients diagnosed with AA had 3.1 times significant increase in mortality rate versus patients without diagnosis of AA in COVID-19 patients. Older age, male gender, azithromycin use and higher baseline D-dimer levels were predictors of mortality.

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Worldwide Survey of COVID-19 Associated Arrhythmias

Background - COVID-19 has led to over 1 million deaths worldwide and has been associated with cardiac complications including cardiac arrhythmias. The incidence and pathophysiology of these manifestations remain elusive. In this worldwide survey of patients hospitalized with COVID-19 who developed cardiac arrhythmias, we describe clinical characteristics associated with various arrhythmias, as well as global differences in modulations of routine electrophysiology practice during the pandemic.

Methods - We conducted a retrospective analysis of patients hospitalized with COVID-19 infection worldwide with and without incident cardiac arrhythmias. Patients with documented atrial fibrillation (AF), atrial flutter (AFL), supraventricular tachycardia (SVT), non-sustained or sustained ventricular tachycardia (VT), ventricular fibrillation (VF), atrioventricular block (AVB), or marked sinus bradycardia (HR<40bpm) were classified as having arrhythmia. De-identified data was provided by each institution and analyzed.

Results - Data was collected for 4,526 patients across 4 continents and 12 countries, 827 of whom had an arrhythmia. Cardiac comorbidities were common in patients with arrhythmia: 69% had hypertension, 42% diabetes mellitus, 30% had heart failure and 24% coronary artery disease. Most had no prior history of arrhythmia. Of those who did develop an arrhythmia, the majority (81.8%) developed atrial arrhythmias, 20.7% developed ventricular arrhythmias, and 22.6% had bradyarrhythmia. Regional differences suggested a lower incidence of AF in Asia compared to other continents (34% vs. 63%). Most patients in in North America and Europe received hydroxychloroquine, though the frequency of hydroxychloroquine therapy was constant across arrhythmia types. Forty-three percent of patients who developed arrhythmia were mechanically ventilated and 51% survived to hospital discharge. Many institutions reported drastic decreases in electrophysiology procedures performed.

Conclusions - Cardiac arrhythmias are common and associated with high morbidity and mortality among patients hospitalized with COVID-19 infection. There were significant regional variations in the types of arrhythmias and treatment approaches.

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Metformin Is Associated with a Lower Risk of Atrial Fibrillation and Ventricular Arrhythmias Compared to Sulfonylureas: An Observational Study

Background - Type 2 diabetes (DM2) is one of the most common chronic disorders worldwide and is an important cause of cardiovascular disease. Studies investigating the risk of atrial and ventricular arrhythmias in diabetic patients taking different oral diabetes medications are sparse.

Methods - We used IBM MarketScan® Medicare Supplemental Database to examine the risk of arrhythmias for patients on different oral diabetes medications by propensity score matching.

Results - We found that patients on metformin monotherapy had significantly reduced risk of atrial arrhythmias, including atrial fibrillation, compared to monotherapy with DPP4 or TZD medications. Patients on metformin monotherapy had significantly reduced risk of atrial arrhythmias, ventricular arrhythmias, and bradycardia compared to monotherapy with sulfonylureas. Combination therapy with sulfonylureas and metformin had an increased risk of atrial arrhythmias compared to some other combinations.

Conclusions - Different oral diabetes medications have significantly different long-term risk of arrhythmia. Specifically, metformin is associated with reduced risk of atrial fibrillation and ventricular arrhythmias compared to sulfonylureas.

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Integrated electrophysiology care for patients with heart failure: An envisioned future

Heart failure (HF) is a chronic, progressive, and complex disease that is increasing in prevalence with a projected 46% increase from 2012 to 2030. 

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Frequent hospital admissions have made HF one of the leading causes of health care expenditures, costing the system more than 30 billion US dollars a year. 

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Many of these patients have cardiac implantable electronic devices (CIEDs), wearable devices, and atrial and ventricular arrhythmias. There is an increasing focus on how to best manage these patients, with the recognition that an integrated care model is optimal.

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EVOLUTION OF RISK STRATIFICATION AND SUDDEN DEATH PREVENTION IN HYPERTROPHIC CARDIOMYOPATHY: 20 YEARS WITH THE IMPLANTABLE CARDIOVERTER-DEFIBRILLATOR

Hypertrophic cardiomyopathy (HCM) is a relatively common inherited myocardial disorder, once regarded as largely untreatable with ominous prognosis and most visibly as a common cause of sudden death (SD) in the young. Over the last several years, HCM has been transformed into a contemporary treatable disease with management options that significantly alter the clinical course. With the use of implantable cardioverter-defibrillators (ICDs) in the HCM patient population, a new paradigm has emerged, with primary prevention device therapy reliably terminating potentially lethal ventricular tachyarrhythmias (3%–4% per year) and being largely responsible for a >10-fold decrease in disease-related mortality (to 0.5% per year), independent of age. A guideline-based clinical risk stratification algorithm has evolved, including variables identified with cardiac magnetic resonance. One or more risk markers judged major and relevant within a patient’s clinical profile can be considered sufficient to recommend a primary prevention implant (associated with a measure of physician judgment and shared decision-making). ICD decisions using the individual risk marker strategy have been associated with 95% sensitivity for identifying patients who subsequently experienced appropriate ICD therapy, albeit often delayed substantially for >5 or >10 years after implant, but without heart failure deterioration or death following device intervention. A rigid mathematically derived statistical risk model proposed by the European Society of Cardiology is associated with low sensitivity (ie, 33%) for predicting SD events. Introduction of prophylactically inserted ICDs to HCM 20 years ago has significantly altered the clinical course and landscape of this disease. SD prevention has reduced HCM mortality significantly, making preservation of life and potential for normal longevity a reality for most HCM patients.

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Admission Cardiac Diagnostic Testing with Electrocardiography and Troponin Measurement Prognosticates Increased 30‐Day Mortality in COVID‐19

Background

Cardiovascular involvement in coronavirus disease 2019 (COVID‐19) is common and leads to worsened mortality. Diagnostic cardiovascular studies may be helpful for resource appropriation and identifying patients at increased risk for death.

