Sudden cardiac death in younger adults: a comparative analysis of coronary and non-coronary causes

Abstract

Aims We aimed to characterize etiologies and outcomes of patients aged 16–65 years after resuscitated sudden cardiac death (SCD), with particular emphasis on non-coronary and idiopathic cases. Methods This retrospective single-center study screened admissions from 2010 to 2021 using ICD-10 codes followed by manual chart review. Patients were classified as having coronary, non-coronary, or unclassified etiology. Follow-up of hospital survivors included chart review, structured interviews, and device interrogation where available. Results Of 232 patients meeting the initial inclusion criteria, 187 had sufficient diagnostic information for etiological classification: 139 had coronary and 48 non-coronary causes, while 45 remained unclassified because early death or incomplete diagnostic information precluded reliable assignment. In the classified cohort, 136 patients (72.7%) experienced out-of-hospital cardiac arrest. Coronary artery disease accounted for 94.2% of coronary cases. In the non-coronary group, 54.2% remained idiopathic; identified causes included cardiomyopathies (29.2%), myocarditis (8.3%), and channelopathies (6.3%). CPR duration <10 min was associated with lower in-hospital mortality, whereas duration ≥60 min was associated with higher mortality. Of 118 hospital survivors, structured follow-up was completed in 74 patients (median 77 months). ICD implantation was more frequent in non-coronary than coronary cases (68.8% vs. 18.7%). Among 47 patients with device follow-up, appropriate ICD shocks occurred in 23.1% and 19.0%, respectively. Conclusions Non-coronary and idiopathic etiologies represent a substantial proportion of SCD in younger adults. The high proportion of unexplained cases supports standardized post-arrest evaluation, including multimodality imaging, inherited arrhythmia assessment, genetic testing, family screening, and longitudinal expert review. Recurrent ventricular arrhythmias in both groups support ICD-based secondary prevention in selected survivors.