Sudden Cardiac Arrest in a Young Population: Not So Unpredictable Dianne L. Atkins Originally published19 Jan 2019https://doi.org/10.1161/JAHA.118.011700Journal of the American Heart Association. 2019;8 Abstract See Article by Allan et al “A 6‐foot‐8, 260‐pound forward, Lewis collapsed in the second half of Division II Southern Indiana's road win over rival Kentucky Wesleyan on January 14, 2010. He died, they would learn later, due to a heart condition he never knew he had.”1 Highly publicized events such as this promote a common perception that young people who die suddenly tend to be athletes with undiagnosed heart disease. Prior studies have added to this misperception with data suggesting that most victims die of hypertrophic cardiomyopathy. Because study populations often are adolescent athletes, exercise was found to be a major trigger.2 Two recent population‐based studies of all cardiovascular‐related sudden cardiac arrest (SCA) in people 0 to 35 years of age concluded that most events occur during nonathletic activities, and hypertrophic cardiomyopathy was not the most common cause of arrest.3 A surprising finding was the presence of cardiovascular risk factors (obesity, smoking, hyperlipidemia) in a high percentage of the victims.4 In this issue of the Journal of the American Heart Association(JAHA), Allan et al have extended these studies with complete evaluation of all pertinent data from victims aged 2 to 45 years in Toronto (Ontario, Canada), the largest metropolitan area of these 3 studies.3 The data were collected from the Rescu Epistry, a database developed from the Resuscitation Outcomes Consortium Cardiac Epistry and Strategies for Post Arrest Resuscitation Care. Rescu Epistry links emergency medical systems (EMS) data with hospital data and captures all patients for whom a 911 call was made in a metropolitan area of 6.8 million people. The study population consisted of all out‐of‐hospital cardiac arrests, aged 2 to 45 years, that were presumed cardiac cause as defined by the Utstein criteria,6 as well as drownings and motor vehicle collisions that could have been caused by an SCA. The investigators undertook a comprehensive review of each case, which included EMS and in‐hospital data, as well as police reports, death certificates, coroner investigation statements, and autopsies, some of which included toxicology and molecular autopsies. In this jurisdiction, autopsies are performed by a forensic pathologist. When potential cardiac disease is detected, the heart is referred to a cardiovascular pathologist. Furthermore, complete toxicological studies were performed whenever the cause of death was not evident or there was an indication that drugs may be contributory. A coroner, pathologist, and toxicologist participated in the adjudication process if toxicology was positive. A strength of this investigation was autopsy data on 82% of the deceased victims and an analysis of noncardiac diagnoses and medications either prescribed or detected. The final study population comprised 608 subjects who had a verified cardiac cause. The investigators found that 68% had a previously known cardiac diagnosis or had been prescribed a cardiac medication, 55% had ≥1 cardiovascular disease risk factor, and 20% had a psychiatric diagnosis or a prescribed psychotropic medication. The most frequent cardiac diagnosis was coronary heart disease (CHD) (40%), followed by structural disease of the myocardium (29%), whereas 16% were unexplained deaths. Most subjects with CHD were aged >35 years (52%), but of those aged 25 to 34 years, 16% had diagnosable CHD. The events were more common during sedentary activities (73%) and within private residences (72%). This study greatly broadens our understanding of the epidemiological characteristics of sudden cardiac death in the young. It is the largest complete assessment of the causes and associations related to SCA in the young. The upper age limit was extended to 45 years, instead of 35 years, to maximize the inclusion of inheritable heart disease. The population is skewed to the higher age group and, thus, provides data on an age bracket that is often combined with an older population. The thorough postarrest evaluation, including an admirable rate of high‐quality postmortem examinations, toxicology studies, and especially the inclusion of prescribed and over‐the‐counter medications, reveals that previous studies may have overestimated the frequency of undiagnosed heart disease.