Methods and Results

We analyzed 887 patients (aged 64±17 years) admitted with COVID‐19 from March 1 to April 3, 2020 in New York City with 12 lead electrocardiography within 2 days of diagnosis. Demographics, comorbidities, and laboratory testing, including high sensitivity cardiac troponin T (hs‐cTnT), were abstracted. At 30 days follow‐up, 556 patients (63%) were living without requiring mechanical ventilation, 123 (14%) were living and required mechanical ventilation, and 203 (23%) had expired. Electrocardiography findings included atrial fibrillation or atrial flutter (AF/AFL) in 46 (5%) and ST‐T wave changes in 306 (38%). 27 (59%) patients with AF/AFL expired as compared to 181 (21%) of 841 with other non‐life‐threatening rhythms (P<0.001). Multivariable analysis incorporating age, comorbidities, AF/AFL, QRS abnormalities, and ST‐T wave changes, and initial hs‐cTnT ≥20 ng/L showed that increased age (HR 1.04/year), elevated hs‐cTnT (HR 4.57), AF/AFL (HR 2.07), and a history of coronary artery disease (HR 1.56) and active cancer (HR 1.87) were associated with increased mortality.

Conclusions

Myocardial injury with hs‐cTnT ≥20 ng/L, in addition to cardiac conduction perturbations, especially AF/AFL, upon hospital admission for COVID‐19 infection is associated with markedly increased risk for mortality than either diagnostic abnormality alone.

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Theoretical models and computational analysis of action potential dispersion for cardiac arrhythmia risk stratification

Reentrant cardiac arrhythmias such as atrial fibrillation (AF) and ventricular fibrillation (VF) are common cardiac arrhythmias that account for substantial morbidity and mortality throughout the world. However, the mechanisms and optimal ablation treatment strategies for such arrhythmias are still unclear. Using 2D optical mapping of a mouse model with AF and VF, we have identified regional heterogeneity of the action potential duration (APD) in the atria and ventricles of the heart as key drivers for the initiation and persistence of reentry. The purpose of this paper is to discuss theoretical patterns of dispersion, demonstrate patterns of dispersion seen in our mouse model and discuss the computational analysis of APD dispersion patterns. These analyses and discussions may lead to better understanding of dispersion patterns in patients with these arrhythmias, as well as help comprehend whether and how reducing …

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High-density Grid Technology Aids in the Visualization of Purkinje Potentials in Fascicular Ventricular Tachycardia

A 71-year-old man with atrial fibrillation (AF), ischemic cardiomyopathy, and ventricular tachycardia (VT) presented having experienced implantable cardioverter-defibrillator (ICD) shocks. He had been previously treated with amiodarone and ICD placement for VT. His last episode of VT was several years prior to admission. About two months before admission, several appropriate shocks were recorded. Despite an increase in amiodarone, in subsequent weeks, he received several additional shocks with syncope. He was hospitalized and an unchanged ejection fraction of 35%, patent bypass grafts, and no new coronary disease were documented. He was then transferred to our institution.

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High-density Grid Mapping of Micro-and Macro-reentrant Left Atrial Arrhythmias

Dr. Wan has served on the steering committee for Medtronic and Boston Scientific. Dr. Saluja has served as a consultant to Abbott and BioSense Webster. Dr. Biviano has served as a medical advisory board member for Abbott, BioSense Webster, and Boston Scientific. The other authors report no conflicts of interest for the published content.

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Management of Arrhythmias Associated with COVID-19

Personalized care while balancing risk/benefit of medical or invasive therapy is necessary to improve care of patients with arrhythmias. Providers must provide thorough follow-up care and use necessary precaution while caring for COVID-19 patients.

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Clinical and cardiac characteristics of COVID‐19 mortalities in a diverse New York City Cohort

Introduction

Electrocardiographic characteristics in COVID‐19‐related mortality have not yet been reported, particularly in racial/ethnic minorities.

Methods and Results

We reviewed demographics, laboratory and cardiac tests, medications, and cardiac rhythm proximate to death or initiation of comfort care for patients hospitalized with a positive SARS‐CoV‐2 reverse‐transcriptase polymerase chain reaction in three New York City hospitals between March 1 and April 3, 2020 who died. We described clinical characteristics and compared factors contributing toward arrhythmic versus nonarrhythmic death. Of 1258 patients screened, 133 died and were enrolled. Of these, 55.6% (74/133) were male, 69.9% (93/133) were racial/ethnic minorities, and 88.0% (117/133) had cardiovascular disease. The last cardiac rhythm recorded was VT or fibrillation in 5.3% (7/133), pulseless electrical activity in 7.5% (10/133), unspecified bradycardia in 0.8% (1/133), and asystole in 26.3% (35/133). Most 74.4% (99/133) died receiving comfort measures only. The most common abnormalities on admission electrocardiogram included abnormal QRS axis (25.8%), atrial fibrillation/flutter (14.3%), atrial ectopy (12.0%), and right bundle branch block (11.9%). During hospitalization, an additional 17.6% developed atrial ectopy, 14.7% ventricular ectopy, 10.1% atrial fibrillation/flutter, and 7.8% a right ventricular abnormality. Arrhythmic death was confirmed or suspected in 8.3% (11/133) associated with age, coronary artery disease, asthma, vasopressor use, longer admission corrected QT interval, and left bundle branch block (LBBB).

Conclusions

Conduction, rhythm, and electrocardiographic abnormalities were common during COVID‐19‐related hospitalization. Arrhythmic death was associated with age, coronary artery disease, asthma, longer admission corrected QT interval, LBBB, ventricular ectopy, and usage of vasopressors. Most died receiving comfort measures.

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The Effect of Radiofrequency Catheter Ablation of Typical Atrial Flutter on Cardiac Chambers' Size and Function

Introduction: Cavo-tricuspid isthmus (CTI) dependent atrial flutter (AFL) is one of the most common atrial arrhythmias involving the right atrium (RA) for which radiofrequency catheter ablation has been widely used as a therapy of choice. However, there is limited data on the effect of this intervention on cardiac size and function.

Hypothesis: CTI dependent ablation for patients with AFL will improve tricuspid valve function, biatrial enlargement, and ventricular function.

Methods: A retrospective study was conducted on 468 patients who underwent CTI dependent ablation for clinical typical AFL at a single institution between 2010 and 2019. After patients with congenital or rheumatic heart disease, heart transplant recipients, or those without baseline echocardiogram were excluded, 211 patients remained in the analysis. Echocardiographic data were analyzed at baseline prior to ablation, and at early follow-up within 1-year post-ablation. Follow-up echocardiographic data was available for 130 patients.

