ICDs as Prophylaxis in Patients with Cardiomyopathy?

Summary and Comment |
July 5, 2017

ICDs as Prophylaxis in Patients with Cardiomyopathy?

  1. Mark S. Link, MD

Implantable cardioverter-defibrillators reduce mortality — in specific patient populations.

  1. Mark S. Link, MD

Based on the DANISH study (NEJM JW Cardiol Oct 2016 and N Engl J Med 2016; 375:1221), some cardiologists have questioned the benefit of implantable cardioverter-defibrillators (ICDs) for primary prevention in both nonischemic and ischemic cardiomyopathies (CMs). To learn more, researchers performed a meta-analysis using 11 randomized, controlled trials (4 on 1781 patients with nonischemic CM; 6 on 4414 patients with ischemic CM; 1 on 2521 patients with either disease type).

The mean left ventricular ejection fraction (LVEF) was 26%; almost all patients had New York Heart Association heart failure class II or III. Compared with conventional care, ICDs were associated with reduced all-cause mortality overall (hazard ratio [HR], 0.81); this effect was significant for nonischemic CM (P=0.006) but not for ischemic CM (P=0.063). Compared with antiarrhythmic agents, ICDs reduced all-cause mortality but significantly so only for ischemic CM (P=0.002; nonischemic CM, P=0.071). Not surprisingly, the risk for sudden cardiac death (SCD) was reduced in patients with ICDs. Mortality was not affected by sex, age, LVEF, heart failure class, and QRS duration, but ICD use did interact with diabetes and myocardial infarction (MI): ICDs placed in diabetes patients did not reduce mortality, but ICDs placed >18 months after MI lowered mortality. ICD placement soon after coronary-artery bypass grafting or MI did not reduce mortality.

Comment

ICDs reduce SCD, but that is all they do. In patients with an SCD risk that is not outweighed by comorbidities, ICDs will probably reduce overall mortality. In patients with high competing mortality risks, ICDs will likely not decrease overall mortality. As this meta-analysis shows us, our current indications for ICD implantation should not be altered by the DANISH study. But we should use the art of medicine wisely; not all patients with a LVEF ≤35% benefit from ICDs.

Editor Disclosures at Time of Publication

  • Disclosures for Mark S. Link, MD at time of publication Editorial boards UpToDate; Heart Rhythm; Circulation; EP Lab Digest Leadership positions in professional societies Heart Rhythm Society (Chair, CME Compliance Committee); American Heart Association (Chair, ACLS Writing Group; Member, Emergency Cardiovascular Care)

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