Abstract 17165: Natural History of Cardiac Function in Patients With Atrial Fibrillation Pre- and Post- Ablation

Intro: The natural history of cardiac function in atrial fibrillation (AF) patients undergoing pulmonary vein isolation (PVI) is incompletely described, as are heart rate patterns pre- and post-ablation. Goals: Examine autonomic status pre- and post-ablation using cardiac data (n=346) captured by implanted recorders Methods: Daily records (90-day pre to 365-day post ablation) were analyzed to extract parameters viz. heart rate variability (HRV), daytime heart rate (DHR) and nighttime heart rate (NHR). Analysis of variance was used to assess relationships between covariates (age, sex, etc.) and pre-post changes in parameters. We define "success" as patients who had no recurrence during post-ablation period per guidelines (“failed” otherwise). Results: Prior to ablation, mean DHR, NHR, and HRV were 69±10bpm, 60±9bpm, 122±32msec, respectively. After PVI, there was an immediate increase of ~5bpm in DHR (P<1e-4) and a more pronounced increase of ~11bpm in NHR (P<1e-4). HRV exhibited an immediate post-ablation peak decreasing by ~60msec (P<1e-4), with rapid recalibration over the first 10 post ablation days (increase of 20-25msec). Antiarrhythmic drug-use was a significant factor only in explaining changes in HRV (P=0.0126), while age was a significant factor only for the changes in DHR (P<1e-4). Comparing between subgroups, DHR and NHR were generally higher in the success than the failed group. At baseline, older patients (92 patients were of age>65years) had a significantly lower DHR and NHR than younger patients (117 were of age<56years). These age-based differences were amplified post ablation in DHR and NHR, but not HRV. Conclusions: PVI results in significant and sustained changes in heart rate parameters related to autonomic function. This relationship was observed globally, with the success group having significantly greater rises in DHR and NHR when compared to the failed group. Future work will explore whether these patterns exist in different cohorts.