Results: Of the 211 patients with CTI-AFL, 200 had typical counterclockwise flutter. The mean age was 64.2±12.1 years old with 12% (n=26) female. The average left ventricular (LV) ejection fraction (EF) significantly improved on follow-up echo (45.55±14.26 to 49±14.4%, p=0.0075), of which 63 (48%) patients had an improvement in EF of 5% or more and 19 (25%) patients had an increased EF of 20% or more. The prevalence of moderate to severe tricuspid regurgitation (TR) was 24% (n=50) at baseline and 18% (n=22) at follow-up with no significant difference (p=0.27). However, 30% (n=39) of the patients had one grade or more improvement in their TR within the 1-year follow-up. Echocardiography also showed improvement of RA size in 48.6%, and left atrial (LA) size in 48.2% of the patients.

Conclusions: Patients who underwent CTI dependent AFL ablation showed an improvement in cardiac size and function at follow-up evaluation. Although longer-term results are unknown, these findings suggest that restoration of sinus rhythm from atrial flutter is associated with improvement in TR severity, RA size, LA size, and LVEF.

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Outcome of Radiofrequency Catheter Ablation of Cavo-tricuspid Isthmus Dependent Flutter in Patients With Adult Congenital Heart Disease

Introduction: Both typical cavo-tricuspid isthmus (CTI) dependent (or its equivalent) and atypical atrial flutter (AFL) are common in adults with congenital heart disease (CHD) either due to its inherent cardiac anatomy or as a result of prior surgical procedures. Radiofrequency catheter ablation is routinely used as a therapeutic option.

Hypothesis: Patients with CHD will have an improvement in systemic ventricular ejection fraction and a decreased incidence of atrial arrhythmias after ablation.

Methods: A retrospective study was conducted on 99 patients with CHD who underwent ablation for clinical AFL at a single institution between 2010 and 2019. Of these patients, 62 had CTI-AFL. The 2 patients with unspecified CHD were excluded. CHD was divided into 3 categories according to the American College of Cardiology Task Force 1 of the 32nd Bethesda Conference - simple, moderate severity, and great complexity lesions. Outcomes of ablation at 1 year follow up were assessed.

Results: Typical counterclockwise CTI-AFL was seen in 50 patients. The mean age was 49.1±13.6 years old with 29 (48.3%) females. Of the 60 patients, 35% (n=21) had simple lesions, 51.7% (n=31) had moderate lesions, and 13.3% (n=8) had great complexity lesions. The mean left or systemic ventricular ejection fraction (EF) significantly improved on follow-up echo among patients with simple CHD (49.1±13.1 to 56.5±4.7%, p=0.018) and moderate CHD (49.5±14.9 to 54±8.5%, p=0.02), but did not change among patients with great complexity CHD (52.5±6 to 52.5±9.25%, p=0.9). There was a significantly increased incidence of atrial fibrillation (9.5% vs. 16.1% vs. 50%, p=0.04) post ablation among simple, moderate, and great complexity lesions, respectively, but no significant difference in the recurrence rate of atrial flutter (p=0.3).

Conclusions: Patients who underwent CTI-AFL ablation showed an improvement in EF in patients with simple and moderate CHD. There was also a significantly increased incidence in the development of atrial fibrillation post ablation in CHD with great complexity compared to simple or moderate CHD.

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Outcomes of Radiofrequency Catheter Ablation of Atrial Arrhythmias in Lung Transplant Recipients

Introduction: Atrial arrhythmias (AA) are common after lung transplant (LT) and may impact overall mortality. The majority of arrhythmias tend to be organized flutter, amenable to ablation; however the data is limited.

Hypothesis: The purpose of this study was to investigate the outcomes of radiofrequency catheter ablation of AA in LT recipients.

Methods: All LT recipients undergoing electrophysiology study at our institution between 2011-2018 were retrospectively reviewed. A total of 20 atrial ablations were identified in 16 patients. Mean follow-up was 4 ± 2.9 years.

Results: Overall, mean age was 55 ± 13 years, 63% were male, 63% were status post bilateral (vs. single) LT, and mean LVEF was 57%. Transplant indications included interstitial lung disease (44%), COPD (19%), and cystic fibrosis (19%). Antiarrhythmics and beta blockers were used in 44% and 75%, respectively. Mean time from transplant to first ablation was 2.7 years. Of 20 ablations, macro-reentrant flutter (75%) and focal atrial tachycardia (15%) were common, particularly in double LT recipients (Figure). The most common ablation sites were pulmonary vein anastomosis/left atrial ridge (60%), mitral annulus (35%) and left atrial roof (30%). Restoration of sinus rhythm occurred in 19 of 20 procedures and only one complication occurred (e.g. small pericardial effusion without tamponade). Arrhythmia recurred in 10 (63%) patients, however, most were managed conservatively. Repeat ablation was needed in 4 patients, of which AAs originated from different locations. Beta blocker use was associated with a lower risk of SVT recurrence (p=0.04). Reduced LVEF and longer time to procedure post-transplant were associated with repeat ablation (p<0.05).

Conclusions: The majority of AAs in LT recipients are atrial flutter originating near the pulmonary vein anastomosis sites. Despite a high immediate procedural success rate, recurrence is high and 25% of patients require multiple ablation attempts.

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Digital Health and the Care of the Patient With Arrhythmia: What Every Electrophysiologist Needs to Know

The field of cardiac electrophysiology has been on the cutting edge of advanced digital technologies for many years. More recently, medical device development through traditional clinical trials has been supplemented by direct to consumer products with advancement of wearables and health care apps. The rapid growth of innovation along with the mega-data generated has created challenges and opportunities. This review summarizes the regulatory landscape, applications to clinical practice, opportunities for virtual clinical trials, the use of artificial intelligence to streamline and interpret data, and integration into the electronic medical records and medical practice. Preparation of the new generation of physicians, guidance and promotion by professional societies, and advancement of research in the interpretation and application of big data and the impact of digital technologies on health outcomes will help to advance the adoption and the future of digital health care.

