Impact of Atrio-ventricular Optimization With His Bundle Pacing on Treatment of Atrio-ventricular Dromotropathy

Impact of Atrio-ventricular Optimization With His Bundle Pacing on Treatment of Atrio-ventricular Dromotropathy

This study aims to determine the clinical and hemodynamic benefit of atrio-ventricular (AV) resynchronization with His bundle pacing in patients with symptomatic first degree AV block.

The term AV dyssynchrony was introduced by Salden F. and coauthors in 2018. It stands for the adverse effects of AV dyssynchrony due to PR interval prolongation. According to the ESC and ACC guidelines, severe first degree AV block is an IIa indication for permanent pacemaker implantation, yet data on these patients' clinical outcomes are scarce. To independently determine the impact of AV resynchronization, His bundle pacing will be used to avoid intraventricular desynchronization.

Symptomatic patients with severe first-degree AV block and echocardiographically proven AV dyssynchrony will be included in the study.

All patients will receive a dual-chamber pacemaker with an atrial lead positioned in the right atrium and ventricular lead placed on the bundle of His. In a single-blind cross-over design, patients will be randomized to AV sequential His bundle pacing with echo-guided AV optimization or back-up VVI pacing mode. Each study period will last for three months. At the end of both periods, cardiopulmonary exercise testing, complete echocardiographic study, and clinical evaluation will be performed.

Peak oxygen uptake and echocardiography-based hemodynamic parameters in both periods will be compared.

Inclusion Criteria:

• First OR second degree Mobitz type 1 atrioventricular block with a PR interval > 250 ms
• left ventricular ejection fraction > 50%
• echocardiographic criteria of atrioventricular dyssynchrony (diastolic filling time/RR interval ratio < 0,4 OR fusion of E and A waves OR diastolic mitral regurgitation)
• symptoms on exertion (dyspnea, palpitations)
• insufficient shortening of PR interval during exercise (PR interval > 200 ms at heart rate of 100 beats per minute)

Exclusion Criteria:

• left ventricular ejection fraction < 50%
• third degree atrioventricular block
• atrial fibrillation
• sinus node disease
• left bundle branch block
• right bundle branch block
• ventricular arrhythmia that indicates implantation of cardioverter defibrillator
• consumption of drugs that influence atrioventricular conduction
• active bacterial infection
• inability to undergo cardiopulmonary exercise test
• anaemia (haemoglobin concentration < 100 g/L)
• pregnancy