In patients with dilated cardiomyopathy (DCM), worse prognosis was observed in relation to longer disease duration. Comorbidities were more frequent in long-standing heart failure (HF) than in recent-onset HF and were found to be related to worse outcomes. Over the last decades, survival has increased. Findings underscore the importance of careful attention to comorbid conditions in DCM cases.

• Researchers assessed the outcome and prognostic factors in patients with DCM and long-standing heart failure (LDCM) vs recent-onset heart failure (RODCM), using the Swedish Heart Failure Registry.

• This study included 2019 patients with RODCM and 1,714 patients with LDCM, analyzed for all-cause, cardiovascular (CV), and non-CV death and hospitalizations; heart transplantation; and a combined outcome of all-cause death, heart transplantation, or HF hospitalization.

• Compared with RODCM, all outcomes were more frequent in LDCM.

• The multivariable-adjusted hazard ratios (HRs) for LDCM vs RODCM were 1.56 for all-cause death over a median follow-up of 4.2 and 5.0 years, respectively; 1.67 for CV death; 2.12 for heart transplantation; 1.36 for HF hospitalization; and 1.37 for the combined outcome.

• Similar outcomes were obtained in a propensity score-matched analysis.

• CV death was the main reason of death in LDCM and was found to be higher in LDCM than in RODCM.

• LDCM was associated with significantly more frequency of almost all comorbidities than in RODCM, and the mean number of comorbidities rose significantly with raised duration of disease, also post-age adjustment.

• Factors that were prognostically adverse included age, New York Heart Association functional class, ejection fraction, and left bundle branch block.

• Diabetes was the only comorbidity linked with the combined outcome irrespective of HF duration, in LDCM [HR 1.34] and in RODCM [HR 1.29].

• Only in RODCM, male gender [HR 1.38] and aspirin use [HR 1.33] conferred an elevated risk.

• Only in LDCM, prognostically adverse factors included heart rate ≥75 b.p.m. [HR 1.20], atrial fibrillation [HR 1.24], musculoskeletal or connective tissue disorder [HR 1.36], and diuretic therapy [HR 1.40].