Author + information
- Received December 17, 2012
- Revision received March 4, 2013
- Accepted March 6, 2013
- Published online June 1, 2013.
- Zak Loring, BS∗,†,
- Daniel A. Caños, MPH∗,
- Kimberly Selzman, MD, MPH∗,‡,
- Naomi D. Herz, BS∗,
- Henry Silverman, BS§,
- Thomas E. MaCurdy, PhD§,
- Christopher M. Worrall, BS‖,
- Jeffrey Kelman, MD, MMSc‖,
- Mary E. Ritchey, PhD∗,
- Ileana L. Piña, MD, MPH∗,¶ and
- David G. Strauss, MD, PhD∗∗ ()
- ↵∗Reprint requests and correspondence:
Dr. David G. Strauss, FDA, Center for Devices and Radiological Health, 10903 New Hampshire Avenue, WO 62-1126, Silver Spring, Maryland 20993.
Objectives The goal of this study was to test the hypothesis that in recipients of cardiac resynchronization therapy defibrillators (CRT-D), conventional left bundle branch block (LBBB) diagnosis predicts better survival in women than in men.
Background New York Heart Association class I and II patients without LBBB do not benefit from CRT-D, and women have better survival after CRT-D than men. Separate analysis suggests that QRS duration thresholds for LBBB diagnosis differ according to sex, and conventional LBBB electrocardiographic criteria are falsely positive in men more frequently than in women.
Methods We analyzed Medicare records from 144,642 CRT-D recipients between 2002 and 2008 that were followed up for up to 90 months. Medicare billing data were used to determine age, sex, race, and comorbidities. Hazard ratios (HRs) were calculated to assess if conventional LBBB diagnosis had different prognostic significance according to sex.
Results In univariate analysis, LBBB was associated with a 31% reduction in death in women (HR: 0.69 [95% confidence interval (CI): 0.67 to 0.71]) but only a 16% reduction in death in men (HR: 0.84 [95% CI: 0.82 to 0.85]). In multivariable analyses controlling for comorbidities, LBBB was associated with a 26% reduction in death in women (HR: 0.74 [95% CI: 0.71 to 0.77]) and a 15% reduction in death in men (HR: 0.85 [95% CI: 0.83 to 0.87]). A significant interaction (p < 0.0001) between sex and LBBB was seen.
Conclusions LBBB diagnosis is associated with greater survival in women than in men receiving CRT-D, and this discrepancy is not explained by differences in measured comorbidities. Possible explanations for this difference include that LBBB may have different prognostic significance according to sex or that LBBB diagnosis is more often false-positive in men compared with women.
This project was supported by the Centers for Medicare & Medicaid Services/U.S. Food and Drug Administration (FDA) SafeRx Project and the FDA Office of Women's Health. All authors have reported that they have no relationships relevant to the contents of this paper to disclose.
- Received December 17, 2012.
- Revision received March 4, 2013.
- Accepted March 6, 2013.
- American College of Cardiology Foundation