For patients with systolic heart failure that was not caused by ischemic heart disease, implanting prophylactic implantable cardioverter-defibrillators (ICDs) did not reduce the long-term rate of death of any cause compared with patients who did not receive an ICD, according to a randomized trial.

However, a subgroup analysis found that the rate of death from any cause was significantly lower (36 percent lower) in patients younger than 68 years old compared with those who were 68 or older. The researchers mentioned that the effect of ICD implantation was independent of cardiac resynchronization therapy status.

Lead researcher Lars Køber
, MD, of University Hospital, Blegdamsve in Copenhagen, Denmark, and colleagues published their results online in the New England Journal of Medicine on Aug. 28.

The findings were also presented at the European Society of Cardiology’s Congress in Rome.

Although guidelines in the U.S. and Europe have given ICDs a class 1 recommendation for patients with heart failure and reduced left ventricular systolic function, the researchers noted the evidence for ICDs is stronger for patients with ischemic heart disease than for patients with heart failure from other causes.

In this trial, known as DANISH (Danish Study to Assess the Efficacy of ICDs in Patients with Non-ischemic Systolic Heart Failure on Mortality), the researchers enrolled 1,116 patients with symptomatic non-ischemic systolic heart failure at five centers in Denmark at which ICDs were implanted. The study was supported by unrestricted grants from Medtronic, St. Jude Medical, TrygFonden and the Danish Heart Foundation.

Patients were enrolled from Feb. 7, 2008, to June 30, 2014, and randomly assigned in a 1:1 ratio to the ICD group or the control group. At baseline, the groups were well balanced, and 58 percent of patients in each group received CRT.

In the ICD group, the median time from randomization to implantation was 31 days. Four patients required two attempts at implantation, while 14 patients did not receive an ICD for various reasons. In addition, 27 patients in the control group received an ICD: 24 because of an arrhythmic event and three at the request of their physician.

After a median follow-up period of 67.6 months, 21.6 percent of patients in the ICD group and 23.4 percent of patients in the control group died. Patients in the ICD group had a 13 percent reduction in death from any cause, but the difference was not statistically significant.

Cardiovascular death occurred in 13.8 percent of patients in the ICD group and 17 percent of patients in the control group, which was not significantly different. Meanwhile, sudden cardiac death occurred in 4.3 percent of patients in the ICD group and 8.2 percent of patients in the control group, which was significantly different.

“All time-to-event curves appeared to diverge during the initial 5 years of the trial and then to converge,” the researchers wrote. “Post hoc analysis of annual event rate ratios supports this interpretation. This observation lends support to the rationale for long-term studies, since the most common causes of death may change over time in patients with heart failure.”