Findings indicate that late-onset dilated cardiomyopathy could represent a specific subgroup of patients and favor the use of extensive genetic testing in older patients as it could offer crucial etiologic and prognostic information.

• In this cohort study of 184 patients with late-onset dilated cardiomyopathy, the prevalence, type, and prognostic effect of disease-related rare variants were determined.

• A total of 66 patients (36%) were identified to be carriers of a pathogenic or likely pathogenic (P/LP) variant.

• Most prevalent were titin-truncating variants (present in 46 [25%] of the total population and accounting for 46 [69%] of all genotype-positive patients).

• A median (interquartile range) follow-up of 42 (10-115) months revealed deaths of 23 patients (13%); 17 (25%) of these were carriers of P/LP variants, while 6 patients (5.1%) were genotype-negative.

• Higher mortality was noted in patients with a positive genetic test vs genotype-negative patients.

• Relative to the current epidemiology, findings demonstrated a high genetic variation burden, largely because of titin-truncating variants.