Abstract 15602: Left Bundle Branch Block Predicts Better Survival in Women than Men Receiving Cardiac Resynchronization Therapy: Long Term Follow-Up of 145,000 Patients
Background: Left bundle branch block (LBBB) predicts clinical benefit from cardiac resynchronization therapy defibrillators (CRT-D). Prior studies have suggested that 1/3 of patients diagnosed with LBBB by conventional ECG criteria may not have true LBBB, and this misclassification occurs more frequently in men than women. We tested the hypothesis that conventional diagnosis of LBBB predicts better survival in women than men due to fewer false positive diagnoses.
Methods: We analyzed Medicare records from 144,642 patients who received a CRT-D device between 2002- 2008 and were followed for up to 7.5 years. Medicare billing data was used to assess age, gender, race and 10 comorbidities (LBBB, RBBB, MI, HTN, ischemic cardiomyopathy, diabetes, AF, stroke, history of HF hospitalization and Charlson score). We calculated multivariable hazard ratios (HR) to determine if conventional LBBB diagnosis had different prognostic significance in women and men.
Results: After 6 years of follow up, 60% of patients had died. LBBB diagnosis and female gender predicted lower mortality, however the survival benefit portended by LBBB differed by gender. In univariate analysis, LBBB predicted a 31% reduction in death in women (HR=0.69, [0.67-0.71]), but only a 16% reduction in death in men (HR=0.84, [0.82-0.85]). Controlling for comorbidities, LBBB still predicted a 26% reduction in death in women (HR=0.74, [0.71,0.77]) compared to a 15% reduction in death in men (HR=0.85, [0.83,0.87]). A significant interaction (p<0.0001) between gender and LBBB further supported that conventional diagnosis of LBBB has a different meaning in women and men.
Conclusions: LBBB diagnosis predicts greater survival in women than men receiving CRT and this discrepancy is not explained by differences in comorbidities. This may be because LBBB has different prognostic significance by gender, however we hypothesize that it is due to men having more false positive LBBB diagnoses by conventional ECG criteria.
- © 2012 by American Heart Association, Inc.