Spectral characteristics of human atrial fibrillation waves of the right atrial free wall with respect to the duration of atrial fibrillation and effect of class I antiarrhythmic drugs

The aim of this study was to use fast Fourier transform analysis to clarify the characteristics of human atrial fibrillation (AF) waves with respect t o the duration of AF and the effect of class I antiarrhythmic drugs. Twenty two patients (10 paroxysmal AF, 12 persistent AF) without organic heart di sease were studied by conventional electrophysiological methods. Electrogra ms were recorded from the fight atrial free wall during AF and spectral ana lysis was performed for 35s (16 consecutive 4096-ms epochs with 50% overlap ) and the fibrillation cycle length (FCL) was calculated from the peak freq uency. Mean FCL and SD were determined from 16-epoch data, and the temporal variability of FCL was defined as the SD of FCL. Paroxysmal A-F had a long er mean FCL than persistent AF (178 +/- 26ms vs 139 +/- 16ms, p <0.001) and AF duration had a significant inverse correlation with mean FCL (r=-0.79, p <0.001). The temporal variability of FCL was significantly greater in par oxysmal AF than in persistent AF (p <0.05) and there was a significant posi tive correlation between the mean FCL and the temporal variability of FCL ( r=0.66, p <0.001). In 8 of 18 patients given a class I antiarrhythmic drug (cibenzoline or procainamide), AF was terminated and in those patients the mean FCLs before administration of class I drugs were significantly greater than in patients without AF termination. With respect to mean FCL before d rug administration, conversion occurred in 100% of patients with FCL greate r than or equal to 168 ms and in 17% of those with FCL < 168 ms. A longer d uration of AF shortens the mean FCL, which is consistent with atrial electr ical remodeling. Class I drugs prolong the mean FCL above a critical level and will terminate AF, which can be estimated from the mean FCL before drug administration.