Conduction System Pacing With Left Bundle Branch Pacing as Compared to Standard Right Ventricular Pacing

LEFT Bundle Pacing vs Standard Right Ventricular Pacing for Heart Failure

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.

We hypothesize that in patients with high degree AV block with anticipated ventricular pacing >90%, and an EF >35% patients undergoing LBBP will demonstrate a significantly lower number of the primary composite endpoint of cardiovascular death, heart failure events, and change in LVESVi as compared to standard RV pacing. Echos will be performed at baseline, 12, 24, and 36 months. NTproBNPs are performed at baseline and follow-up. There will be a core echo lab, and blinded adjudication of ECGs and events.

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