Triple Chamber Pacing in Hypertrophic Obstructive Cardiomyopathy (HOCM) Patients - TRICHAMPION STUDY

This investigation is a prospective, randomized, single-blinded and multicenter design. The purpose of this study is to evaluate the benefit of atrial-synchronous biventricular (BiV) pacing in severely symptomatic hypertrophic obstructive cardiomyopathy (HOCM) patients with severe Left Ventricular Outflow Tract (LVOT) obstruction implanted with a Cardiac Resynchronization Therapy - Pacing (CRT-P) device. Randomization * Implant will be performed (CRT-P). * Patients will be randomized 1:1 to either Treatment Group (Optimized Biventricular (DDD) pacing) or Control Group (Back-up Atrial (AAI) pacing) during the first 12 months: * Treatment Group. The patient´s device is programmed to optimized DDD BiV pacing * Control Group. The patient´s device is programmed to back-up pacing AAI. * After 12 months, the patients initially randomized to the Treatment Group (Optimized DDD Pacing) will continue in the same group. The patients initially randomized to Control Group (AAI Back-up Pacing) will be changed to the Treatment Group (Optimized DDD Pacing). And all the patients will be followed 12 months more.