Impaired Parasympathetic Activity and Prediction for Recurrence of Paroxysmal Atrial Fibrillation

초록

Background Alterations in autonomic nerve activity play an important role in the initiation and maintenance of paroxysmal atrial fibrillation (AF), and reduced vagal tone was associated with AF recurrence after electrical cardioversion. We investigated whether impaired parasympathetic activity might have been predictive impact on recurrence of paroxysmal AF. Methods Patients who had undergone symptomatic paroxysmal AF episode were enrolled. We studied consecutive patients with paroxysmal AF and age/sex-matched subjects served as a control group. Baseline examination was performed during status with sinus rhythm restored from AF. To assess autonomic nervous activity, we analyzed heart rate variability (HRV) through the 24 hours Holter monitoring, and exercise treadmill test (ETT) parameters, including heart rate recovery (HRR) and chronotropic incompetence. Results Among 114 of AF patients, 36 patients (32%) presented with AF recurrence (AR group), and another 78 patients maintained sinus rhythm (AN group). Comparing with healthy control, patients with AF had lower standard deviation of normal sinus to normal sinus intervals (SDNN) (125.79 ± 40.37 vs. 141.64 ± 33.72 ms; p=0.001). LF/HF ratio was higher in patients with AF than in the control group (1.23 ± 0.14 vs. 1.00 ± 0.54; p<0.001). Comparing between the AR group and the AN group, the components to high-frequency (HF) and the components of low-frequency (LF) were significantly lower in the AR group than in the AN group (p=0.040 and p=0.028). Maximal heart rate (HR) on the Holter monitor was higher in the AR group (150 ± 45 vs. 134 ± 32 beats per minute; p=0.028). Chronotropic incompetence did not showed difference among the groups, whereas impaired HRR showed relatively higher in the AR group (p=0.246 and p=0.072). Conclusion Our study suggested that impaired vagal tone with enhanced sympathetic activity have contributed to recurrence of paroxysmal AF.