Extended Ambulatory ECG Monitoring Enhances Identification of Higher-Risk Ventricular Tachyarrhythmias in Patients with Hypertrophic Cardiomyopathy.

BACKGROUND: In hypertrophic cardiomyopathy (HCM), 48-hour ambulatory monitoring has been standard practice to detect nonsustained ventricular tachycardia (NSVT), a sudden death risk marker. Extended wear ambulatory ECG devices have more recently utilized for monitoring HCM patients. OBJECTIVE: Evaluate NSVT burden identified with continuous ambulatory monitoring for up to 2 weeks compared to initial 48 hours. METHODS: 236 consecutive HCM patients (49 ± 12 years) underwent 14-day continuous ambulatory monitoring (Zio XT, iRhythm Technologies); diagnostic yield of NSVT compared for initial 48 hours vs. extended for 14 days. RESULTS: Of 236 patients, 114 (48%) had ≥1 runs of NSVT (median 2) over 14 days. Median length of NSVT was 7 beats (range: 3 to 67) at rates of 120 to 240 bpm (median, 167 bpm). In 42 of the 114 patients (37%), initial NSVT occurred ≤ 48 hours and in 72 (63%) only during the extended monitoring period (3 to 14 days). Diagnostic yield for detecting NSVT over 14 days was 2.7-fold greater than ≤ 48 hours (p<0.001). NSVT judged at higher risk (≥8 beats, >200 bpm, ≥2 runs in consecutive 2-day period) was identified more frequently during extended monitoring, diagnostic yield 3.0-fold greater than ≤ 48 hours (p<0.001). CONCLUSION: In HCM, NSVT episodes are frequent, however, in most patients, both NSVT and higher risk NSVT were not detected during initial 48-hours and confined solely to extended monitoring period. These data support additional clinical studies to evaluate the significance of NSVT on extended monitoring on sudden death risk in HCM.

Nationwide Trends in Hospitalizations for Atrial Fibrillation and Flutter in the United States before and during the Outbreak of the COVID-19 Pandemic.

Background/Objectives: Atrial fibrillation (AF) and flutter (AFL) are the most common cardiac arrhythmias worldwide. Cardiovascular complications are a common manifestation of acute and post-acute COVID-19 infection. We aimed to analyze the nationwide trends in clinical characteristics and outcomes of patients hospitalized for AF/AFL before and during the COVID-19 outbreak in the U.S. Methods: This study is a retrospective analysis of patients, aged 18 and older, hospitalized for AF/AFL in the U.S. between 2016 and 2020. We drew data from the National Inpatient Sample (NIS) database. Baseline sociodemographic and clinical data, as well as outcomes including stroke, acute coronary syndrome (ACS), and mortality, were analyzed. Multivariable analysis was performed to identify independent associations between the different clinical and demographic characteristics and the composite endpoint of Mortality/ACS/Stroke. Results: An estimated total of 2,163,699 hospitalizations for AF/AFL were identified. The hospitalization volume between 2016 and 2019 was stable, averaging 465,176 a year, followed by a significant drop to 302,995 in 2020. Patients' median age was 72 years (IQR 62-80), 50.9% were male, and 81.5% were white. The composite endpoint steadily increased from 6.5% in 2016 to 11.8% in 2020 (Ptrend < 0.001). In a multivariable regression analysis, age > 75 (OR: 1.35; 95% CI 1.304-1.399, p < 0.001), ischemic heart disease (OR: 1.466; 95% CI: 1.451-1.481; p < 0.001), and chronic kidney disease (OR: 1.635; 95% CI: 1.616-1.653; p < 0.001) were associated with the composite endpoint. COVID-19 was associated with the composite endpoint outcome in the year 2020 (OR: 1.147; 95% CI: 1.037-1.265; p = 0.007). Conclusions: Hospitalization for AF/AFL dropped significantly during the first year of the COVID-19 pandemic outbreak, possibly due to patients' avoidance of hospital visits. The composite endpoint of Mortality/ACS/Stroke uptrended significantly during the study period. COVID-19 was shown to be independently associated with the adverse composite outcome Mortality/ACS/Stroke.

Identification of high-risk imaging features in hypertrophic cardiomyopathy using electrocardiography: A deep-learning approach.

