Risk Factors of Sudden Cardiac Death in the Young: Multiple-Year Community-Wide Assessment

Abstract

Background: Prevention of sudden cardiac arrest (SCA) in the young remains a largely unsolved public health problem, and sports activity is an established trigger. Although the presence of standard cardiovascular risk factors in the young can link to future morbidity and mortality in adulthood, the potential contribution of these risk factors to SCA in the young has not been evaluated.

Methods: We prospectively ascertained subjects who experienced SCA between the ages of 5 and 34 years in the Portland, Oregon, metropolitan area (2002-2015, catchment population ≈1 million). We assessed the circumstances, resuscitation outcomes, and clinical profile of subjects who had SCA by a detailed evaluation of emergency response records, lifetime clinical records, and autopsy examinations. We specifically evaluated the association of standard cardiovascular risk factors and SCA, and sports as a trigger for SCA in the young.

Results: Of 3775 SCAs in all age groups, 186 (5%) occurred in the young (mean age 25.9±6.8, 67% male). In SCA in the young, overall prevalence of warning signs before SCA was low (29%), and 26 (14%) were associated with sports as a trigger. The remainder (n=160) occurred in other settings categorized as nonsports. Sports-related SCAs accounted for 39% of SCAs in patients aged ≤18, 13% of SCAs in patients aged 19 to 25, and 7% of SCAs in patients aged 25 to 34. Sports-related SCA cases were more likely to present with shockable rhythms, and survival from cardiac arrest was 2.5-fold higher in sports-related versus nonsports SCA (28% versus 11%; P=0.05). Overall, the most common SCA-related conditions were sudden arrhythmic death syndrome (31%), coronary artery disease (22%), and hypertrophic cardiomyopathy (14%). There was an unexpectedly high overall prevalence of established cardiovascular risk factors (obesity, diabetes mellitus, hypertension, hyperlipidemia, smoking) with ≥1 risk factors in 58% of SCA cases.

Conclusions: Sports was a trigger of SCA in a minority of cases, and, in most patients, SCA occurred without warning symptoms. Standard cardiovascular risk factors were found in over half of patients, suggesting the potential role of public health approaches that screen for cardiovascular risk factors at earlier ages.

Keywords: death, sudden, cardiac; epidemiology; heart arrest; population; prevention & control; risk factors; sports.

Figure 1. Sports-related SCA as a proportion of total SCA in different age groups

Overall, 86% of SCA in age <35 years occurred in a nonsports setting. SCA indicates sudden cardiac arrest.

Figure 2. Initial rhythm recorded during presentation with sudden cardiac arrest

Shockable rhythm (VF/VT) was significantly more common among sports-related than non-sports SCAs. Among the subset of 21 sports-related and 105 nonsports-related cases with resuscitation attempted in the field, 18 sports-related and 92 nonsports-related cases had initial rhythm available from ECG recordings in the field or from EMS reports. PEA indicates pulseless electrical activity; SCA, sudden cardiac arrest; VF, ventricular fibrillation; and VT, ventricular tachycardia.

Figure 3. Prevalence of established cardiovascular risk factors in young subjects who experienced SCA

Information regarding cardiovascular disease (CVD) risk factors was available for 174 patients with SCA, whereas BMI was available for 136 patients. Total CVD risk factors (diabetes mellitus, hyperlipidemia, hypertension, smoking, obesity) were calculated among the latter subset. BMI indicates body mass index; and SCA, sudden cardiac arrest.