ICD Implantation in Patients with Nonischemic Heart Failure

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 (25^th-75^th 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.

Primary prevention implantable cardioverter-defibrillator and opportunities for sudden cardiac death risk assessment in non-ischaemic cardiomyopathy

Sudden cardiac death (SCD) accounts for approximately one-third of all deaths among patients with non-ischaemic cardiomyopathy (NICM). Implantable cardioverter-defibrillator (ICD) therapy has been the primary intervention for managing individuals at high risk for SCD. However, individual ICD trials in the NICM population have failed to demonstrate a mortality benefit with prophylactic ICD implantation. Current guidelines recommend ICD implantation in NICM patients with symptomatic heart failure and a left ventricular ≤35% and are based on meta-analyses of multiple trials that span three decades and include the recent Danish Study to Assess the Efficacy of ICDs in Patients with Non-ischaemic Heart Failure on Mortality (DANISH) trial. These pooled analyses report a significant reduction in all-cause mortality with ICD implantation compared with medical therapy alone. In addition, each of these trials has demonstrated consistently a reduction in the risk of SCD compared with medical therapy alone. As a result, a refined approach of risk stratification that selects patients at the highest risk for SCD may lead to a significant improvement in ICD efficacy. In this clinical review, we first discuss the evolution of clinical trials that have evaluated ICDs in the NICM population. We then highlight some key markers of arrhythmia risk that hold promise in personalizing risk stratification for SCD.

Should Primary Prevention ICDs Still Be Placed in Patients with Non-ischemic Cardiomyopathy? A Review of the Evidence

PURPOSE OF REVIEW

Recent evidence has suggested that implantable defibrillator (ICD) in non-ischemic cardiomyopathy (NICM) may not offer mortality benefit in the presence of guideline-directed medical therapy (GDMT) and cardiac resynchronization therapy (CRT).

RECENT FINDINGS

Despite significant benefits of GDMT and CRT, current evidence is derived from ICD trials that rely predominantly on reduced left ventricular ejection fraction alone (LVEF). The majority of patients with sudden cardiac death (SCD) have LVEF > 30% indicating that LVEF by itself is an inadequate predictor of SCD. The Danish study to assess the efficacy of ICD in patients with non-ischemic systolic heart failure on mortality (DANISH) highlights the importance of better risk stratifying NICM patients for ICD implantation. Assessment of life expectancy, comorbidities, presence of advanced heart failure, etiology of NICM, and the presence of myocardial fibrosis can help risk stratify ICD beyond LVEF. Genetics and biomarkers can be of further assistance in risk stratification.