Objective The recent Danish Study to Assess the Efficacy of ICDs in Patients with Non-ischemic Systolic Heart Failure on Mortality (DANISH) trial suggested that implantable cardioverter defibrillators (ICDs) do not reduce overall mortality in patients with non-ischaemic cardiomyopathy (NICM), despite reducing sudden cardiac death. We performed an updated meta-analysis to examine the impact of ICD therapy on mortality in NICM patients.
Methods A systematic search for studies that examined the effect of ICDs on outcomes in NICM was performed. Our analysis compared patients randomised to an ICD with those randomised to no ICD, and examined the endpoint of overall mortality.
Results Six primary prevention trials and two secondary prevention trials were identified that met the pre-specified search criteria. Using a fixed-effects model, analysis of primary prevention trials revealed a reduction in overall mortality with ICD therapy (RR 0.76, 95% CI 0.65 to 0.91).
Conclusions Although our updated meta-analysis demonstrates a survival benefit of ICD therapy, the effect is substantively weakened by the inclusion of the DANISH trial—which is both the largest and most recent of the analysed trials—indicating that the residual pooled benefit of ICDs may reflect the risk of sudden death in older trials which included patients treated sub-optimally by contemporary standards. As such, these data must be interpreted cautiously. The results of the DANISH trial emphasise that there is no ‘one size fits all’ indication for primary prevention ICDs in NICM patients, and clinicians must consider age and comorbidity on an individual basis when determining whether a defibrillator is appropriate.
- Implanted Cardiac Defibrillators
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Contributors The authors have reviewed and approved the submission of this manuscript. This manuscript is original and is not under consideration for publication elsewhere. Specifically, SB performed the analysis and drafted the manuscript. PJ contributed to the analysis and reviewed the manuscript. CJ, RG and JMcM reviewed and revised the manuscript. JMcM is responsible for the overall content as guarantor.
Funding This work was not funded and there was no role of any funding source in the conception, data synthesis, analysis, interpretation, or in drafting of the manuscript.
Competing interests SB and RG have received a research grant and consulting fees from Abbott Laboratories. RG has received consulting fees from Boston Scientific. CJ, PJ and JMcM have no competing interests to declare.
Provenance and peer review Commissioned; externally peer reviewed.