BackgroundCurrent guidelines recommend implantable cardioverter defibrillators for the primary prevention of sudden cardiac death (SCD) in patients with dilated cardiomyopathy with left ventricular ejection fraction (LVEF)≤35%. However, its effectiveness is hindered by the inability to reliably discriminate between the risk of SCD and competing death of heart failure deterioration, thereby limiting its clinical utility. We aimed to refine the SCD risk stratification model based on cardiac magnetic resonance imaging for patients with dilated cardiomyopathy with LVEF≤35%.MethodsA total of 1272 patients with dilated cardiomyopathy with LVEF≤35% who underwent cardiac magnetic resonance imaging were consecutively enrolled in this study. The primary end point is a composite of SCD or aborted SCD and the second end point is a composite of heart failure death and heart transplantation.ResultsOver a median follow-up of 86.3 months, 101 patients reached the primary end point. In the adjusted analysis, age (hazard ratio [HR], 1.02 [95% CI, 1.01-1.04]; P=0.006) years, a family history of SCD (HR, 2.00 [95% CI, 1.01-3.98]; P=0.05), NT-proBNP (N-terminal pro-B-type natriuretic peptide) (HR, 2.02 [95% CI, 1.18-3.44]; P=0.01), LVEF (per 5% HR, 0.79 [95% CI, 0.66-0.95]; P=0.01), and late gadolinium enhancement≥7.5% (HR, 4.11[95% CI, 2.72-6.21]; P<0.001) were associated with SCD or aborted SCD. Left atrial volume index≥68.3 mL/m2 was an independent predictor of the secondary end point (adjusted HR, 1.65 [95% CI, 1.13-2.40]; P=0.009). Compared with late gadolinium enhancement<7.5%, patients with late gadolinium enhancement≥7.5% and LVEF≤20% had a 7.12-fold higher risk of experiencing SCD events in competing Cox analysis (annual event rate, 4.8%).ConclusionsPatients with dilated cardiomyopathy with late gadolinium enhancement≥7.5% were at heightened risk of SCD events, which can be used for risk assessment. Risk stratifications for SCD, combining clinical and cardiac magnetic resonance imaging may potentially guide decision-making for implantable cardioverter defibrillator therapy.