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Cardiac electrophysiology consultative experience at the epicenter of the COVID-19 pandemic in the United States

Background

The COVID-19 pandemic has greatly altered the practice of cardiac electrophysiology around the world for the foreseeable future. Professional organizations have provided guidance for practitioners, but real-world examples of the consults and responsibilities cardiac electrophysiologists face during a surge of COVID-19 patients is lacking.

Methods

In this observational case series we report on 29 consecutive inpatient electrophysiology consultations at a major academic medical center in New York City, the epicenter of the pandemic in the United States, during a 2 week period from March 30-April 12, 2020, when 80% of hospital beds were occupied by COVID-19 patients, and the New York City metropolitan area accounted for 10% of COVID-19 cases worldwide.

Results

Reasons for consultation included: Atrial tachyarrhythmia (31%), cardiac implantable electronic device management (28%), bradycardia (14%), QTc prolongation (10%), ventricular arrhythmia (7%), post-transcatheter aortic valve replacement conduction abnormality (3.5%), ventricular pre-excitation (3.5%), and paroxysmal supraventricular tachycardia (3.5%). Twenty-four patients (86%) were positive for COVID-19 by nasopharyngeal swab. All elective procedures were canceled, and only one urgent device implantation was performed. Thirteen patients (45%) required in-person evaluation and the remainder were managed remotely.

Conclusion

Our experience shows that the application of a massive alteration in workflow and personnel forced by the pandemic allowed our team to efficiently address the intersection of COVID-19 with a range of electrophysiology issues. This experience will prove useful as guidance for emerging hot spots or areas affected by future waves of the pandemic.

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Slow uniform electrical activation during sinus rhythm is an indicator of reentrant VT isthmus location and orientation in an experimental model of myocardial infarction

Background

To validate the predictability of reentrant circuit isthmus locations without ventricular tachycardia (VT) induction during high-definition mapping, we used computer methods to analyse sinus rhythm activation in experiments where isthmus location was subsequently verified by mapping reentrant VT circuits.

Method

In 21 experiments using a canine postinfarction model, bipolar electrograms were obtained from 196-312 recordings with 4mm spacing in the epicardial border zone during sinus rhythm and during VT. From computerized electrical activation maps of the reentrant circuit, areas of conduction block were determined and the isthmus was localized. A linear regression was computed at three different locations about the reentry isthmus using sinus rhythm electrogram activation data. From the regression analysis, the uniformity, a measure of the constancy at which the wavefront propagates, and the activation gradient, a measure that may approximate wavefront speed, were computed. The purpose was to test the hypothesis that the isthmus locates in a region of slow uniform activation bounded by areas of electrical discontinuity.

Results

Based on the regression parameters, sinus rhythm activation along the isthmus near its exit proceeded uniformly (mean r2= 0.95±0.05) and with a low magnitude gradient (mean 0.37±0.10mm/ms). Perpendicular to the isthmus long-axis across its boundaries, the activation wavefront propagated much less uniformly (mean r2= 0.76±0.24) although of similar gradient (mean 0.38±0.23mm/ms). In the opposite direction from the exit, at the isthmus entrance, there was also less uniformity (mean r2= 0.80±0.22) but a larger magnitude gradient (mean 0.50±0.25mm/ms). A theoretical ablation line drawn perpendicular to the last sinus rhythm activation site along the isthmus long-axis was predicted to prevent VT reinduction. Anatomical conduction block occurred in 7/21 experiments, but comprised only small portions of the isthmus lateral boundaries; thus detection of sinus rhythm conduction block alone was insufficient to entirely define the VT isthmus.

Conclusions

Uniform activation with a low magnitude gradient during sinus rhythm is present at the VT isthmus exit location but there is less uniformity across the isthmus lateral boundaries and at isthmus entrance locations. These factors may be useful to verify any proposed VT isthmus location, reducing the need for VT induction to ablate the isthmus. Measured computerized values similar to those determined herein could therefore be assistive to sharpen specificity when applying sinus rhythm mapping to localize EP catheter ablation sites.

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Increased Incidence of Chronic Kidney Injury in African Americans Following Cardiac Transplantation

Objectives

This study examined whether African American race was associated with an elevated risk of chronic kidney disease (CKD) post-cardiac transplantation.

Background

CKD often occurs after cardiac transplantation and may require renal replacement therapy (RRT) or renal transplant. African American patients have a higher risk for kidney disease as well as worse post-cardiac transplant morbidity and mortality. It is unclear, however, if there is a propensity for African Americans to develop CKD after cardiac transplant.

Methods

The Institutional Review Board of Columbia University Medical Center approved the retrospective study of 151 adults (57 African American and 94 non-African American) who underwent single-organ heart transplant from 2013 to 2016. The primary outcome was a decrease in estimated glomerular filtration rate (eGFR), development of CKD, and end-stage renal disease (ESRD) requiring RRT after 2 years.

Results

African American patients had a significant decline in eGFR post-cardiac transplant compared to non-African American patients (− 34 ± 6 vs. − 20 ± 4 mL/min/1.73 m2, p < 0.0006). African American patients were more likely to develop CKD stage 2 or worse (eGFR < 90 mL/min/1.73 m2) than non-African American patients (81% vs. 59%, p < 0.0005).

Conclusions

This is the first study to report that African American patients are at a significantly higher risk for eGFR decline and CKD at 2 years post-cardiac transplant. Future investigation into risk reduction is necessary for this patient population.

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Digital Health and the Care of the Arrhythmia Patient; What Every Electrophysiologist Needs to Know.

The field of cardiac electrophysiology has been on the cutting edge of advanced digital technologies for many years. More recently, medical device development through traditional clinical trials has been supplemented by direct to consumer products with advancement of wearables and healthcare apps. The rapid growth of innovation along with the mega-data generated has created challenges and opportunities. This review summarizes the regulatory landscape, applications to clinical practice, opportunities for virtual clinical trials, the use of artificial intelligence to streamline and interpret data, and integration into the electronic medical records and medical practice. Preparation of the new generation of physicians, guidance and promotion by professional societies, and advancement of research in the interpretation and application of big data and the impact of digital technologies on health outcomes will help to advance the adoption and the future of digital health care.

