15 Jun Survival Benefit from Primary Prevention Implantable Cardioverter Defibrillators
MedicalResearch.com Interview with:
Daniel J. Friedman, MD
Duke University Hospital
Duke Clinical Research Institute
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.
MedicalResearch.com: What should clinicians and patients take away from your report?
Response: Primary prevention ICDs reduce sudden cardiac death among NYHA II and III patients. Primary prevention ICDs reduce all-cause mortality among NYHA II patients and are beneficial in many NYHA III patients.
Our findings generally support the ACC/AHA recommendation to implant a primary prevention ICD in NYHA III patients. However, our findings do underscore the importance of improved risk stratification and patient centered discussions for NYHA III patients who are candidates for a primary prevention ICD.
MedicalResearch.com: What recommendations do you have for future research as a result of this study?
Response: Future research is needed to improve risk stratification of NYHA III patients who are primary prevention ICD candidates due to a severely reduced EF. Optimal risk stratification will likely require consideration of clinical variables, biomarkers, myocardial substrate (e.g. scar), and inherited factors.
MedicalResearch.com: Is there anything else you would like to add?
Response: The Seattle Heart Failure Model and the Seattle Proportional Risk Model are risk prediction models for the prediction of all-cause mortality and sudden cardiac death, respectively, that have received recent attention via several recent high profile publications. Although these models may be useful in risk stratification of NYHA III ICD candidates, they require additional study before they can be routinely recommended for clinical care.
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New York Heart Association Class and the Survival Benefit from Primary Prevention Implantable Cardioverter Defibrillators: A Pooled Analysis of 4 Randomized Controlled Trials
American Heart Journal Available online 9 June 2017
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