Closed-loop stimulation as a physiological rate-modulated pacing approach based on intracardiac impedance to lower the atrial tachyarrhythmia burden in patients with sinus node dysfunction and atrial fibrillation

Introduction: The effectiveness of rate-modulated pacing for the suppression of atrial fibrillation (AF) is controversial. Closed-loop stimulation (CLS) is a heart rate modulation technique based on the contractility of the right ventricle estimated by sensing myocardial impedance, and CLS can still adapt to the heart rate in conditions where there are no significant changes in acceleration or ventilation, such as emotional stress. We elucidated the association between CLS and atrial tachyarrhythmia (AT) burden in patients with sinus node dysfunction and paroxysmal AF history before pacemaker implantation. Methods and Results: We retrospectively reviewed all consecutive patients who underwent pacemaker implantation for sinus node dysfunction with an AF history before implantation. Overall, 146 patients were analyzed, with fixed-rate pacing (FP) in 82, CLS in 31, and non-CLS rate modulation in 33 patients. The AF/AT episodes were detected in 98 patients during a 12-month period. The median AF/AT burden was 1.6% (interquartile: 0.0%, 11.0%) in FP; 0% (0.0%, 2.5%) in CLS, and 1.0% (0.1%, 9.3%) in non-CLS. The AF/AT burden was significantly lower for CLS than for FP and non-CLS rate modulation (P <.01 and P =.04, respectively). CLS was associated with lower risks of AF/AT occurrence (hazard ratio [HR], 0.31; P =.02) and AF/AT burden more than 5% (HR, 0.28; P =.05), even after adjusting for potential confounders. This association was independent of the percentage of atrial pacing. Conclusion: CLS was associated with lower AF/AT burden after pacemaker implantation in patients with sinus node dysfunction and AF history.