Mintu P. Turakhia et al. JACEP 2016;2:426-433 Derivation of Study Cohort Patients implanted with St. Jude Medical (SJM) cardiac resynchronization therapy with defibrillator (CRT-D) devices from November 30, 2011, to May 31, 2013, were identified. Patients whose sex was known, who were between 18 and 89 years of age, and who were identified as de novo to CRT were divided into quadripolar and bipolar groups. A subset of these patients was included in remote monitoring records and used for left ventricular (LV) lead deactivation analysis. A further subset of these patients was used for percent biventricular (%BiV) pacing analysis. Mintu P. Turakhia et al. JACEP 2016;2:426-433 American College of Cardiology Foundation