Effect of closed loop stimulation versus accelerometer on outcomes with cardiac resynchronization therapy: the CLASS...

Area of Science:

• Cardiology
• Electrophysiology
• Heart Failure Management

Background:

• Chronotropic incompetence (CI) is prevalent in heart failure with reduced ejection fraction (HFrEF) patients, correlating with poor exercise tolerance and outcomes.
• Cardiac resynchronization therapy (CRT) devices are used in HFrEF, but optimal pacing strategies for CI remain under investigation.

Purpose of the Study:

• To evaluate the impact of closed-loop stimulation (CLS) rate-adaptive pacing on functional capacity in HFrEF patients with CI.
• To compare CLS pacing against standard dual-chamber pacing (DDDR) in this patient population.

Main Methods:

• A randomized, blinded, cross-over trial design was employed.
• Patients with HFrEF and CI received Biotronik CRT-D devices.
• Participants underwent quality of life questionnaires, 6-minute walk distance (6MWD) tests, and cardiopulmonary exercise testing during two 1-week periods: CLS pacing and DDDR pacing.

Main Results:

• Nine patients (mean age 71.4 years, 7 NYHA Class III) were enrolled.
• Quality of life scores trended higher with CLS pacing (p=0.06).
• No significant differences were observed in 6MWD, peak heart rate, or peak VO2 between CLS and DDDR pacing. Submaximal testing was confirmed by low respiratory exchange ratios.

Conclusions:

• CLS pacing did not significantly improve peak heart rate, peak VO2, or 6MWD in HFrEF patients with CI compared to DDDR pacing.
• A trend towards improved quality of life was noted with CLS programming.
• A majority of patients (56%) preferred CLS pacing.