- Design
- Rapid systematic review and meta-analysis of randomised trials
- Population
- Six RCTs of patients with nonischaemic HFrEF
- Primary outcome
- Sudden cardiac death, cardiovascular and all-cause mortality
- Effect
- SCD RR 0.41 (0.26–0.65); CV death RR 0.75 (0.59–0.95); all-cause RR 0.88 (0.72–1.07)
A rapid systematic review and meta-analysis pooled six pivotal randomised trials of primary-prevention ICDs in nonischaemic HFrEF.
ICDs lowered sudden cardiac death (RR 0.41) and cardiovascular death (RR 0.75), both rated high certainty. All-cause mortality was not significantly lower (RR 0.88, 95% CI 0.72–1.07). Trials with shorter follow-up showed a mortality benefit, which is consistent with background therapy improving over time and leaving less sudden death to prevent.
That pattern fits the debate since DANISH: in a patient on full modern therapy, competing non-sudden deaths dilute the device's effect. The decision is individual — age, comorbidity, scar on MRI and response to treatment all weigh in.
- Optimise guideline-directed medical therapy for at least three months before deciding on an ICD.
- Weigh age and competing causes of death, which narrow the benefit.
- Consider cardiac MRI for scar when the decision is close.
- Discuss with the patient that the device prevents sudden death rather than extending life overall.
Why it matters
The case for a routine ICD weakens as medical therapy reduces the sudden deaths it exists to prevent.
Don't overread it
The mortality benefit with shorter follow-up is a subgroup result and should not be taken as the headline.
The statistics, in plain English
An RR of 0.88 with an interval from 0.72 to 1.07 crosses 1, so the data are compatible with a modest benefit or none. The subgroup split by follow-up length is hypothesis-generating.
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