BACKGROUND: Patients with hypertrophic cardiomyopathy (HCM) are at risk of sudden death, and individuals with ≥1 major risk markers are considered for primary prevention implantable cardioverter-defibrillators. Guidelines recommend cardiac magnetic resonance (CMR) imaging to identify high-risk imaging features. However, CMR imaging is resource intensive and is not widely accessible worldwide. OBJECTIVE: The purpose of this study was to develop electrocardiogram (ECG) deep-learning (DL) models for the identification of patients with HCM and high-risk imaging features. METHODS: Patients with HCM evaluated at Tufts Medical Center (N = 1930; Boston, MA) were used to develop ECG-DL models for the prediction of high-risk imaging features: systolic dysfunction, massive hypertrophy (≥30 mm), apical aneurysm, and extensive late gadolinium enhancement. ECG-DL models were externally validated in a cohort of patients with HCM from the Amrita Hospital HCM Center (N = 233; Kochi, India). RESULTS: ECG-DL models reliably identified high-risk features (systolic dysfunction, massive hypertrophy, apical aneurysm, and extensive late gadolinium enhancement) during holdout testing (c-statistic 0.72, 0.83, 0.93, and 0.76) and external validation (c-statistic 0.71, 0.76, 0.91, and 0.68). A hypothetical screening strategy using echocardiography combined with ECG-DL-guided selective CMR use demonstrated a sensitivity of 97% for identifying patients with high-risk features while reducing the number of recommended CMRs by 61%. The negative predictive value with this screening strategy for the absence of high-risk features in patients without ECG-DL recommendation for CMR was 99.5%. CONCLUSION: In HCM, novel ECG-DL models reliably identified patients with high-risk imaging features while offering the potential to reduce CMR testing requirements in underresourced areas.

Single- Versus Dual-Chamber Implantable Cardioverter-Defibrillator for Primary Prevention of Sudden Cardiac Death in the United States.

Background Routine addition of an atrial lead during an implantable cardioverter-defibrillator (ICD) implantation for primary prevention of sudden cardiac death, in patients without pacing indications, was not shown beneficial in contemporary studies. We aimed to investigate the use and safety of single- versus dual-chamber ICD implantations in these patients. Methods and Results Using the National Inpatient Sample database, we identified patients with no pacing indications who underwent primary-prevention ICD implantation in the United States between 2015 and 2019. Sociodemographic and clinical characteristics, as well as in-hospital complications, were analyzed. Multivariable logistic regression was used to identify predictors of in-hospital complications. An estimated total of 15 940 patients, underwent ICD implantation for primary prevention of sudden cardiac death during the study period, 8860 (55.6%) received a dual-chamber ICD. The mean age was 64 years, and 66% were men. In-hospital complication rates in the dual-chamber ICD and single-chamber ICD group were 12.8% and 10.7%, respectively (P<0.001), driven by increased rates of pneumothorax/hemothorax (4.6% versus 3.4%; P<0.001) and lead dislodgement (3.6% versus 2.3%; P<0.001) in the dual-chamber ICD group. Multivariable analyses confirmed atrial lead addition as an independent predictor for "any complications" (odds ratio [OR], 1.1 [95% CI, 1.0-1.2]), for pneumo/hemothorax (odds ratio, 1.1 [95% CI, 1.0-1.4]), and for lead dislodgement (odds ratio, 1.3 [95% CI, 1.1-1.6]). Conclusions Despite lack of evidence for clinical benefit, dual-chamber ICDs are implanted for primary prevention of sudden cardiac death in a majority of patients who do not have pacing indication. This practice is associated with increased risk of periprocedural complications. Avoidance of routine implantation of atrial leads will likely improve safety outcomes.

Bayés syndrome secondary to atrial lipoma.

This case describes a 74-year-old male who presented with rapid atrial flutter in association with large atrial lipoma along the interatrial septum. Conversion to sinus rhythm revealed the electrocardiographic criteria for advanced interatrial block. Interatrial block results from disruption of conduction through Bachmann's bundle, most commonly due to progressive atrial fibrosis. Bayés syndrome is recognized as the association of atrial arrhythmias with underlying interatrial block. This case supports the concept that localized disruption of atrial conduction via Bachmann's bundle from an atrial lipoma can produce the electrophysiologic substrate for atrial arrhythmias and the Bayés syndrome.

Cats Have Nine Lives but This Hypertrophic Cardiomyopathy Patient Has Had Ten (So Far).

