Sex Differences in Long-Term Outcomes With Cardiac Resynchronization Therapy in Mild Heart Failure Patients With Left Bundle Branch Block

Background: previous studies have shown conflicting results regarding the benefit of cardiac resynchronization therapy (crt) by sex and qrs duration.methods and results: in the multicenter automatic defibrillator implantation trial with cardiac resynchronization therapy (madit-crt),we evaluated long-term clinical outcome of heart failure (hf) or death,death,and hf alone by sex and qrs duration (dichotomized at 150 ms) in left bundle-branch block patients with crt with defibrillator backup (crt-d) versus implantable cardioverter-defibrillator (icd) only. there were 394 women (31%) and 887 men with left bundle-branch block. during the median follow-up of 5.6 years,women derived greater clinical benefit from crt-d compared with implantable cardioverter-defibrillator only,with a significant 71% reduction in hf or death (hazard ratio [hr] 0.29,p<0.001) and a 77% reduction in hf alone (hr 0.23,p<0.001) compared with men,who had a 41% reduction in hf or death (hr 0.59,p<0.001) and a 50% reduction in hf alone (hr 0.50,p<0.001) (all sex-by-treatment interaction p<0.05). men and women had similar reduction in long-term mortality with crt-d versus implantable cardioverter-defibrillator only (men: hr 0.70,p=0.03; women: hr 0.59,p=0.04). the incremental benefit of crt-d in women for hf or death and hf alone was consistent with qrs <150 or >150 ms.conclusions: during long-term follow-up of mild hf patients with left ventricular dysfunction and wide qrs,both women and men with left bundle-branch block derived sustained benefit from crt-d versus implantable cardioverter-defibrillator only,with significant reduction in hf or death,hf alone,and all-cause mortality regardless of qrs duration. there is an incremental benefit with crt-d in women for the end points of hf or death and hf alone.clinical trial registration: url: https://clinicaltrials.gov/. unique identifiers: nct00180271,nct01294449,and nct02060110. © 2015 the authors. published on behalf of the american heart association,inc.,by wiley blackwell.