Changes in the optimal cardiac resynchronization therapy pacing configuration during physiologic stress.

Area of Science:

• Cardiology
• Electrophysiology
• Heart Failure Management

Background:

• Some heart failure patients experience persistent symptoms despite cardiac resynchronization therapy (CRT).
• QRS prolongation during exercise in these patients suggests suboptimal CRT settings under stress.
• Investigating dynamic CRT optimization during physiological stress is crucial for improving patient outcomes.

Purpose of the Study:

• To determine if the optimal CRT pacing configuration (OPC) changes during dobutamine-induced stress.
• To assess the impact of dynamic CRT configuration changes on left ventricular (LV) contractility.

Main Methods:

• Seven patients undergoing CRT implantation had invasive LV dP/dTmax measured.
• Ten pacing configurations were tested to identify the optimal baseline pacing configuration (OPC).
• Measurements were repeated during dobutamine infusion to identify the stress OPC and compare LV dP/dTmax.

Main Results:

• The optimal CRT pacing configuration differed between baseline and dobutamine stress in 6 out of 7 patients.
• LV dP/dTmax significantly improved with the dobutamine OPC compared to baseline OPC during stress (p < 0.001).
• The mean increase in LV dP/dTmax from baseline to stress OPC was 13%, while QRS duration and morphology remained stable.

Conclusions:

• The optimal CRT pacing configuration is dynamic and can change during dobutamine-induced physiological stress.
• LV and RV activation timing did not significantly change, indicating that electrical conduction patterns were stable.
• Automated, dynamic adjustments to CRT pacing based on physiological conditions warrant further investigation for heart failure management.