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Background Sudden cardiac death (SCD) is the leading cause of duty‐related death among firefighters. Understanding postmortem cardiovascular abnormalities associated with SCD is critical to guiding fire service cardiovascular disease screening and prevention programs. Methods This study included US firefighters who had a duty‐related death over a 16‐year period (1999–2014) with available postmortem reports (autopsy/medical examiner reports). Cases were systematically reviewed to identify cases of SCD. For each SCD case, the primary etiology of SCD was adjudicated by experts in sports cardiology and cardiovascular pathology. Results Postmortem evaluations were available for 794 of 2100 (37.8%) on‐duty firefighter deaths over the study period (average age, 44±13 years; age range, 17–82 years; 4.0% women). A total of 312 of 794 (39.3%) firefighter deaths were adjudicated as SCD. A total of 255 of 312 (81.8%) SCD events were attributable to coronary artery disease/ischemic heart disease or hypertensive heart disease, which both are associated with traditional cardiovascular risk factors. The leading etiology of SCD among young firefighters (aged <40 years) was also coronary artery disease/ischemic heart disease (24/50 [48.0%]). Of firefighters who had an exertional SCD event thought to be secondary to coronary artery disease (n=97), a total of 62 of 91 (68.1%) had severe fixed coronary stenosis, while 29 of 91 (31.9%) demonstrated acute plaque rupture/thrombosis. Conclusions More than 80% of on‐duty SCD events among US firefighters are due to coronary artery disease and hypertensive heart disease that may be prevented by early disease identification and risk factor modification. Future studies should assess the efficacy of more rigorous firefighter cardiovascular disease screening and management practices.

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 the Long QT Syndrome) prospectively enrolled individuals 8 to 60 years of age with phenotypic and/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, 49% with LQT1, 91% were treated with beta-blockers, left cardiac sympathetic denervation, and/or implantable cardioverter defibrillator), 52% participated in vigorous exercise (55% of these 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 and/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.

Background: The incidence and causes of sudden cardiac death (SCD) among young competitive athletes impact prevention strategies yet remain incompletely understood. Methods: National Collegiate Athletic Association (NCAA) athlete deaths from 7/1/2002-6/30/2022 were identified through 4 independent databases/search strategies. Autopsy reports and medical history were reviewed by an expert panel to adjudicate causes of SCD. Poisson regression was used to calculate incidence rate ratios (IRR) for 5-year intervals over the 20-year study. Results: A total of 143 SCD cases were identified among 1102 athlete deaths and 9,106,516 athlete-years (AYs). The incidence of SCD among NCAA athletes was 1:63,682 AYs [95% CI 1:54,065, 1:75,010]. Incidence was higher in males compared to females (1:43,348 vs. 1:164,504 AYs) and Black compared to White athletes (1:27,217 vs. 1:74,581 AYs). The highest incidence of SCD was among Division 1 male basketball players (1:8,188; White 1:5,848; Black 1:7,696 AYs). The incidence rate for SCD decreased over the study period (5-year IRR 0.71 [95% CI 0.61,0.82]), whereas the rate of non-cardiovascular deaths remained stable (5-year IRR 0.98 [95% CI 0.94,1.04]; Figure 1A ). Autopsy-negative sudden unexplained death (AN-SUD, 19.5%) was the most common post-mortem exam finding, followed by idiopathic left ventricular hypertrophy/possible cardiomyopathy (CM, 16.9%) and hypertrophic CM (12.7%) in cases with enough information for adjudication (118/143, Figure 1B ). There were 8 cases of myocarditis, with none attributed to COVID-19 infection. SCD events occurred most commonly during exertion among athletes with coronary artery anomalies (100%) and arrhythmogenic CM (83%), whereas AN-SUD and hypertrophic CM had a higher proportion of non-exertional SCD (44% and 40%, respectively). Conclusions: The incidence of SCD in college athletes has decreased. Male sex, Black race, and basketball are associated with a higher incidence of SCD.