In this report, we describe the unusual but highly informative clinical course of a high-risk hypertrophic cardiomyopathy patient who has to date experienced 10 appropriate primary prevention implantable cardioverter-defibrillator therapies terminating ventricular fibrillation over a 19-year period. Most patients in the Tufts HCM cohort with primary prevention experienced either 1 such therapy (66%) or 1 to 3 interventions (91%) over time. These observations underscore the opportunity for sudden death prevention in hypertrophic cardiomyopathy attributable to efficacy of the implanted defibrillator and the reliability of the American Heart Association/American College of Cardiology individual risk marker strategy.

Impact of comorbidities on atrial fibrillation and sudden cardiac death in hypertrophic cardiomyopathy.

BACKGROUND: The impact of comorbid disease states on the development of atrial and ventricular arrhythmias in patients with hypertrophic cardiomyopathy (HCM) remains unresolved. OBJECTIVE: Evaluate the association of comorbidities linked to arrhythmias in other cardiovascular diseases (e.g., obesity, systemic hypertension, diabetes, obstructive sleep apnea, renal disorders, tobacco, and alcohol use) to atrial fibrillation (AF) and sudden cardiac death (SCD) events in a large cohort of HCM patients. METHODS: A total  of 2269 patients, 54 ± 15 years of age, 1392 males, were evaluated at the Tufts HCM Institute between 2004 and 2018 and followed for an average of 4 ± 3 years for new-onset clinical AF and SCD events (appropriate defibrillation for ventricular tachyarrhythmias, resuscitated cardiac arrest, or SCD). RESULTS: One or more comorbidity was present in 75% of HCM patients, including 50% with ≥2 comorbidities, most commonly obesity (body mass index [BMI] ≥ 30 kg/m2 ) in 43%. New-onset atrial fibrillation developed in 11% of our cohort (2.6%/year). On univariate analysis, obesity was associated with a 1.7-fold increased risk for AF (p = .03) with 12% of obese patients developing AF (3.3%/year) as compared to 7% of patients with BMI < 25 kg/m2 (1.6%/year; p = .006). On multivariate analysis, age and LA transverse dimension emerged as the only variables predictive of AF. Comorbidities, including obesity, were not independently associated with AF development (p > .10 for each). SCD events occurred in 3.3% of patients (0.8%/year) and neither obesity nor other comorbidities were associated with increased risk for SCD (p > .10 for each). CONCLUSIONS: In adult HCM patients comorbidities do not appear to impact AF or SCD risk. Therefore, for most patients with HCM, adverse disease related events of AF and SCD appear to be primarily driven by underlying left ventricular and atrial myopathy as opposed to comorbidities.

Exercise and Athletic Activity in Atrial Fibrillation.

Moderate-intensity exercise improves cardiovascular outcomes. However, mounting clinical evidence demonstrates that long-term, high-intensity endurance training predisposes male and veteran athletes to an increased risk of atrial fibrillation (AF), a risk that is not observed across both genders. Although increased mortality associated with AF in the general population is not shared by athletes, clinically significant morbidities exist (eg, reduced exercise capacity, athletic performance, and quality of life). Additional research is needed to fill current gaps in knowledge pertaining to the natural history, pathophysiologic mechanisms, and management strategies of AF in the athlete.

The Convergent Procedure: A Unique Multidisciplinary Hybrid Treatment of Atrial Fibrillation.

The convergent procedure is a hybrid ablation treatment for atrial fibrillation. It is increasingly considered as a management option for patients with persistent and long-standing atrial fibrillation. It consists of surgical ablation of the posterior left atrium through a minimally invasive closed-chest approach followed by endocardial catheter ablation. It is increasingly performed with concurrent epicardial occlusion of the left atrial appendage with a video-assisted thoracoscopic technique to physically and electrically isolate the left atrial appendage. This article provides an overview of a multidisciplinary approach to the convergent procedure, with concurrent thoracoscopic closure of the left atrial appendage, with an emphasis on perioperative management at a single institution. It provides a literature review of procedural outcomes, current data limitations, and future considerations.

Long-Term Outcome in High-Risk Patients With Hypertrophic Cardiomyopathy After Primary Prevention Defibrillator Implants.

