Abstract 3527: Is There an Association Between Beta Blocker Dose and Clinical Outcomes With CRT? Insights From the COMPANION Study
Introduction: Cardiac resynchronization therapy (CRT) has been studied with a background of optimal pharmacologic therapy (OPT) including beta blockers (BB). Although CRT has been shown to improve hospitalization and mortality, the influence of BB dose has not been fully explored. We sought to explore the relationship between CRT and BB dose on outcomes in the COMPANION study.
Methods: Patients (pts) were randomized to OPT alone or in combination with CRT, with and without defibrillation. Pts were stratified into three groups: pts achieving a BB target dose of at least 50 mg/day of carvedilol or equivalent (BBTar), pts taking BB but below the target dose (BBSubTar), and pts on no BB (BBNone). Clinical outcomes (all-cause mortality alone and in combination with cause-specific hospitalization) were compared with a Cox proportional hazards model adjusted for differences in baseline characteristics.
Results: Of 1520 pts, 498 (33%) had BBNone, 734 (48%) had BBSubTar, and 288 (19%) had BBTar. Outcomes are summarized below:
Conclusions: In COMPANION, retrospective analysis within each treatment arm suggest that event rates improve with greater BB use. Analysis between treatment arms demonstrated significant improvement with CRT across all outcomes for BBSubTar pts. BBNone and BBTar pts had directionally favorable improvements with CRT but did not achieve significance. Since BB use and dosage was not randomized, this association might be a marker for ability to tolerate BB and should be interpreted cautiously. More work is needed to clarify the role of BB dose and CRT.