Overview

High burden right ventricular (RV) pacing has been shown to increase cardiovascular mortality, incidence of heart failure (HF), worsen left ventricular (LV) function and accelerate the development of atrial fibrillation (AF). High percentage ventricular pacing and wider paced QRS in the setting of normal baseline LV ejection fractions have consistently been shown to be independent risk factors for pacing-induced cardiomyopathy. Left bundle branch pacing (LBBP) has emerged as a potential alternative pacing mechanism that may avoid LV dyssynchrony and pacing-induced LV dysfunction by mimicking native electrical conduction.

Eligibility

Inclusion Criteria:

1. Age ≥ 18 years
2. Patients with an ejection fraction of >35%
3. Patients with an indication for ventricular pacing and high-degree atrioventricular block where the degree of anticipated RV pacing is >90% including:
   1. Third degree AV block
   2. Symptomatic or asymptomatic second-degree AV block
   3. First degree AV block ≥ 280ms with a narrow QRS, or ≥ 240ms with an intraventricular delay (QRS duration ≥120ms)
4. Echocardiogram within the last 3 months, with ability to have DICOM images

Exclusion Criteria:

1. Indication for an implantable cardioverter defibrillator
2. Presence of a mechanical tricuspid valve
3. Any prior attempt at implantation of an ICD, CRT, HBP, or LBBP
4. Lack of capacity to consent
5. Other serious medical condition with life expectancy of <2 years
6. Pregnancy
7. Patients in whom the conduction system abnormality is expected to be transient or recover over time
8. Patients with permanent atrial fibrillation