Sudden cardiac death in young adults: a contemporary 5 year observational cohort study from a tertiary cardiology center

Background

Sudden cardiac death (SCD) in young individuals remains a major public health concern, characterised by heterogeneous mechanisms and limited contemporary real-world data on prognostic determinants.

Purpose

To characterise clinical features, aetiological substrates and outcomes of sudden cardiac arrest (SCA) in patients aged <50 years.

Methods

We conducted a retrospective observational study including consecutive SCA cases between 2020 and 2025 in a European cardiology tertiary centre. Traumatic deaths, definite non-arrhythmic structural cardiovascular causes (e.g. cardiac tamponade, aortic dissection, pulmonary embolism) and extracardiac causes were excluded.

Results

A total of 121 patients with SCA were included from 224 identified cases aged <50 years. Mean age was 41.6±8.2 years, with a marked male predominance (78.5%). Resuscitated SCA accounted for 54.5%, while 45.5% resulted in SCD. Ventricular fibrillation (VF) was the most frequent presenting rhythm (63.3%), followed by asystole (23.3%), pulseless electrical activity (7.5%) and pulseless ventricular tachycardia (5.8%). Survival was significantly higher in patients presenting with shockable compared with non-shockable rhythms (χ²(3)=37.58, p<0.001), with a large effect size (Cramer’s V=0.56).

Coronary angiography was performed in 85.1% of patients, echocardiography in 98.3% (mean LVEF 37.3±14.7%), cardiac magnetic resonance imaging in 5.8%, and genetic testing in 4.95%. An ischaemic substrate was identified in 62.0% of cases, predominantly acute coronary syndromes (93.3%). Non-ischaemic substrates accounted for 28.9%, including dilated cardiomyopathy (13.2%), hypertrophic cardiomyopathy (3.3%), arrhythmogenic right ventricular cardiomyopathy (2.5%), primary electrical diseases (8.3%) and myocarditis (0.8%), while 9.1% had idiopathic SCA. Cardiac substrate was significantly associated with survival after SCA (χ²(2)=6.64, p=0.036), with the highest survival in idiopathic SCA (73%), intermediate survival in ischaemic heart disease (60%) and the lowest in non-ischaemic substrates (37%). In multivariable logistic regression including age quartile, LVEF quartile and ischaemic aetiology, no variable reached conventional statistical significance; however, LVEF >35% was associated with lower odds of death (OR 0.37, 95% CI 0.13–0.98, p=0.051), while non-ischaemic aetiology showed increased mortality (OR 5.28, 95% CI 1.03–30.57, p=0.052). Implantable cardioverter-defibrillators were used for secondary prevention in 20.2%.

Conclusion

In young adults with SCA, presenting rhythm was the strongest determinant of outcome, while aetiology and LVEF showed relevant prognostic associations. The substantial heterogeneity of substrates and the limited use of advanced diagnostic tools highlight important gaps in post-arrest evaluation and support the need for prospective studies.For image description, please refer to the figure legend and surrounding text.Aetiology and survival Sankey diagramFor image description, please refer to the figure legend and surrounding text.