Short-term dynamics in fibrillatory wave characteristics at the onset of paroxysmal atrial fibrillation in humans.

INTRODUCTION

The purpose of this study was to investigate the magnitude and time course of fibrillatory wave dynamics during spontaneous onset of paroxysmal atrial fibrillation (AF).

METHODS

We studied fibrillatory waves in Holter recordings of paroxysmal AF with regard to the fibrillation-free interval (FFI) preceding each episode.

RESULTS

For 38 episodes of paroxysmal AF in 20 patients, dominant frequency (DF) ranged from 4.4 to 6.8 Hz (5.5 +/- 0.5 Hz). Long-FFI episodes showed a gradual increase in DF over the first 4 minutes (P < .0001). Short-FFI episodes showed an increase only from the first to the second minute (P < .003). For all 7 patients exhibiting both long-FFI and short-FFI episodes, short-FFI episodes had a higher initial DF (P < .002).

CONCLUSION

The dynamics during onset and their relation to the FFI are consistent with the influence of short-term electrophysiological changes and their reversal. These findings have implications for the timing of antifibrillatory interventions.