A square root pattern of changes in heart rate variability during the first year after circumferential pulmonary vein isolation for paroxysmal atrial fibrillation and their relation with long-term arrhythmia recurrence

BACKGROUND An incidental lesion of the parasympathetic ganglia during circumferential pulmonary vein isolation (CPVI) may affect heart rate variability (HRV). AIMS We studied the pattern of changes in HRV parameters and the relationship between the 1-year HRV change following CPVI and the recurrence of atrial fibrillation (AF). METHODS A total of 100 consecutive patients undergoing CPVI for paroxysmal AF were enrolled (mean [SD] age, 56 [11.2] years; 61 men). We measured HRV on the day before and after CPVI, and then at 1 month as well as 3, 6, and 12 months after CPVI using 24-hour Holter monitoring. RESULTS During the median follow-up of 33 months, 38 patients experienced the late recurrence of AF (LRAF). Compared with the pre-CPVI values, HRV was significantly attenuated on day 1 after CPVI in all patients. However, at 3 to 6 months after CPVI, all HRV parameters remained significantly decreased in LRAF-free patients but not in those with LRAF. The multivariate Cox analysis showed that earlyAF recurrence within the blanking period (hazard ratio [HR], 4.87; 95% CI, 2.44-9.69; P <0.001) and a change in the standard deviation of normal-to-normal intervals (SDNN) observed 3 months after ablation (HR, 0.99; 95% CI, 0.98-1; P= 0.01) were associated with LRAF. The cumulative LRAF freedom after CPVI was greater in patients with an SDNN reduction of more than 25 ms reported 3 months after ablation than in those with a reduction of 25 ms or lower (log-rank P= 0.004). CONCLUSIONS Sustained parasympathetic denervation during 12 months after CPVI was a marker of successful CPVI, whereas a 3-month post-CPVI SDNN reduction of 25 ms or lower predicted LRAF.