LAUSR

Heart failure (HF) represents a major cause of morbidity and health care expenditure globally,1 and increases the risk for sudden cardiac death (SCD). In the USA, about 325 000 adults die from SCD every year, accounting for half of all cardiovascular deaths.2 The implantable cardioverter-defibrillator (ICD) is currently indicated for primary SCD prophylaxis in patients with severe left ventricular systolic dysfunction, irrespective of the underlying aetiology.3,4 The recent results of the Danish Study to Assess the Efficacy of ICDs in Patients with Non-Ischaemic Systolic Heart Failure on Mortality (DANISH)5 raised novel interest in the longstanding debate on the efficacy of ICD implantation in non-ischaemic dilated cardiomyopathy (NIDCM). In fact, the DANISH study found only a slightly lower, non-statistically significant (P= 0.28) reduction in the primary endpoint of all-cause mortality in NIDCM patients randomized to ICD implantation (21.6%) compared with the control group (23.4%) treated with optimal medical management but no ICD implantation over a median follow-up of 67.6 months (Figure 1A). These results add further evidence to the findings of previous studies with conflicting results, such as the Sudden Cardiac Death in Heart Failure Trial (SCD-HeFT)6 and the Defibrillators in Non-Ischaemic Cardiomyopathy Treatment Evaluation (DEFINITE) study.7 In order to resolve this still debated issue, in-depth analyses of these studies are required to disentangle the reasons underlying the differences observed across the results of individual studies. In fact, although the authors of the DANISH study concluded that ICD implantation is not associated with an overall survival benefit in patients with NIDCM,5 perusal of the secondary endpoints shows that the frequency of SCD was almost halved in the ICD arm (4.3% vs. 8.2%; P= 0.005) (Figure 1B). This latter finding raises doubts about the current strategy of defibrillator implantation for the primary prevention of SCD. In fact, although not statistically significant, hazard ratios (HRs) for all-cause death and cardiovascular death were 0.87 and 0.77, respectively, both in favour of ICD implantation.5 However, the benefits to be gained from ICD use should be weighed against the risks for complications and side effects. Moreover, the differential impact of ICD on different modes