P1917Can cryoballoon ablation produce alterations in cardiac and extra-cardiac autonomic nervous system in patients with atrial fibrillation?

Abstract

Abstract Background Cryoballoon ablation (CBA) during pulmonary vein isolation (PVI) for atrial fibrillation (AF) can cause direct thermal injury to structures adjacent to the left atrium, including the periatrial ganglionated plexi (GP). In contrast, it has not been clarified whether cardiac autonomic nervous system (CANS) modification by CBA could indirectly affect extra-CANS. Purpose This study was aimed to investigate the impact of CBA on extra-CANS as well as CANS in AF patients. Methods Ninety-three Consecutive patients who underwent initial CBA in our institute were enrolled. Among them, 64 subjects (age 67±9 years; male gender 52%; CHADS2 score 1.2±1.0; diabetes mellitus 16%; β-blocker therapy 23%) had paroxysmal AF (G-P) and 29 (age 66±7 years; male gender 90%; CHADS2 score 1.3±1.0; diabetes mellitus 24%; β-blocker therapy 34%) had sustained AF (G-S). In G-P, resting sinus heart rate (R-HR) and coefficient of variation of the R-R intervals (CVR-R) during sinus rhythm were measured in resting 12-lead electrocardiogram before and after CBA as an index of CANS. Decrease in CVR-R after PVI reflects the vagal nerve injury by the procedure. Pupil movement reflects the autonomic nervous function. In both groups, pupillary light reflex, as an indicator of extra-CANS activity, was measured by infrared videopupillography (Iriscorder® Dual C10641, Hamamatsu Photonics, Hamamatsu, Japan) before and after CBA. Velocity of dilatation (VD) is related to sympathetic function, and velocity of contraction (VC) is associated with the balance between sympathetic and vagal tone. All CBA were treated with second generation 28mm cryoballoons (CB). CB temperature was down to a minimum of −60°C and target application time was 180 seconds. Results Complete PVI was achieved in all patients, in which touch-up radiofrequency ablation for the PVI was required in 4 cases of G-S. In G-P, R-HR significantly increased (59.2±9.2bpm to 72.5±8.3bpm, p<0.01) and CVR-R significantly decreased (2.32±1.1% to 1.61±0.61%, p<0.01) after CBA, while VC and VD did not significantly change (3.83±1.03mm2/sec to 3.64±0.96mm2/sec and 1.83±0.62mm2/sec to 1.86±0.84mm2/sec, respectively). In G-S, there were not significant changes between before and after CBA in VC and VD (3.77±0.80mm2/sec to 3.71±0.99mm2/sec and 1.81±0.49mm2/sec to 1.80±0.59mm2/sec, respectively). There were no significant differences between two groups in VC and VD before the procedure. Conclusion These results suggest that CBA seems to result in local parasympathetic denervation due to damage of adjacent structures including ganglionated plexi while the alteration of CANS by CBA does not seem to efferently affect extra-CANS.