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Fibroblast growth factor homologous factors tune arrhythmogenic late NaV1. 5 current in calmodulin binding–deficient channels

The Ca2+-binding protein calmodulin has emerged as a pivotal player in tuning Na+ channel function, although its impact in vivo remains to be resolved. Here, we identify the role of calmodulin and the NaV1.5 interactome in regulating late Na+ current in cardiomyocytes. We created transgenic mice with cardiac-specific expression of human NaV1.5 channels with alanine substitutions for the IQ motif (IQ/AA). The mutations rendered the channels incapable of binding calmodulin to the C-terminus. The IQ/AA transgenic mice exhibited normal ventricular repolarization without arrhythmias and an absence of increased late Na+ current. In comparison, transgenic mice expressing a lidocaine-resistant (F1759A) human NaV1.5 demonstrated increased late Na+ current and prolonged repolarization in cardiomyocytes, with spontaneous arrhythmias. To determine regulatory factors that prevent late Na+ current for the IQ/AA mutant channel, we considered fibroblast growth factor homologous factors (FHFs), which are within the NaV1.5 proteomic subdomain shown by proximity labeling in transgenic mice expressing NaV1.5 conjugated to ascorbate peroxidase. We found that FGF13 diminished late current of the IQ/AA but not F1759A mutant cardiomyocytes, suggesting that endogenous FHFs may serve to prevent late Na+ current in mouse cardiomyocytes. Leveraging endogenous mechanisms may furnish an alternative avenue for developing novel pharmacology that selectively blunts late Na+ current.

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The prognostic value of electrocardiogram at presentation to emergency department in patients with COVID-19

Objective

To study whether combining vital signs and electrocardiogram (ECG) analysis can improve early prognostication.

Methods

This study analyzed 1258 adults with coronavirus disease 2019 who were seen at three hospitals in New York in March and April 2020. Electrocardiograms at presentation to the emergency department were systematically read by electrophysiologists. The primary outcome was a composite of mechanical ventilation or death 48 hours from diagnosis. The prognostic value of ECG abnormalities was assessed in a model adjusted for demographics, comorbidities, and vital signs.

Results

At 48 hours, 73 of 1258 patients (5.8%) had died and 174 of 1258 (13.8%) were alive but receiving mechanical ventilation with 277 of 1258 (22.0%) patients dying by 30 days. Early development of respiratory failure was common, with 53% of all intubations occurring within 48 hours of presentation. In a multivariable logistic regression, atrial fibrillation/flutter (odds ratio [OR], 2.5; 95% CI, 1.1 to 6.2), right ventricular strain (OR, 2.7; 95% CI, 1.3 to 6.1), and ST segment abnormalities (OR, 2.4; 95% CI, 1.5 to 3.8) were associated with death or mechanical ventilation at 48 hours. In 108 patients without these ECG abnormalities and with normal respiratory vitals (rate <20 breaths/min and saturation >95%), only 5 (4.6%) died or required mechanical ventilation by 48 hours versus 68 of 216 patients (31.5%) having both ECG and respiratory vital sign abnormalities.

Conclusion

The combination of abnormal respiratory vital signs and ECG findings of atrial fibrillation/flutter, right ventricular strain, or ST segment abnormalities accurately prognosticates early deterioration in patients with coronavirus disease 2019 and may assist with patient triage.

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Cardiac arrhythmias in patients with COVID‐19

The emergence of coronavirus disease 2019 (COVID‐19), caused by the severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) has become a major global public health concern. Although SARS‐CoV‐2 causes primarily respiratory problems, concurrent cardiac injury cannot be ignored since it may be an independent predictor for adverse outcomes. Cardiac arrhythmias are often observed in patients with COVID‐19, especially in severe cases, and more likely contribute to the high risk of adverse outcomes. Arrhythmias should be regarded as one of the main complications of COVID‐19. Mechanistically, a number of ion channels can be adversely affected in COVID‐19, leading to alterations in cardiac conduction and/or repolarization properties, as well as calcium handling, which can predispose to cardiac arrhythmogenesis. In addition, several antimicrobials that are currently used as potential therapeutic agents for COVID‐19, such as chloroquine, hydroxychloroquine and azithromycin, have uncertain benefit, and yet may induce electrocardiographic QT prolongation with potential ventricular pro‐arrhythmic effects. Continuous electrocardiogram monitoring, accurate and prompt recognition of arrhythmias are important. The present review focuses on cardiac arrhythmias in patients with COVID‐19, its underlying mechanisms, and proposed preventive and therapeutic strategies.

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Indications for and findings on transthoracic echocardiography in COVID-19

Background

Despite growing evidence of cardiovascular complications associated with coronavirus disease 2019 (COVID-19), there are few data regarding the performance of transthoracic echocardiography (TTE) and the spectrum of echocardiographic findings in this disease.

Methods

A retrospective analysis was performed among adult patients admitted to a quaternary care center in New York City between March 1 and April 3, 2020. Patients were included if they underwent TTE during the hospitalization after a known positive diagnosis for COVID-19. Demographic and clinical data were obtained using chart abstraction from the electronic medical record.

Results

Of 749 patients, 72 (9.6%) underwent TTE following positive results on severe acute respiratory syndrome coronavirus-2 polymerase chain reaction testing. The most common clinical indications for TTE were concern for a major acute cardiovascular event (45.8%) and hemodynamic instability (29.2%). Although most patients had preserved biventricular function, 34.7% were found to have left ventricular ejection fractions ≤ 50%, and 13.9% had at least moderately reduced right ventricular function. Four patients had wall motion abnormalities suggestive of stress-induced cardiomyopathy. Using Spearman rank correlation, there was an inverse relationship between high-sensitivity troponin T and left ventricular ejection fraction (ρ = −0.34, P = .006). Among 20 patients with prior echocardiograms, only two (10%) had new reductions in LVEF of >10%. Clinical management was changed in eight individuals (24.2%) in whom TTE was ordered for concern for acute major cardiovascular events and three (14.3%) in whom TTE was ordered for hemodynamic evaluation.

Conclusions

This study describes the clinical indications for use and diagnostic performance of TTE, as well as findings seen on TTE, in hospitalized patients with COVID-19. In appropriately selected patients, TTE can be an invaluable tool for guiding COVID-19 clinical management.

