ICD for primary prevention cuts death in cardiomyopathy
Use of implantable cardioverter defibrillator (ICD) for primary prevention significantly reduces all-cause mortality compared with conventional care for patients who had heart failure with reduced ejection fraction (HFrEF), according to a meta-analysis.
The meta-analysis included 8,716 patients with nonischaemic (n=4,414) or ischaemic (n=2,521) cardiomyopathy or both (n=1) from 11 randomized clinical trials which compared ICD therapy with conventional care in the primary prevention setting. [Ann Intern Med 2017;167:103-111]
After a mean follow-up of 3.2 years, all-cause mortality was significantly reduced by 19 percent with ICD therapy compared with conventional care (hazard ratio [HR], 0.81; p=0.043). The results remained when the analysis was stratified by nonischaemic or ischaemic disease, although statistical significance was nullified in the latter.
The reduction in all-cause mortality was driven by a 59 percent decline in the risk of sudden death in patients with ICD placement compared with those receiving conventional care (HR, 0.41; p=0.001), regardless of whether it was nonischaemic (HR, 0.44; p=0.064) or ischaemic disease (HR, 0.39; p=0.012).
“[The survival benefit with ICD] was independent of age, sex, symptoms, systolic function, and QRS duration but was not observed when implantation occurred within 40 days after myocardial infarction [MI] or immediately after elective coronary bypass surgery,” observed the researchers.
“This agrees with previous data that indicated a statistically significant mortality reduction with ICD therapy vs conventional care 18 months or longer after MI,” they added.
The difference in statistical significance between nonischaemic and ischaemic disease might be attributed to the fewer patients with nonischaemic disease in the studies analysed, or the lower incidence of sudden death in patients with nonischaemic vs ischaemic disease, according to the researchers.
No significant difference in noncardiac and any cardiac deaths was observed between the two treatment groups.
Why the study was done
“In clinical practice, ICDs have been regarded as a mainstay of treatment for the primary prevention of sudden cardiac death in patients with sustained ventricular tachycardia or ventricular fibrillation not due to reversible causes developing more than 48 hours after ST-segment elevation MI,” wrote the researchers.
“They are also used in selected patients who have a left ventricular ejection fraction of 35 percent or less at least 40 days after MI and NYHA* class II or III symptoms, or a left ventricular ejection fraction of 30 percent or less and NYHA class I symptoms while receiving guideline-based therapy and an expected survival of more than 1 year,” they continued.
The current study supports the value of primary-prevention ICD in patients with cardiomyopathy, after controversy arose from the DANISH** trial which showed no long-term survival benefit in patients with nonischaemic, symptomatic HFrEF. [N Engl J Med 2016;375:1221-1230]
The benefits of prophylactic ICD appear consistent in both ischaemic and nonischaemic cardiomyopathy in the current study, noted the researchers, who said, “Ongoing studies will provide further insights into the role of ICD therapy, specifically in older patients and in relation to concomitant percutaneous coronary intervention vs optimal medical therapy.”