Heart rate distribution in paced and non-paced patients with severe recurrent reflex syncope and tilt-induced asystole: Findings from the BIOSync CLS study. (15th July 2021)

• Record Type: Journal Article
• Authors: Russo, Vincenzo; Anguera, Ignasi; de Lange, Frederik J.; De Ruvo, Ermenegildo; Taieb, Jérôme; Zardini, Marco; Nigro, Gerardo; Giacopelli, Daniele; Gargaro, Alessio; Brignole, Michele
• Is Part Of: International journal of cardiology. Volume 335(2021)
• Page Start: 52
• Page End: 54
• Publication Date: 2021-07-15
• Subjects: Cardiac pacing -- Closed loop stimulation -- Heart rate -- Pacemaker -- Reflex syncope -- Tilt testing; bpm beats per minute -- CLS Closed Loop Stimulation -- DDD dual-chamber sequential pacing mode -- HR heart rate -- IQR interquartile range; Cardiology -- Periodicals; Electronic journals; 616.12
• DOI: 10.1016/j.ijcard.2021.04.032
• Languages: English
• ISSNs: 0167-5273

Abstract

Abstract: Background: Undiagnosed sinus or atrioventricular node dysfunction may bias estimation of the real efficacy of cardiac pacing in preventing vasovagal reflex syncope. We assessed this hypothesis in the BIOSync CLS trial which showed that dual-chamber pacing with closed loop stimulation (CLS) remarkably reduced recurrences of syncope. Methods and results: In the study patients aged 40 years or older with ≥2 episodes of loss of consciousness in the last year and an asystolic response to Tilt-Table test were randomized to pacing ON (DDD-CLS mode) or pacing OFF (ODO mode). We utilized the available pacemaker diagnostic data in a total of 103 patients (52 pacing ON, 51 pacing OFF) to generate cumulative distribution charts for heart rate (HR) and percentage of pacing. At 12 months, we did not find evidence of suspected sinus or atrioventricular node dysfunction. Beats were similarly distributed between groups ( p = 0.96), with an average HR of 76 ± 8 bpm (pacing ON) versus 77 ± 7 bpm (pacing OFF). In the active group, the median percentage of atrial and ventricular pacing was 47% and 0%, respectively. Intolerance to high pacing rates was reported in only one patient (1.6%) and was easily resolved by reprogramming the maximum CLS pacing rate. Conclusions: We did not find evidence of suspected sinus or atrioventricular node dysfunction in the BIOSync CLS patients. The benefit of pacing should be ascribed to pacing prevention of pure vasovagal episodes. CLS algorithm modulated pacing rates over a wide frequency range, consistently competing with sinus node. Highlights: If cardiac pacing prevents syncope, this may not be due to the vasovagal reflex. The ODO mode allowed collection of long-term profiles of spontaneous heart rate. No evidence of sinus or atrioventricular node dysfunction in the BIOSync patients. The benefit should be ascribed to pacing prevention of pure vasovagal episodes. CLS algorithm modulated pacing rates over a wide frequency range.