Autonomic Alterations After Pulmonary Vein Isolation in the CIRCA‐DOSE (Cryoballoon vs Irrigated Radiofrequency Catheter Ablation) Study

Background The natural history of autonomic alterations following catheter ablation of drug-refractory paroxysmal atrial fibrillation is poorly defined, largely because of the historical reliance on non-invasive intermittent rhythm monitoring for outcome ascertainment. Methods and Results The study included 346 patients with drug-refractory paroxysmal atrial fibrillation undergoing pulmonary vein isolation using contemporary advanced-generation ablation technologies. All patients underwent insertion of a Reveal LINQ (Medtronic) implantable cardiac monitor before ablation. The implantable cardiac monitor continuously recorded physical activity, heart rate variability (measured as the SD of the average normal-to-normal), daytime heart rate, and nighttime heart rate. Longitudinal autonomic data in the 2-month period leading up to the date of ablation were compared with the period from 91 to 365 days following ablation. Following ablation there was a significant decrease in SD of the average normal-to-normal (mean difference versus baseline of 19.3 ms; range, 12.9-25.7; P<0.0001), and significant increases in daytime and nighttime heart rates (mean difference versus baseline of 9.6 bpm; range, 7.4-11.8; P<0.0001, and 7.4 bpm; range, 5.4-9.3; P<0.0001, respectively). Patients free of arrhythmia recurrence had significantly faster daytime (11±11 versus 8±12 bpm, P=0.001) and nighttime heart rates (8±9 versus 6±8 bpm, P=0.049), but no difference in SD of the average normal-to-normal (P=0.09) compared with those with atrial fibrillation recurrence. Ablation technology and cryoablation duration did not influence these autonomic nervous system effects. Conclusions Pulmonary vein isolation results in significant sustained changes in the heart rate parameters related to autonomic function. These changes are correlated with procedural outcome and are independent of the ablation technology used. Registration URL: https://www.clinicaltrials.gov; Unique identifier: NCT01913522.