Left Bundle Area Versus Selective His Bundle Pacing (LEFTBASH): Single Center, Open Label, Randomized Pilot Study to Evaluate Capture Thresholds and Acute Echocardiographic Hemodynamic Characteristics

This is a single center, open label, prospective randomized pilot study to evaluate the capture threshold of His Bundle versus left bundle area pacing. Secondary analysis will focus on changes in left ventricular performance and mechanical synchrony. Symptomatic bradyarrhythmias are effectively treated with cardiac pacemakers.The amount of pacing by the lead positioned in the bottom chamber of the heart at traditional sites such as the right ventricular apex have been associated with increased rates of atrial fibrillation, heart failure, and mortality. Traditional pacing sites result in cardiac electromechanical dyssynchrony, for which alternate pacing sites to minimize these untoward effects have been sought. HIS bundle pacing, which utilizes a patient's native conduction, has demonstrated improved electrical synchrony and left ventricular function when compared to traditional pacing at the tip of the bottom chamber. Barriers to wide spread application to this technique include the His bundle anatomic location and its attendant difficulties associated with implant, as well as higher capture thresholds leading to decreased battery duration of the pacemaker. An alternative to HIS bundle pacing is placing the lead just past the HIS bundle area, which is further in the heart, and to actively fixate the lead into the interventricular septum. This is referred to as Left Bundle Pacing, as it may electrically capture the left bundle, which would simulate a patient's native conduction. The researchers will evaluate the two different pacing sites (HIS bundle and Left Bundle area sites) to determine how effectively the heart pumps with each pacing site.

Patients requiring pacemaker implant will be screened for study eligibility and approached for informed consent. Baseline assessments including echocardiogram and ECG will be obtained. A standard of care echo done within 3 months of the procedure will be used as the baseline echo. Once enrolled, the researchers will randomize patients to one of two arms. One arm will fixate the ventricular pacemaker lead to the HIS bundle area while the other arm will have the leads fixed into the left bundle area. The pacemaker wires will be connected in accordance with randomization group. The day after the procedure, a chest x-ray, EKG and pacemaker evaluation will be performed. An echocardiogram will be obtained at 3 months post procedure. At 6 and 12 months post procedure, EKG rhythm strips will be obtained from patients' standard of care remote pacemaker monitoring systems.