Vigorous Exercise in Patients With Congenital Long-QT Syndrome: Results of the Prospective, Observational, Multinational LIVE-LQTS Study.

BACKGROUND: Whether vigorous exercise increases risk of ventricular arrhythmias for individuals diagnosed and treated for congenital long-QT syndrome (LQTS) remains unknown. METHODS: The National Institutes of Health-funded LIVE-LQTS study (Lifestyle and Exercise in Genetic Cardiovascular Conditions) prospectively enrolled individuals 8 to 60 years of age with phenotypic or genotypic LQTS from 37 sites in 5 countries from May 2015 to February 2019. Participants (or parents) answered physical activity and clinical events surveys every 6 months for 3 years with follow-up completed in February 2022. Vigorous exercise was defined as ≥6 metabolic equivalents for >60 hours per year. A blinded Clinical Events Committee adjudicated the composite end point of sudden death, sudden cardiac arrest, ventricular arrhythmia treated by an implantable cardioverter defibrillator, and likely arrhythmic syncope. A National Death Index search ascertained vital status for those with incomplete follow-up. A noninferiority hypothesis (boundary of 1.5) between vigorous exercisers and others was tested with multivariable Cox regression analysis. RESULTS: Among the 1413 participants (13% <18 years of age, 35% 18-25 years of age, 67% female, 25% with implantable cardioverter defibrillators, 90% genotype positive, and 49% with LQT1), 91% were treated with beta-blockers, left cardiac sympathetic denervation, or implantable cardioverter defibrillator; 52% participated in vigorous exercise (55% competitively). Thirty-seven individuals experienced the composite end point (including one sudden cardiac arrest and one sudden death in the nonvigorous group, one sudden cardiac arrest in the vigorous group) with overall event rates at 3 years of 2.6% in the vigorous and 2.7% in the nonvigorous exercise groups. The unadjusted hazard ratio for experience of events for the vigorous group compared with the nonvigorous group was 0.97 (90% CI, 0.57-1.67), with an adjusted hazard ratio of 1.17 (90% CI, 0.67-2.04). The upper 95% one-sided confidence level extended beyond the 1.5 boundary. Neither vigorous or nonvigorous exercise was found to be superior in any group or subgroup. CONCLUSIONS: Among individuals diagnosed with phenotypic or genotypic LQTS who were risk assessed and treated in experienced centers, LQTS-associated cardiac event rates were low and similar between those exercising vigorously and those not exercising vigorously. Consistent with the low event rate, CIs are wide, and noninferiority was not demonstrated. These data further inform shared decision-making discussions between patient and physician about exercise and competitive sports participation. REGISTRATION: URL: https://www.clinicaltrials.gov; Unique identifier: NCT02549664.

Vigorous Exercise in Patients With Hypertrophic Cardiomyopathy.

Importance: Whether vigorous intensity exercise is associated with an increase in risk of ventricular arrhythmias in individuals with hypertrophic cardiomyopathy (HCM) is unknown. Objective: To determine whether engagement in vigorous exercise is associated with increased risk for ventricular arrhythmias and/or mortality in individuals with HCM. The a priori hypothesis was that participants engaging in vigorous activity were not more likely to have an arrhythmic event or die than those who reported nonvigorous activity. Design, Setting, and Participants: This was an investigator-initiated, prospective cohort study. Participants were enrolled from May 18, 2015, to April 25, 2019, with completion in February 28, 2022. Participants were categorized according to self-reported levels of physical activity: sedentary, moderate, or vigorous-intensity exercise. This was a multicenter, observational registry with recruitment at 42 high-volume HCM centers in the US and internationally; patients could also self-enroll through the central site. Individuals aged 8 to 60 years diagnosed with HCM or genotype positive without left ventricular hypertrophy (phenotype negative) without conditions precluding exercise were enrolled. Exposures: Amount and intensity of physical activity. Main Outcomes and Measures: The primary prespecified composite end point included death, resuscitated sudden cardiac arrest, arrhythmic syncope, and appropriate shock from an implantable cardioverter defibrillator. All outcome events were adjudicated by an events committee blinded to the patient's exercise category. Results: Among the 1660 total participants (mean [SD] age, 39 [15] years; 996 male [60%]), 252 (15%) were classified as sedentary, and 709 (43%) participated in moderate exercise. Among the 699 individuals (42%) who participated in vigorous-intensity exercise, 259 (37%) participated competitively. A total of 77 individuals (4.6%) reached the composite end point. These individuals included 44 (4.6%) of those classified as nonvigorous and 33 (4.7%) of those classified as vigorous, with corresponding rates of 15.3 and 15.9 per 1000 person-years, respectively. In multivariate Cox regression analysis of the primary composite end point, individuals engaging in vigorous exercise did not experience a higher rate of events compared with the nonvigorous group with an adjusted hazard ratio of 1.01. The upper 95% 1-sided confidence level was 1.48, which was below the prespecified boundary of 1.5 for noninferiority. Conclusions and Relevance: Results of this cohort study suggest that among individuals with HCM or those who are genotype positive/phenotype negative and are treated in experienced centers, those exercising vigorously did not experience a higher rate of death or life-threatening arrhythmias than those exercising moderately or those who were sedentary. These data may inform discussion between the patient and their expert clinician around exercise participation.

