Right Ventricular Septal Pacing in Patients With Right Bundle Branch Block and Heart Failure (The SPARK Trial)

Inclusion Criteria

• •Cardiomyopathy; ischemic or non-ischemic on optimal medical therapy per current heart failure treatment guidelines for at least 3 months.
• •LVEF \< 35% by trans-thoracic echocardiogram assessment
• •Prior implantation of pacemaker/defibrillator with at least an atrial and RV mid septal lead. Atrial lead can be waived if RV lead has atrial sensing capabilities\*
• •Normal sinus rhythm at enrollment
• •RBBB with QRS duration \>120 msec on 12 lead surface EKG.
• •PR interval \<250 msec on 12 lead surface EKG
• •* Subjects with biventricular pacemaker/ICD will be eligible for enrollment if their LV lead pacing function has been turned off by the subject's primary cardiologist prior to study enrollment for at least 3 months (this could be due to lead malfunction or the decision to deactivate the LV pacing therapy for any reason per primary cardiologist discretion)