QT sensing rate responsive pacing compared to fixed rate ventricular inhibited pacing: a controlled clinical study

Area of Science:

• Cardiology
• Biomedical Engineering
• Clinical Electrophysiology

Background:

• Symptomatic high-degree atrioventricular (AV) block often necessitates pacemaker implantation.
• Traditional fixed-rate ventricular inhibited (VVI) pacing may not adequately address physiological rate variations.
• Rate-responsive (TX) pacing aims to optimize heart rate response to activity and stress.

Purpose of the Study:

• To compare the efficacy and patient preference of rate-responsive (TX) pacing versus fixed-rate (VVI) pacing.
• To evaluate the impact of pacing modes on exercise tolerance, symptoms, and well-being.
• To assess physiological heart rate variability during daily activities and stress.

Main Methods:

• Double-blind, cross-over study involving 18 patients with high-degree AV block.
• Comparison of TX mode versus VVI mode over one-month periods.
• Daily symptom diaries, exercise testing, mental stress tests, and 24-hour Holter monitoring were utilized.

Main Results:

• TX mode significantly increased heart rate during exercise and improved exercise tolerance by 9%.
• Patients reported significantly less dyspnea and fatigue with TX pacing at comparable workloads.
• Eleven patients preferred TX mode, reporting improved general well-being, while two preferred VVI due to angina exacerbation.

Conclusions:

• Rate-responsive (TX) pacing is generally preferable to VVI pacing for patients with high-degree AV block.
• Careful patient selection is advised due to potential worsening of angina or rapid rate oscillations in some individuals.
• TX pacing demonstrates improved physiological adaptation and patient-reported outcomes.