Autonomic modulation of the sinus node following electrical cardioversion of persistent atrial fibrillation: relation with early recurrence.

BACKGROUND: The aim of this study was to correlate early atrial fibrillation (AF) relapses with heart rate variability (HRV) parameters immediately recorded after electrical cardioversion (EC) of persistent AF. METHODS AND
RESULTS: We performed the spectral analysis of short-term HRV 30 min after EC in 25 patients with persistent AF. The numbers of patients who maintained sinus rhythm at 48 h, 7, and 30 days were 22, 16, and 14, respectively. A very low low frequency/high frequency ratio (0.93+/-0.08 vs. 1.89+/-1.30; p<0.003) significantly identified patients with AF recurrence at 48 h in comparison to patients without AF recurrence. On the contrary, HRV parameters did not identify patients with AF recurrence at 7 or 30 days.
CONCLUSIONS: AF relapsed within the first 48 h more frequently in patients who presented a predominant vagal tone immediately after the restoration of sinus rhythm.