BACKGROUND: The implantable cardioverter-defibrillator (ICD) is effective for preventing sudden death in patients with hypertrophic cardiomyopathy. However, data on performance and complications of implanted ICDs over particularly long time periods to inform clinical practice is presently incomplete. METHODS: The study cohort comprises 217 consecutive hypertrophic cardiomyopathy patients with primary prevention ICDs implanted before 2008 and followed for ≥10 years (mean 12±4; range to 31). RESULTS: Patients were 38±17 years at implant and 45 (21%) experienced appropriate interventions terminating ventricular tachycardia/ventricular fibrillation. The majority of ICD discharges occurred ≥5 years after implant (29 patients; 64%), including ≥10 years in 16 patients (36%). Initial device therapy increased in frequency from 2.3% of patients at <1 year to 8.5% of patients at ≥10-years after implant (P=0.005). Inappropriate ICD shocks in 39 patients occurred most commonly <5 years after implant (54%) and decreased in frequency with increasing time from implant (from 9.7% of patients at <5 years to 3.8% at ≥10 years, P=0.02). Other major device complications including infection and lead fractures and dislodgement occurred in 27 patients (12%) but did not increase in frequency over follow-up after implant (P=0.47). There were no arrhythmic sudden death events among the 217 patients with ICD. CONCLUSIONS: In hypertrophic cardiomyopathy, after a primary prevention implant, ICD therapy often followed prolonged periods of device dormancy and increased progressively in frequency over time, including one-third of patients with initial therapy after 5 to 9 years, and an additional one-third of patients at ≥10 years. Frequency of inappropriate shocks decreased over follow-up, likely reflecting standard changes in device programming, while occurrence of device complications, such as lead fractures/infection, did not increase during follow-up.

Prediction and Prevention of Sudden Death in Young Patients (<20 years) With Hypertrophic Cardiomyopathy.

Highly reliable identification of adults with hypertrophic cardiomyopathy (HC) at risk for sudden death (SD) has been reported. A significant controversy remains, however, regarding the most reliable risk stratification methodology for children and adolescents with HC. The present study assesses the accuracy of SD prediction and prevention with prophylactic implantable cardioverter-defibrillators (ICDs) in young HC patients. The study group is comprised of 146 HC patients <20 years of age evaluated consecutively over 17 years with prospective risk stratification and ICD decision-making. We relied on ≥1 established individual risk markers considered major within each patient's clinical profile, based on an enhanced American College of Cardiology /American Heart Association (ACC/AHA) guidelines algorithm. Of the 60 largely asymptomatic patients implanted with primary prevention ICDs at age 15 ± 4 years, 9 (15%) experienced device therapy terminating potentially lethal ventricular tachyarrhythmias and restoring sinus rhythm at 19 ± 6 years (range 9 to 29), 5.1 ± 6.0 years after implant; 3 patients had multiple appropriate ICD discharges. The individual risk marker algorithm was associated with 100% sensitivity in predicting SD events (95%CI: 69, 100) and 63% specificity for identifying patients without events (95%CI: 54, 71). Of these patients with device therapy, massive left ventricular hypertrophy (absolute wall thickness ≥30 mm) was the most common predictor, present in 70% of patients either alone or in combination with other risk markers. Each of the 146 study patients have survived to date at 22 ± 5 years, including all 86 without ICD recommendations. In conclusion, an enhanced ACC/AHA risk stratification strategy, based on established individual risk markers, was highly reliable in prospectively predicting SD events in children and adolescents with HC, and preventing arrhythmia-based catastrophes in this susceptible high risk population.

Single Coil Implantable Cardioverter Defibrillator Leads in Patients With Hypertrophic Cardiomyopathy.

Patients with hypertrophic cardiomyopathy (HC) may require higher energies to terminate ventricular fibrillation (VF); thus, dual coil defibrillation leads are often implanted. However, single coil leads may be preferred in young patients. All patients with HCM implanted with a transvenous ICD from years 2000 to 2014 were included. Of 249 patients, 223 underwent VF testing including 150 with a dual coil lead and 73 a single coil. Patients tested with dual coil compared with single coil had lower successful VF energies (15.7 ± 6.1 joule to 20.2 ± 7.9 joule (p <0.0001)). Adequate safety margin for defibrillation was noted in 97.3% of patients. Notably, 6 (4 with single coil leads) had inadequate safety margins (defined as ≥10 joule). Three of these 6 patients required replacement of a single coil lead with a dual coil lead. The remaining 3 underwent waveform tilt alteration, higher energy ICD, or removal of the can from the shock vector. There were no clinical or implant predictors of inadequate safety margins. In follow-up of 16 ± 30 months (range 0 to 170), there were 24 arrhythmias including 13 VF, all successfully terminated. In conclusion, in HC patients undergoing ICD implantation, single coil leads can provide adequate safety margins. In conclusion, defibrillation testing should be considered in all HC patients undergoing ICD implantation, and should be performed in those undergoing implantation with a single coil lead.