Evaluation of Electrical and Hemodynamic Effects of Different Pacing Strategies in CRT Candidates

Heart failure patients with delayed electrical activation of the heart often benefit from cardiac resynchronization therapy (CRT). However, traditional CRT using biventricular pacing is not effective in all patients. This study aims to evaluate the acute effects of pacing at different sites within the heart's conduction system-including His bundle pacing, deep septal pacing, left ventricular septal pacing, non-selective left bundle branch pacing, and selective left bundle branch pacing. We will assess how these pacing strategies improve electrical synchrony and heart function by analyzing ECG parameters, such as QRS duration and QRS area, and measuring hemodynamic response using left ventricular pressure changes. The goal is to identify which pacing site provides the best improvement in heart performance. The study includes patients with left bundle branch block or intraventricular conduction delay, reduced heart function (ejection fraction \<35%), and prolonged QRS duration (\>150 ms). This research may help improve the effectiveness of pacing therapy in heart failure patients who are not responding well to current CRT methods.

This is a prospective, single-center, crossover study designed to evaluate the acute hemodynamic and electrical effects of pacing at five distinct sites within the conduction system in patients with heart failure and wide QRS complexes. Each participant will undergo temporary pacing at the His bundle, deep septal, left ventricular septal, non-selective left bundle branch, and selective left bundle branch sites. Pacing sites will be confirmed by fluoroscopic guidance and intracardiac electrogram criteria, including stimulus-to-R' interval and QRS morphology. Hemodynamic response during each pacing mode will be assessed non-invasively using a Finometer device, which continuously measures beat-to-beat blood pressure and provides derived parameters of cardiac function. The primary objective is to compare the relative hemodynamic benefits and electrical synchrony achieved at each pacing location, with the aim of optimizing lead placement strategies for conduction system pacing in heart failure patients.