Heart rate distribution in paced and non-paced patients with severe recurrent reflex syncope and tilt-induced asystole: Findings from the BIOSync CLS study

AbstractBackground Undiagnosed sinus or atrioventricular node dysfunction may bias estimation of the real efficacy cardiac pacing in preventing vasovagal reflex syncope. We assessed this hypothesis BIOSync CLS trial which showed that dual-chamber with closed loop stimulation (CLS) remarkably reduced recurrences Methods and results In study patients aged 40 years older ?2 episodes loss consciousness last year an asystolic response to Tilt-Table test were randomized ON (DDD-CLS mode) OFF (ODO mode). utilized available pacemaker diagnostic data a total 103 (52 ON, 51 OFF) generate cumulative distribution charts for heart rate (HR) percentage pacing. At 12 months, we did not find evidence suspected dysfunction. Beats similarly distributed between groups (p = 0.96), average HR 76 ± 8 bpm (pacing ON) versus 77 7 OFF). active group, median atrial ventricular was 47% 0%, respectively. Intolerance high rates reported only one patient (1.6%) easily resolved by reprogramming maximum rate. Conclusions patients. The benefit should be ascribed prevention pure episodes. algorithm modulated over wide frequency range, consistently competing node.