Atrial fibrillation ablation strategies and technologies: past, present, and future.

Catheter ablation is an established treatment option for atrial fibrillation (AF), and pulmonary vein isolation (PVI) has become the gold standard in AF ablation. AF recurrence after PVI remains an important clinical problem. Recovery of conduction from the pulmonary veins (PVs) is considered the dominant mechanism for AF recurrence in paroxysmal AF. However, the underlying mechanism of AF recurrence after PVI is more complex in patients with persistent and longstanding persistent AF. Different ablation technologies and energy sources have been developed aimed at improving lesion quality and durability with an acceptable safety profile. Novel technologies are under evaluation which have a great potential to produce permanent PVI after a single ablation procedure. However, clinical value of these novel devices needs to be tested in adequately powered randomized controlled trials. In this article, we review the history of catheter ablation for AF and discuss the present and future ablation technologies.

Association of the US Department of Justice Investigation of Implantable Cardioverter-Defibrillators and Devices Not Meeting the Medicare National Coverage Determination, 2007-2015.

Importance: The US Department of Justice (DOJ) conducted an investigation into implantable cardioverter-defibrillators (ICDs) not meeting the Centers for Medicare & Medicaid Services National Coverage Determination (NCD) criteria. Objective: To examine changes in the proportion of initial primary prevention ICDs that did not meet NCD criteria following the announcement of the DOJ investigation at hospitals that reached settlements (settlement hospitals) and those that did not (nonsettlement hospitals). Design, Setting, and Participants: Multicenter, longitudinal, serial cross-sectional analysis of 300 151 initial primary prevention ICDs among Medicare beneficiaries from January 1, 2007, through December 31, 2015, at 1809 US hospitals in the National Cardiovascular Data Registry (NCDR) ICD Registry, of which 452 hospitals (with 99 591 primary prevention ICDs) reached settlements with the DOJ. Exposures: The DOJ investigation announcement in 2010. Main Outcomes and Measures: Proportion of initial primary prevention ICDs not meeting NCD criteria. Results: In January 2007, the proportion of initial ICDs not meeting NCD criteria was 25.8% (95% CI, 24.7% to 26.8%) at settlement hospitals and 22.8% (95% CI, 22.1% to 23.5%) at nonsettlement hospitals (P < .001). Over the study period, there was a 62.7% (95% CI, 59.2% to 66.1%) relative decrease and 16.1% (95% CI, 14.8% to 17.5%) absolute decrease in the proportion of ICDs not meeting NCD criteria at settlement hospitals compared with a 53.2% (95% CI, 50.4% to 56.0%) relative decrease and 12.1% (95% CI, 11.2% to 13.0%) absolute decrease in proportion at nonsettlement hospitals (P < .001 for both; P for interaction < .001). Trends significantly differed between hospital groups only in the period following the announcement of the DOJ investigation (January 2010-June 2011) [corrected], with larger and more rapid decreases at settlement hospitals (P for interaction = .01). Over the study period, there was a 32.8% (95% CI, 29.9% to 35.7%) relative decrease and a 1703 ICDs (95% CI, 1520 to 1886) absolute decrease in the volume of primary prevention ICDs implanted at settlement hospitals compared with a 17.4% (95% CI, 14.8% to 20.0%) relative decrease and a 1495 ICDs (95% CI, 1249 to 1741) absolute decrease in volume at nonsettlement hospitals (P < .001 for both; P for interaction < .001), with more modest decreases or slight increases in secondary prevention ICD volume. These patterns were similar when examining ICD utilization among non-Medicare beneficiaries. Conclusions and Relevance: From 2007 through 2015, the volume of primary prevention implantable cardioverter-defibrillators and the proportion of devices not meeting the Centers for Medicare & Medicaid Services National Coverage Determination criteria decreased at all hospitals with substantially larger decreases at hospitals that reached settlements in the US Department of Justice investigation. These patterns extended to implantable cardioverter-defibrillators placed in non-Medicare beneficiaries, which were not the focus of the US Department of Justice investigation.

