Clinical Research Directory

Inclusion Criteria: * Subject meets current ACC/AHA/HRS guidelines for implantation of a CRT-D device. * Subject has documented LVEF ≤ 35% within 60 days of enrollment. * Subject meets the criteria for presence of Strauss-defined LBBB. * Subject meets NYHA classification II or III. * Subject is willing and able to provide written consent. * Subject is at least 18 years of age at the time of consent. * Subject is geographically stable and willing and able to complete study procedures, including follow-up visits. * The subject's medical records must be accessible by the enrolling site over the follow-up period. Exclusion Criteria: * Subject has documented myocardial infarction before enrollment. * Subject has non-LBBB conduction patterns such as Right Bundle Branch Block (RBBB) or non-specific IVCD. * Subject has 2nd or 3rd degree AV block. * Subject has persistent or permanent atrial fibrillation (AF) or atrial flutter (AFL). * Subject has intrinsic (non-paced) QRS duration ≤ 120ms. * Subject with previous or existing pacemaker (including transvenous and transcatheter pacing system), Implantable Cardioverter Defibrillator (ICD, transvenous) or CRT-D (transvenous) device or leads. * Subject has contraindications for screw-in transvenous lead placement (e.g., mechanical right heart valve). * Subject underwent valve surgery within 90 days prior to enrollment. * Subject is unable or unwilling to undergo baseline CMR imaging, if previously collected CMR images are unavailable or do not meet minimum acceptable criteria. * Subject is post-heart transplantation or is actively listed on the transplantation list. * Subject is implanted with a left ventricular assist device (LVAD). * Subject has severe renal disease. * Subject is on continuous or uninterrupted infusion (inotropic) therapy for heart failure. * Subject has complex and uncorrected congenital heart disease. * Subject has life expectancy of less than 12 months. * Subject is pregnant or breastfeeding. * Subject is enrolled or planning to enroll in a concurrent clinical study that may confound the results of this study, without documented pre-approval from a Medtronic study manager.