Sandhu A, Bao H, Minges KE, et al. - In this population-based study, researchers investigated how the 2012 American College of Cardiology/American Heart Association/Heart Rhythm Society guideline update of the 2008 guidelines for device-based therapy has influenced the use of cardiac resynchronization therapy defibrillator (CRT-D). From the National Cardiovascular Data Registry for implantable cardioverter-defibrillators, all patients undergoing new CRT-D implantations from January 1, 2012, to December 31, 2015, were included. During the study period, a rise was seen in the rates of guideline-concordant CRT-D implantation. At a minority of hospitals, the major fraction of guideline-discordant implants were clustered. They also found the correlation of conduction abnormalities, especially non–left bundle branch block and nonspecific intraventricular conduction delay, with guideline-discordant implants.