Outcomes with physiologic His bundle pacing in patients with narrow QRS complex.

Area of Science:

• Cardiology
• Electrophysiology
• Medical Devices

Background:

• Ventricular and biventricular pacing in narrow QRS complex patients increases cardiac risks.
• Ventricular pacing avoidance algorithms do not mitigate these risks due to nonphysiologic atrioventricular (AV) delays.

Purpose of the Study:

• To evaluate outcomes in narrow QRS complex patients undergoing His bundle pacing.
• To assess the impact of maintaining normal paced QRS morphology and physiologic AV delays.

Main Methods:

• 196 patients with narrow QRS (92 ± 10 ms) underwent His bundle pacing.
• Pacemakers programmed for physiologic AV delays and rate response, with 3-year follow-up.

Main Results:

• His bundle pacing maintained normal QRS parameters and achieved 92% pacing burden.
• Significant improvement in left ventricular function and reduction in dilation/mitral regurgitation in patients with reduced ejection fraction.
• Normal ejection fraction patients maintained function without new valvular issues.

Conclusions:

• His bundle pacing with normal QRS morphology and physiologic AV delays is safe in narrow QRS patients.
• Associated with low mortality (10% at 3 years) and improved echocardiographic parameters.
• Paced QRS morphology and AV delays are key factors for future conduction system pacing trials.