Long-term Follow-up of the The Danish Study to Assess the Efficacy of ICDs in Patients with Non-ischemic Systolic Heart Failure on Mortality (DANISH).

Background: The Danish Study to Assess the Efficacy of Implantable Cardioverter-Defibrillators (ICDs) in Patients with Non-ischemic Systolic Heart Failure on Mortality (DANISH) found that primary-prevention ICD implantation was not associated with an overall survival benefit in patients with non-ischemic systolic heart failure during a median follow-up of 5.6 years, though there was a beneficial effect on all-cause mortality in patients ≤70 years. This study presents an additional four years of follow-up data from DANISH. Methods: In DANISH, 556 patients with non-ischemic systolic heart failure were randomized to receive an ICD and 560 to receive usual clinical care and followed until June 30, 2016. In this long-term follow-up study, patients were followed until May 18, 2020. Analyses were conducted for the overall population and according to age (≤70 and >70 years). Results: During a median follow-up of 9.5 years (25th-75th percentile, 7.9-10.9 years), 208/556 patients (37%) in the ICD group and 226/560 patients (40%) in the control group died. Compared with the control group, the ICD group did not have significantly lower all-cause mortality (HR 0.89 [95%CI,0.74-1.08]; P=0.24). In patients ≤70 years (n=829), all-cause mortality was lower in the ICD group than the control group (117/389 [30%] vs 158/440 [36%]; HR 0.78 [95%CI,0.61-0.99]; P=0.04), whereas in patients >70 years (n=287), all-cause mortality was not significantly different between the ICD and control group (91/167 [54%] vs 68/120 [57%]; HR 0.92 [95%CI,0.67-1.28]; P=0.75). Cardiovascular death showed similar trends (overall, 147/556 [26%] vs 164/560 [29%], HR 0.87 [95%CI,0,70-1.09], P=0.20; ≤70 years, 87/389 [22%] vs 122/440 [28%], HR 0.75 [95%CI,0.57-0.98], P=0.04; >70 years, 60/167 [36%] vs 42/120 [35%], HR 0.97 [95%CI,0.65-1.45], P=0.91). The ICD group had a significantly lower incidence of sudden cardiovascular death in the overall population (35/556 [6%] vs 57/560 [10%]; HR 0.60 [95%CI,0.40-0.92]; P=0.02) and in patients ≤70 years (19/389 [5%] vs 49/440 [11%]; HR 0.42 [95%CI,0.24-0.71]; P=0.0008), but not in patients >70 years (16/167 [10%] vs 8/120 [7%]; HR 1.34 [95%CI,0.56-3.19]; P=0.39). Conclusions: During a median follow-up of 9.5 years, ICD implantation did not provide an overall survival benefit in patients with non-ischemic systolic heart failure. In patients ≤70 years, ICD implantation was associated with a lower incidence of all-cause mortality, cardiovascular death, and sudden cardiovascular death. Clinical Trial Registration: URL: https://www.clinicaltrials.gov. Unique identifier: NCT00542945.