Author Interviews, Duke, Heart Disease / 15.06.2017
Survival Benefit from Primary Prevention Implantable Cardioverter Defibrillators
MedicalResearch.com Interview with:
Daniel J. Friedman, MD
Duke University Hospital
Duke Clinical Research Institute
Durham, NC
MedicalResearch.com: What is the background for this study? What are the main findings?
Response: Although primary prevention ICDs have saved countless lives among patients with heart failure and a reduced ejection fraction, the use of primary prevention ICDs in patients with more advanced heart failure [defined by New York Heart Association Class (NYHA)] is controversial.
Specifically, there are conflicting data from the pivotal primary prevention ICD trials regarding whether primary prevention ICDs reduce all-cause mortality among patients with a severely reduced ejection fraction (≤35%) and NYHA III heart failure.
We performed a patient level meta-analysis using data from 4 pivotal primary prevention ICD trials (MADIT-I, MADIT-II, SCD-HeFT, and DEFINITE) to assess whether primary prevention ICD efficacy varied by NYHA class (II vs. III). Overall, the ICD reduced all-cause mortality among the overall population of patients (NYHA II and III). We subsequently assessed ICD efficacy after stratification by NYHA class.
Among NYHA II patients, the ICD significantly reduced all-cause mortality by reducing sudden cardiac death. Although NYHA III patients randomized to an ICD experienced a significantly lower rate of sudden cardiac death, this did not translate into a reduction in all-cause mortality, due to competing causes of non-sudden death (which an ICD cannot treat). Based on relatively wide confidence intervals associated with the estimate for ICD effect in NYHA III patients, there appears to be substantial heterogeneity in outcomes among these patients. This suggests that many NYHA III patients can benefit from a primary prevention ICD, but further study is necessary to determine which NYHA III patients are poised to benefit.
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