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.

Implantable cardiac monitor after cryptogenic stroke: atrial fibrillation detection and predictors

Objective The main objective of our study was to analyze the incidence and predictors of atrial fibrillation (AF) in patients with cryptogenic stroke (CS) who received an implantable cardiac monitor (ICM) at our Institution. Methods From November 2013 to October 2017, a total of 133 patients who had suffered a CS were implanted with an ICM after a thorough screening process. The median time between the thromboembolic event and ICM implantation was 64 days [IQ range: 16–111]. All implanted patients were followed with remote monitoring until the first detected episode of AF or up to December 2018. Every remote monitoring transmission and related electrograms were analyzed by the dedicated Electrophysiology Nursing team and confirmed by experienced Electrophysiologists. AF was defined by any episode lasting greater than or equal to 2 minutes. Results During a median follow-up of 14.8 months [IQ range: 3.0–31.2], AF was detected in 65 out of 133 patients (48.9%). The median time from ICM implantation and AF detection was 3.5 months [IQ range: 0.9–6.7]. The prevalence of AF was 22.6%, 34.4%, 40.8% and 48.3% at 3, 6, 12 and 24 months respectively. At the multivariate analysis, high premature atrial contractions (PAC) burden and left atrium (LA) dilation were the only independent predictors of AF detection (HR 2.82, 95% CI 1.64–4.83, p&lt;0.001 for PAC; HR 1.75, 95% CI 1.03–2.97, p=0.038 for LA dimension). Patients were dived into categories based on the probability of AF detection (low, intermediate and high risk) and a new risk stratification algorithm was implemented (Figure 1). Conclusion After a thorough screening process, AF detection in patients with CS and ILM was quite high. Having a high PAC burden and LA dilation predicted AF episodes at the multivariate analysis. A new risk stratification algorithm was developed. Figure 1 Funding Acknowledgement Type of funding source: None