Updated Recommendations for Athletes with Heart Disease.

Professional society recommendations to decrease sudden cardiac death in athletes, including eligibility requirements with disqualification for athletes with diagnosed disease as well as preparticipation screening and emergency preparedness, were updated in 2015. The update includes new sections on aortic disease, channelopathies, and sickle cell trait, as well as a change in format from the previous binary yes/no format to the more nuanced and contemporary "class and level of evidence" format. Eighty-four of the 246 recommendations now carry Class II designation-"reasonable," or "may be considered." New language in the document emphasizes counseling as part of the decision process. New data on athletes with implantable cardioverter-defibrillators, and on those with long QT syndrome, have led to a change from blanket restriction of competitive sports participation to a Class IIB "may be considered" recommendation.

Clinical neurocardiology defining the value of neuroscience-based cardiovascular therapeutics.

The autonomic nervous system regulates all aspects of normal cardiac function, and is recognized to play a critical role in the pathophysiology of many cardiovascular diseases. As such, the value of neuroscience-based cardiovascular therapeutics is increasingly evident. This White Paper reviews the current state of understanding of human cardiac neuroanatomy, neurophysiology, pathophysiology in specific disease conditions, autonomic testing, risk stratification, and neuromodulatory strategies to mitigate the progression of cardiovascular diseases.

Determining the Feasibility of Spinal Cord Neuromodulation for the Treatment of Chronic Systolic Heart Failure: The DEFEAT-HF Study.

OBJECTIVES: The primary objective of the study was a change in left ventricular end-systolic volume index (LVESVi) from baseline to 6 months of spinal cord stimulation (SCS) therapy in the treatment arm compared to the control arm as measured by echocardiography. Secondary objectives were changes in peak oxygen uptake and N-terminal pro-B-type natriuretic peptide (NT-proBNP) between the treatment arm and control arm from baseline through 6 months. BACKGROUND: Abnormal neurohormonal activation is often responsible for progression of heart failure (HF). Treatment has often included drug therapy to modulate the neurohormonal axis. The purpose of the DEFEAT-HF (Determining the Feasibility of Spinal Cord Neuromodulation for the Treatment of Chronic Heart Failure) clinical study was to evaluate whether direct modulation of the nervous system through SCS improved HF metrics, including heart size, biomarkers, functional capacity, and symptoms. METHODS: The DEFEAT-HF study was a prospective, multicenter randomized (3:2), parallel, single-blind, controlled study to investigate whether SCS was a feasible therapy for the treatment of systolic HF for patients with New York Heart Association functional class III HF, left ventricular ejection fraction (LVEF) ≤35%, QRS duration <120 ms, and left ventricular end-diastolic dimension ≥55 mm. The primary objective of the DEFEAT-HF study was to evaluate the reduction in LVESVi after 6 months of SCS therapy in the treatment arm compared to the control arm. RESULTS: In total, 81 patients were enrolled, with 66 successfully randomized and implanted with the SCS device system. Seventy-six percent (50 of 66) had an implantable cardioverter-defibrillator at the baseline visit. Among randomized patients, the mean age was 61 years, 79% were male, mean LVEF was 27%, and mean QRS duration was 105 ms. The change in LVESVi over 6 months was not significantly different between randomization arms (SCS OFF: -2.2 [95% confidence interval: -9.1 to 4.6] vs. SCS ON: 2.1 [95% confidence interval: -2.7 to 6.9]; p = 0.30). Analyses of secondary endpoints for the study were also not significantly different. CONCLUSIONS: The present study does not provide evidence to support a meaningful change in clinical outcomes for HF patients receiving SCS. (Determining the Feasibility of Spinal Cord Neuromodulation for the Treatment of Chronic Heart Failure [DEFEAT-HF]; NCT01112579).