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Feasibility of near-infrared spectroscopy as a tool for anatomical mapping of the human epicardium

Epicardial ablation is necessary for the treatment of ventricular tachycardias refractory to endocardial ablation due to arrhythmic substrates involving the epicardium. The human epicardium is composed of adipose tissue and coronary vasculature embedded on the surface and within the myocardium, which can complicate electroanatomical mapping, electrogram interpretation and ablation delivery. We propose using near-infrared spectroscopy (NIRS) to decipher adipose tissue from myocardial tissue within human hearts ex vivo. Histological measurement of epicardial adipose thickness direct correlated (R = 0.884) with the adipose contrast index. These results demonstrate the potential of NIRS integrated catheters for mapping the spatial distribution of epicardial substrates and could aid in improving guidance during epicardial ablation interventions.

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Atrial Arrhythmia in Hospitalized Patients with COVID-19

Introduction: There is growing evidence that COVID-19 can cause cardiovascular complications. However, there are limited data on the characteristics and importance of atrial arrhythmia (AA) in patients hospitalized with COVID-19. Methods: Data from 1029 patients diagnosed with of COVID-19 and admitted to Columbia University Medical Center between March 1st and April 15th 2020 were analyzed. The diagnosis of AA was confirmed by 12 lead electrocardiographic recordings, 24-hour telemetry recordings and implantable device interrogations. Patients’ history, biomarkers and hospital course were reviewed. Outcomes of death, intubation and discharge were assessed. Results: Of 1029 patients, 82 (8%) were diagnosed with AA. Out of the 82 patients with AA. Of the AA patients, new-onset AA was seen in 46 (56%) patients, recurrent paroxysmal and chronic persistent were diagnosed in 16 (20%) and 20 (24%) individuals, respectively. Sixty-five percent of the patients diagnosed with AA (n=53) died. Patients diagnosed with AA had significantly higher mortality compared to those without AA (65% vs. 21%; p < 0.001). Predictors of mortality were older age (Odds Ratio (OR) =1.12, [95% Confidence Interval (CI), 1.04 to 1.22]); male gender (OR=6.4 [95% CI, 1.3 to 32]); azithromycin use (OR=13.4 [95% CI, 2.14 to 84]); and higher D-dimer levels (OR=2.8 [95% CI, 1.1 to7.3]). Conclusions: Patients diagnosed with AA had 3.1 times significant increase in mortality rate versus patients without diagnosis of AA in COVID-19 patients. Older age, male gender, azithromycin use and higher baseline D-dimer levels were predictors of mortality.

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Non-invasive systems and methods for rendering of cardiac electromechanical activation

Systems and methods for generating an electromechanical map are disclosed herein. The methods includes obtaining ultrasound data comprising a series of consecutive image frames and radio frequency (RF) signals corresponding to the location in the heart; measuring displacements and strains based on the ultrasound data to determine an electromechanical activation in the location; converting the ultrasound data into a series of isochrone maps; and combining the series of isochrone maps to generate the electromechanical map. The electromechanical map illustrates the electromechanical activation and internal wall structures of the heart.

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Survey of current perspectives on consumer-available digital health devices for detecting atrial fibrillation

Background

Many digital health technologies capable of atrial fibrillation (AF) detection are directly available to patients. However, adaptation into clinical practice by heart rhythm healthcare practitioners (HCPs) is unclear.

Objective

To examine HCP perspectives on use of commercial technologies for AF detection and management.

Methods

We created an electronic survey for HCPs assessing practice demographics and perspectives on digital devices for AF detection and management. The survey was distributed electronically to all members of 3 heart rhythm professional societies.

Results

We received 1601 responses out of 73,563 e-mails sent, with 43.6% from cardiac electrophysiologists, 12.8% from fellows, and 11.6% from advanced practice practitioners. Most respondents (62.3%) reported having recommended patient use of a digital device for AF detection. Those who did not had concerns about their accuracy (29.6%), clinical utility of results (22.8%), and integration into electronic health records (19.8%). Results from a 30-second single-lead electrocardiogram were sufficient for 42.7% of HCPs to recommend oral anticoagulation for patients at high risk for stroke. Respondents wanted more data comparing the accuracy of digital devices to conventional devices for AF monitoring (64.9%). A quarter (27.3%) of HCPs had no reservations recommending digital devices for AF detection, and most (53.4%) wanted guidelines from their professional societies providing guidance on their optimal use.

Conclusion

Many HCPs have already integrated digital devices into their clinical practice. However, HCPs reported facing challenges when using digital technologies for AF detection, and professional society recommendations on their use are needed.

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Extrapulmonary manifestations of COVID-19

Although COVID-19 is most well known for causing substantial respiratory pathology, it can also result in several extrapulmonary manifestations. These conditions include thrombotic complications, myocardial dysfunction and arrhythmia, acute coronary syndromes, acute kidney injury, gastrointestinal symptoms, hepatocellular injury, hyperglycemia and ketosis, neurologic illnesses, ocular symptoms, and dermatologic complications. Given that ACE2, the entry receptor for the causative coronavirus SARS-CoV-2, is expressed in multiple extrapulmonary tissues, direct viral tissue damage is a plausible mechanism of injury. In addition, endothelial damage and thromboinflammation, dysregulation of immune responses, and maladaptation of ACE2-related pathways might all contribute to these extrapulmonary manifestations of COVID-19. Here we review the extrapulmonary organ-specific pathophysiology, presentations and management considerations for patients with COVID-19 to aid clinicians and scientists in recognizing and monitoring the spectrum of manifestations, and in developing research priorities and therapeutic strategies for all organ systems involved.

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Restructuring Structural Heart Disease Practice During the COVID-19 Pandemic: JACC Review Topic of the Week

Patients with structural heart disease are at increased risk of adverse outcomes from the coronavirus disease-2019 (COVID-19) due to advanced age and comorbidity. In the midst of a global pandemic of a novel infectious disease, reality-based considerations comprise an important starting point for formulating clinical management pathways. The aims of these “crisis-driven” recommendations are: 1) to ensure appropriate and timely treatment of structural heart disease patients; 2) to minimize the risk of COVID-19 exposure to patients and health care workers; and 3) to limit resource utilization under conditions of constraint. Although the degree of disruption to usual practice will vary across the United States and elsewhere, we hope that early experiences from a heart team operating in the current global epicenter of COVID-19 may prove useful for others adapting their practice in advance of local surges of COVID-19.

