BackgroundWhen used in appropriately selected heart failure (HF) patients, cardiac resynchronization therapy (CRT) reduces mortality and hospitalization. It is not understood whether CRT implantation during hospitalization for HF is associated with similar benefits.HypothesisTiming of CRT implantation relative to hospitalization for HF is associated with clinical outcomes.MethodsThis analysis included patients eligible for CRT and discharged alive between January 2005 and December 2012 from 388 hospitals in Get With The Guidelines-HF. Participants were linked with Centers for Medicare and Medicaid Services data to evaluate outcomes of all-cause mortality and HF re-hospitalization based on CRT status (present on admission, placed during hospitalization, and prescribed at discharge; reference = no CRT).ResultsOf 15 619 CRT-eligible HF patients, 2408 (15%) had CRT on admission, 1269 (8%) underwent CRT implantation during hospitalization and 643 (4%) had CRT prescribed at discharge. Compared with patients without CRT, mortality was lower in those who received CRT implantation during HF hospitalization (adjusted hazard ratio [HR] 0.63; P < 0.0001) and those prescribed CRT at discharge (adjusted HR 0.78; P = 0.048). A reduction in HF re-hospitalization was observed in patients with CRT implanted during hospitalization (adjusted HR 0.64; P < 0.0001), but not in those who were prescribed CRT at discharge (adjusted HR 1.02; P = 0.77).ConclusionCRT implantation during HF hospitalization was associated with lower rates of mortality and HF re-hospitalization. These data suggest that a CRT utilization strategy that does not delay implantation to the post-discharge period may be appropriate. Randomized data are needed to definitively identify optimal timing of CRT implantation