BACKGROUND: Understanding the incidence, causes, and trends of sudden cardiac death (SCD) among young competitive athletes is critical to inform preventive policies. METHODS: This study included National Collegiate Athletic Association athlete deaths during a 20-year time frame (July 1, 2002, through June 30, 2022). Athlete deaths were identified through 4 separate independent databases and search strategies (National Collegiate Athletic Association resolutions list, Parent Heart Watch database and media reports, National Center for Catastrophic Sports Injury Research database, and insurance claims). Autopsy reports and medical history were reviewed by an expert panel to adjudicate causes of SCD. RESULTS: A total of 143 SCD cases in National Collegiate Athletic Association athletes were identified from 1102 total deaths. The National Collegiate Athletic Association resolutions list identified 117 of 143 (82%), the Parent Heart Watch database or media reports identified 89 of 143 (62%), the National Center for Catastrophic Sports Injury Research database identified 63 of 143 (44%), and insurance claims identified 27 of 143 (19%) SCD cases. The overall incidence of SCD was 1:63 682 athlete-years (95% CI, 1:54 065–1:75 010). Incidence was higher in male athletes than in female athletes (1:43 348 [95% CI, 1:36 228–1:51 867] versus 1:164 504 [95% CI, 1:110 552–1:244 787] athlete-years, respectively) and Black athletes compared with White athletes (1:26 704 [1:20 417–1:34 925] versus 1:74 581 [1:60 247–1:92 326] athlete-years, respectively). The highest incidence of SCD was among Division I male basketball players (1:8188 [White, 1:5848; Black, 1:7696 athlete-years]). The incidence rate for SCD decreased over the study period (5-year incidence rate ratio, 0.71 [95% CI, 0.61–0.82]), whereas the rate of noncardiovascular deaths remained stable (5-year incidence rate ratio, 0.98 [95% CI, 0.94–1.04]). Autopsy-negative sudden unexplained death (19.5%) was the most common postmortem examination finding, followed by idiopathic left ventricular hypertrophy or possible cardiomyopathy (16.9%) and hypertrophic cardiomyopathy (12.7%), in cases with enough information for adjudication (118 of 143). Eight cases of death were attributable to myocarditis over the study period (1 case from January 1, 2020, through June 30, 2022), with none attributed to COVID-19 infection. SCD events were exertional in 50% of cases. Exertional SCD was more common among those with coronary artery anomalies (100%) and arrhythmogenic cardiomyopathy (83%). CONCLUSIONS: The incidence of SCD in college athletes has decreased. Male sex, Black race, and basketball are associated with a higher incidence of SCD.

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.

Introduction: Safety of vigorous exercise for individuals with appropriately-treated HCM remains debated. Physical activity practices in this population have not been described. The objective of this report is to describe physical activity pattern in HCM patients. Long term follow up which is ongoing will determine safety of vigorous exercise. Methods: The NIH-funded LIVE-HCM study prospectively enrolled individuals age 8-60 years with clinically overt HCM or patients with a positive genetic test for sarcomeric HCM. Participants (or parents, for children) answered surveys describing activity patterns. Vigorous exercise was defined as > 6 METS for > 60 hours per year. Clinical and demographic data were derived from medical record review. Results: Among 1798 participants, 745 (41%) reported exercising vigorously, including 296 competitive athletes, with 59 at high-school or college varsity level, 770 (43%) were exercising at moderate, and 283 (16%) at low levels. Of those working, 6% described jobs more active than walking, including 16 in protective services, and 11 in sports/coaching. Clinical/demographic data including imaging characteristics and treatments, are shown in Table, and were mostly similar amongst the exercise-groups. Conclusions: Many patients with HCM are engaged in vigorous exercise including competitive athletics. Prospective follow-up of this cohort is ongoing. Comparison of arrhythmic outcomes outcomes in vigorous exercisers vs moderate/low level exercisers will help determine the safety of exercise in HCM patients.