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Derived telemetry-based electrocardiograms in the intensive care unit: insights from a COVID-19 epicenter

Introduction: Severely ill inpatients with SARS-CoV-2 infection, Coronavirus Disease 2019 (COVID-19) require close electrocardiographic (ECG) monitoring due to frequent cardiac involvement of the disease and cardiovascular side effects of therapies. This study aimed to compare ECG parameters measured from conventional 12-lead ECGs to those from a telemetry-generated 7-lead or single lead ECG to determine if the latter may be an alternative for screening and monitoring patients, particularly during a pandemic. Methods and Results: We identified 33 patients with respiratory failure due to COVID-19 undergoing telemetry monitoring in the intensive care unit. Each received a 12-lead ECG utilizing standard lead placement. A concurrent 7-lead ECG and single lead (lead II) tracing were obtained using the central telemetry system. Each ECG was interpreted and intervals manually measured by 2 cardiologists with disagreements adjudicated by a third. Compared to the 12-lead ECG measurement, the 7-lead ECG underestimated the corrected QT by on average 13.45±32.05 msec, and the single lead ECG underestimated corrected QT by 19.62±33.19 msec (Bazett, p < 0.05). Bland Altman analysis also demonstrated evidence of a positive bias, suggesting that the telemetry-derived tracings underestimated the QT interval. The presence of T wave abnormalities and ST segment changes were overestimated by the telemetry-derived tracings as compared to standard ECGs. Conclusion: Though telemetry-derived ECGs may be useful in screening patients for significant ECG abnormalities, they likely do not represent a reliable replacement of the standard 12-lead ECG in the routine diagnosis and management of critically ill patients.

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Year in Review in Cardiac Electrophysiology

In the past year, there have been numerous advances in our understanding of arrhythmia mechanisms, diagnosis, and new therapies. We have seen advances in basic cardiac electrophysiology with data suggesting that secretoneurin may be a biomarker for patients at risk of ventricular arrhythmias, and we have learned of the potential role of an NPR-C (natriuretic peptide receptor-C) in atrial fibrosis and the role of an atrial specific 2-pore potassium channel TASK-1 as a therapeutic target for atrial fibrillation. We have seen studies demonstrating the role of sensory neurons in sleep apnea–related atrial fibrillation and the association between bariatric surgery and atrial fibrillation ablation outcomes. Artificial intelligence applied to electrocardiography has yielded estimates of age, sex, and overall health. We have seen new tools for collection of patient-centered outcomes following catheter ablation. There have been significant advances in the ability to identify ventricular tachycardia termination sites through high-density mapping of deceleration zones. We have learned that right ventricular dysfunction may be a predictor of survival benefit after implantable cardioverter-defibrillator implantation in patients with nonischemic cardiomyopathy. We have seen further insights into the role of His bundle pacing on improving outcomes. As our understanding of cardiac laminopathies advances, we may have new tools to predict arrhythmic event rates in gene carriers. Finally, we have seen numerous advances in the treatment of arrhythmias in patients with congenital heart disease.

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Cardiac arrhythmias in COVID-19 infection

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), the virus that causes COVID-19, has affected >1 million people worldwide.1 As of this writing, >60 000 people have died as a result of this virus in the United States alone,2 and New York City has over 167 000 confirmed coronavirus disease 2019 (COVID-19) cases, the highest number of any city in the United States. New York City is now considered a COVID-19 epicenter. While this disease predominantly affects the lungs, often leading to pneumonia and acute respiratory distress syndrome, adverse effects on the heart have also been described.3 Electrophysiological issues are increasingly recognized as a disease manifestation, with one study reporting arrhythmias in 44% of individuals with severe illness.4 Sudden cardiac death has also been described anecdotally.5 However, the type and severity of arrhythmias associated with COVID-19 have not been described. In this article, we present 4 cases that highlight the spectrum of arrhythmias observed in patients with COVID-19 infection. New York-Presbyterian/Columbia University Irving Medical Center is located in the New York City COVID-19 epicenter and herein, we describe the clinical presentations we have seen and discuss decision-making regarding therapeutic options, acknowledging difficulties pertaining to resource conservation and healthcare worker safety.

This study was approved by the Columbia University Institutional Review Board, and procedures followed were in accordance with institutional guidelines. Due to the nature of the study, written informed consent was not required. The authors declare that all supporting data are available within the article.

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Performance of electrophysiology procedures at an academic medical center amidst the 2020 coronavirus (COVID‐19) pandemic

A global coronavirus (COVID‐19) pandemic occurred at the start of 2020 and is already responsible for more than 74 000 deaths worldwide, just over 100 years after the influenza pandemic of 1918. At the center of the crisis is the highly infectious and deadly SARS‐CoV‐2, which has altered everything from individual daily lives to the global economy and our collective consciousness. Aside from the pulmonary manifestations of disease, there are likely to be several electrophysiologic (EP) sequelae of COVID‐19 infection and its treatment, due to consequences of myocarditis and the use of QT‐prolonging drugs. Most crucially, the surge in COVID‐19 positive patients that have already overwhelmed the New York City hospital system requires conservation of hospital resources including personal protective equipment (PPE), reassignment of personnel, and reorganization of institutions, including the EP laboratory. In this proposal, we detail the specific protocol changes that our EP department has adopted during the COVID‐19 pandemic, including performance of only urgent/emergent procedures, after hours/7‐day per week laboratory operation, single attending‐only cases to preserve PPE, appropriate use of PPE, telemedicine and video chat follow‐up appointments, and daily conferences to collectively manage the clinical and ethical dilemmas to come. We discuss also discuss how we perform EP procedures on presumed COVID positive and COVID tested positive patients to highlight issues that others in the EP community may soon face in their own institution as the virus continues to spread nationally and internationally.

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Systems and methods for mechanical mapping of cardiac rhythm

(63) Continuation of application No. 14/682.980, filed on locations over the series of images. The periodicity corre-Apr. 9, 2015, now Pat. No. 10517.564, which is a sponds to an electromechanical signal of the heart in the continuation-in-part of application No. PCT/US13/region corresponding to the measured one or more pixel 64377, filed on Oct. 10, 2013. locations.

