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31-08-2016 | Cardiology | News | Article

ICDs fail to reduce long-term mortality in non-ischaemic HF

medwireNews: Prophylactic implantable cardioverter–defibrillator (ICD) use does not reduce long-term mortality in patients with symptomatic heart failure (HF) not caused by coronary artery disease, Danish research shows.

The 556 study participants who were randomly assigned to receive an ICD did, however, have a significant 50% reduction in the risk of sudden death compared with the 560 participants who were assigned to receive usual clinical care.

All patients had symptomatic non-ischaemic systolic HF with a left ventricular ejection fraction of 35% or lower at the start of the study.

Lars Køber (Rigshospitalet, Copenhagen) and colleagues say their findings add “to the available body of data to consider in formulating the indications for ICD implantation in patients with non-ischemic systolic heart failure”, particularly as current American Heart Association guidelines do not distinguish between patients with ischaemic and non-ischaemic HF when recommending ICD implantation.

During a median follow-up period of 67.6 months, the all-cause mortality rate was 21.6% in the ICD group and 23.4% in the control group, a difference that was not statistically significant.

There was also no significant difference in cardiovascular deaths between the ICD and control groups, at 13.8% and 17.0%, respectively, but there were significantly fewer sudden cardiac deaths among patients who received an ICD compared with those who did not, at 4.3% versus 8.2%.

Køber et al say in The New England Journal of Medicine that ICD implantation had a “convincing” effect on sudden cardiac death, suggesting that “patients who are not expected to die from other causes may be good candidates for ICD implantation.”

Of note, 58% of patients in each group received cardiac resynchronisation therapy (CRT), nearly all were treated with ACE inhibitors or angiotensin-receptor blockers and ß blockers, and almost 60% received a mineralocorticoid-receptor antagonist.

This high level of background treatment may partly explain the lack of significant benefit in overall mortality, says John McMurray, from the University of Glasgow, UK, in an accompanying editorial.

“[T]hese treatments reduce the risk of premature cardiovascular death, including the risk of sudden cardiac death, very substantially”, he explains.

But the researchers point out that the effect of ICD implantation was independent of CRT status.

By contrast, subgroup analyses showed that age had a significant effect on treatment. Specifically, all-cause mortality was significantly lower in patients under 68 years of age who received an ICD, compared with those of the same age who did not.

McMurray concludes that ICDs are “expensive and not without adverse effects”, meaning they should be targeted to “patients most likely to benefit — that is, those who remain at high absolute risk for sudden cardiac death despite receiving the best available pharmacologic and device therapy.”

By Laura Cowen

medwireNews is an independent medical news service provided by Springer Healthcare Limited. © Springer Healthcare Ltd; 2016