# Atrioventricular Delay Optimization in His‐Optimized Cardiac Resynchronization Therapy: A Case Report

## TL;DR

This case report shows how optimizing atrioventricular delay in a specific heart pacing technique improved outcomes for a patient with severe heart failure.

## Contribution

The report demonstrates the effectiveness of His-bundle optimized CRT with AV delay adjustment in non-responders to conventional CRT.

## Key findings

- AV delay optimization in HOT-CRT led to QRS narrowing and improved heart function in a non-responding patient.
- Individualized AV delay adjustment enhanced hemodynamic function and clinical stability over 15 months.
- HOT-CRT is particularly beneficial for patients with prolonged PR interval and intraventricular conduction delay.

## Abstract

His bundle pacing (HBP) has recently emerged as a physiologic pacing strategy that preserves ventricular synchrony and may improve outcomes in patients with heart failure and conduction abnormalities. Optimization of the atrioventricular (AV) delay plays a pivotal role in ensuring hemodynamic efficiency in patients with conduction system pacing. We report a 41‐year‐old male with dilated cardiomyopathy and severe heart failure (NYHA class IV, EF 16%), who was initially implanted with a cardiac resynchronization therapy (CRT) device. Despite multiple attempts to reposition the right and left ventricular leads, QRS duration during biventricular pacing widened from 140 to 185 ms. The right ventricular lead was subsequently repositioned to the His bundle (His‐optimized CRT, HOT‐CRT). Following AV delay optimization, the QRS duration narrowed to 120 ms, improving hemodynamic function. At 15‐month follow‐up, the patient remained clinically stable, able to perform moderate physical activity, with an improved EF of 25% and no recurrence of ventricular tachycardia. HOT‐CRT combines the physiologic advantage of His bundle pacing with optimized AV conduction timing, which is particularly valuable in patients with prolonged PR interval and nonresponse to conventional CRT. AV delay optimization ensures proper atrioventricular synchrony, enhances left ventricular filling, and contributes to improved cardiac output. This case highlights the significance of individualized AV delay adjustment in conduction system pacing to maximize therapeutic outcomes. Optimization of AV delay is essential for maximizing the benefits of conduction system pacing, especially in HOT‐CRT recipients. Attention to QRS morphology and duration during device implantation can help identify patients who will benefit most from individualized AV programming.

HOT‐CRT with individualized AV delay optimization can rescue patients who fail conventional CRT, particularly those with prolonged PR interval and intraventricular conduction delay. Dramatic QRS narrowing and hemodynamic improvement highlight the value of tailored conduction–system pacing strategies.