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Guidance for Cardiac Electrophysiology During the COVID-19 Pandemic from the Heart Rhythm Society COVID-19

Task Force; Electrophysiology Section of the American College of Cardiology; and the Electrocardiography and Arrhythmias Committee of the Council on Clinical Cardiology, American Heart Association

Coronavirus disease 2019 (COVID-19) is a global pandemic that is wreaking havoc on the health and economy of much of human civilization. Electrophysiologists have been impacted personally and professionally by this global catastrophe. In this joint article from representatives of the Heart Rhythm Society, the American College of Cardiology, and the American Heart Association, we identify the potential risks of exposure to patients, allied healthcare staff, industry representatives, and hospital administrators. We also describe the impact of COVID-19 on cardiac arrhythmias and methods of triage based on acuity and patient comorbidities. We provide guidance for managing invasive and noninvasive electrophysiology procedures, clinic visits, and cardiac device interrogations. In addition, we discuss resource conservation and the role of telemedicine in remote patient care along with management strategies for affected patients.

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Restructuring electrophysiology during the COVID-19 pandemic: a practical guide from a New York City hospital network

The coronavirus disease 2019 crisis is a global pandemic of a novel infectious disease with far-ranging public health implications. With regard to cardiac electrophysiology (EP) services, we discuss the “real-world” challenges and solutions that have been essential for efficient and successful (1) ramping down of standard clinical practice patterns and (2) pivoting of workflow processes to meet the demands of this pandemic. The aims of these recommendations are to outline: (1) essential practical steps to approaching procedures, as well as outpatient and inpatient care of EP patients, with relevant examples, (2) successful strategies to minimize exposure risk to patients and clinical staff while also balancing resource utilization, (3) challenges related to redeployment and restructuring of clinical and support staff, and (4) considerations regarding continued collaboration with clinical and administrative colleagues to implement these changes. While process changes will vary across practices and hospital systems, we believe that these experiences from 4 different EP sections in a large New York City hospital network currently based in the global epicenter of the coronavirus disease 2019 pandemic will prove useful for other EP practices adapting their own practices in preparation for local surges.

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Catheter ablation lesion visualization with intracardiac strain imaging in canines and humans

Catheter ablation is a common treatment for arrhythmia, but can fail if lesion lines are noncontiguous. Identification of gaps and nontransmural lesions can reduce the likelihood of treatment failure and recurrent arrhythmia. Intracardiac myocardial elastography (IME) is a strain imaging technique that provides visualization of the lesion line. Estimation of lesion size and gap resolution were evaluated in an open-chest canine model (n = 3), and clinical feasibility was investigated in patients undergoing ablation to treat typical cavotricuspid isthmus (CTI) atrial flutter (n = 5). A lesion line consisting of three lesions and two gaps was generated on the canine left ventricle via epicardial ablation. One lesion was generated in one canine right ventricle. Average lesion and gap areas were measured with high agreement (33 ± 14 and 30 ± 15 mm 2 , respectively) when compared against gross pathology (34 ± 19 and 26 ± 11 mm 2 , respectively). Gaps as small as 11 mm 2 (3.6 mm on epicardial surface) were identifiable. Absolute error and relative error in estimated lesion area were 9.3 ± 8.4 mm 2 and 31% ± 34%; error in estimated gap area was 11 ± 9.0 mm 2 and 40% ± 29%. Flutter patients were imaged throughout the procedure. Strain was shown to be capable of differentiating between baseline and after ablation completion as confirmed by conduction block. In all patients, strain decreased in the CTI after ablation (mean paired difference of -17% ± 11%, p <; 0.05). IME could potentially become a useful ablation monitoring tool in health facilities.

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Guidance for cardiac electrophysiology during the COVID-19 pandemic from the Heart Rhythm Society COVID-19

Task Force; Electrophysiology Section of the American College of Cardiology; and the Electrocardiography and Arrhythmias Committee of the Council on Clinical Cardiology, American Heart Association

Coronavirus disease 2019 (COVID-19) is a global pandemic that is wreaking havoc on the health and economy of much of human civilization. Electrophysiologists have been impacted personally and professionally by this global catastrophe. In this joint article from representatives of the Heart Rhythm Society, the American College of Cardiology, and the American Heart Association, we identify the potential risks of exposure to patients, allied healthcare staff, industry representatives, and hospital administrators. We also describe the impact of COVID-19 on cardiac arrhythmias and methods of triage based on acuity and patient comorbidities. We provide guidance for managing invasive and noninvasive electrophysiology procedures, clinic visits, and cardiac device interrogations. In addition, we discuss resource conservation and the role of telemedicine in remote patient care along with management strategies for affected patients.

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Noninvasive localization of cardiac arrhythmias using electromechanical wave imaging

Cardiac arrhythmias are a major cause of morbidity and mortality worldwide. The 12-lead electrocardiogram (ECG) is the current noninvasive clinical tool used to diagnose and localize cardiac arrhythmias. However, it has limited accuracy and is subject to operator bias. Here, we present electromechanical wave imaging (EWI), a high–frame rate ultrasound technique that can noninvasively map with high accuracy the electromechanical activation of atrial and ventricular arrhythmias in adult patients. This study evaluates the accuracy of EWI for localization of various arrhythmias in all four chambers of the heart before catheter ablation. Fifty-five patients with an accessory pathway (AP) with Wolff-Parkinson-White (WPW) syndrome, premature ventricular complexes (PVCs), atrial tachycardia (AT), or atrial flutter (AFL) underwent transthoracic EWI and 12-lead ECG. Three-dimensional (3D) rendered EWI isochrones and 12-lead ECG predictions by six electrophysiologists were applied to a standardized segmented cardiac model and subsequently compared to the region of successful ablation on 3D electroanatomical maps generated by invasive catheter mapping. There was significant interobserver variability among 12-lead ECG reads by expert electrophysiologists. EWI correctly predicted 96% of arrhythmia locations as compared with 71% for 12-lead ECG analyses [unadjusted for arrhythmia type: odds ratio (OR), 11.8; 95% confidence interval (CI), 2.2 to 63.2; P = 0.004; adjusted for arrhythmia type: OR, 12.1; 95% CI, 2.3 to 63.2; P = 0.003]. This double-blinded clinical study demonstrates that EWI can localize atrial and ventricular arrhythmias including WPW, PVC, AT, and AFL. EWI when used with ECG may allow for improved treatment for patients with arrhythmias.

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