Heart Failure: Some Women May Benefit More Than Men from CRT-D Therapy

MedicalResearch.com Interview with:
David Strauss, M.D., Ph.D., Senior Author
Medical Officer
Center for Devices and Radiological Health
U.S. Food and Drug Administration, Silver Spring, Md

MedicalResearch: What are the main findings of the study?

Dr. Strauss: The underrepresentation of women in clinical trials for cardiac resynchronization therapy (CRT) devices, as with other devices, has made it difficult to assess differences in the safety and effectiveness of these devices for women vs. men. The FDA is exploring the potential of pooling and analyzing data from multiple trials to bridge the knowledge gap for certain subpopulations (such as women) often underrepresented in medical device clinical trials. By conducting one such meta-analysis, the FDA found that women benefit from cardiac resynchronization therapy (CRT) significantly more than men do.

MedicalResearch: Were any of the findings unexpected?

Dr. Strauss: Prior studies have suggested that patients with a left bundle branch block (electrical conduction disorder of the heart) benefit most from cardiac resynchronization therapy, and patients with a longer QRS duration (time for electrical activation of the heart, represented by the large wave seen on an ECG recording) of 150 milliseconds or more benefit most from CRT. However, the prior studies were not able to thoroughly investigate this effect separately in women and men. This was difficult to do because women only represented approximately 20 percent of the patients in each clinical trial. By pooling data from multiple trials we were able to increase the number of patients to answer specific questions about cardiac resynchronization therapy in women.

MedicalResearch: What should clinicians and patients take away from your report?

Dr. Strauss: In this combined analysis of 3 large CRT trials in patients with mild heart failure, we found that women benefit from cardiac resynchronization therapy significantly more than men do. Patients of both sexes with a left bundle branch block (LBBB) benefited. However, women did so at a shorter QRS duration than men (130 milliseconds in women vs. 150 milliseconds in men). In the patients with LBBB and shorter QRS duration, women had a 76 percent reduction in heart failure or death, while there was no significant benefit in men. In patients with a LBBB and a longer QRS duration, both women and men benefited from CRT. These findings are important to communicate because women are less likely than men to receive CRT.

MedicalResearch: What recommendations do you have for future research as a result of this study?

Dr. Strauss: This research highlights that sex-specific analysis is important in research studies.  Combining patient-level data from multiple clinical trials to investigate outcomes and performance in subpopulations, especially in underrepresented groups, is encouraged and should be done more often.

Later this summer, the FDA intends to finalize a guidance document that provides a clear framework for how to analyze and communicate data on women in medical device trials.

The FDA also intends to release an Action Plan that contains recommendations for improving the completeness and quality of analyses of data on women, as well as other populations, in summaries of product safety and effectiveness data and in labeling.


Cardiac Resynchronization Therapy in Women: US Food and Drug Administration Meta-analysis of Patient-Level Data
Robbert Zusterzeel MD, Kimberly A. Selzman MD, MPH, William E. Sanders MD, MBA, Daniel A. Caños PhD, MPH, Kathryn M. O’Callaghan BSE, Jamie L. Carpenter MSPH, Ileana L. Piña MD, MPH, David G. Strauss MD, PhD

JAMA Intern Med. 2014;174(8):-. doi:10.1001/jamainternmed.2014.2717


Last Updated on December 21, 2014 by Marie Benz MD FAAD