Use of Cardiac Resynchronization Therapy Defibrillator in US Hospitals.

Importance: Cardiac resynchronization therapy (CRT) provides significant reduction in morbidity and mortality in select patients with left ventricular systolic dysfunction and specific parameters of electrocardiographic evidence of dyssynchrony. Relative to the 2012 American College of Cardiology/American Heart Association/Heart Rhythm Society guideline update for patient selection, little is known about the contemporary use of CRT in the United States. Objective: To describe the use of CRT defibrillator (CRT-D) in the period around guideline revision. Design, Setting, and Participants: All patients undergoing new CRT-D implantations in the National Cardiovascular Data Registry for implantable cardioverter-defibrillators from January 1, 2012, to December 31, 2015, at 1710 participating hospitals were identified for this population-based study. Rates of CRT-D implantation that were concordant and discordant with the 2012 American College of Cardiology/American Heart Association/Heart Rhythm Society update of the 2008 guidelines for device-based therapy were determined. Analysis began in January 2012. Main Outcomes and Measures: Increase in guideline-concordant CRT-D implantation. Results: Among 135 253 patients undergoing initial CRT-D implantation, 88 923 were included in the study cohort, of which 73 859 implants (83.1%) were guideline concordant. The proportion of guideline-concordant devices increased from 81.2% (16 710 of 20 481) in 2012 to 84.2% (20 515 of 24 356) in 2015 (P for trend < .001). Significant clustering was noted with 33% (565 of 1710) of hospitals accounting for greater than 70% (10 545 of 15 065) of guideline-discordant CRT-D implants. Conduction abnormalities, in particular, underlying right bundle branch block (3597 [23.9%] vs 7425 [10.1%]; P < .001) and nonspecific intraventricular conduction delay (3341 [22.2%] vs 4769 [6.5%]; P < .001) were more common in those who received guideline-discordant devices. Conclusions and Relevance: Rates of guideline-concordant CRT-D implantation increased during the study. The major fraction of guideline-discordant implants were clustered at a minority of hospitals. Conduction abnormalities, particularly non-left bundle branch block and nonspecific intraventricular conduction delay, correlated with guideline-discordant implants indicating continued opportunity for dissemination and understanding of guideline updates.