Fourier Transformation Analysis of Atrial Fibrillation Intervals Following Ibutilide and Procainamide to Predict Successful Cardioversion

The frequency and the degree of fractionation of intraatrial recordings during atrial fibrillation (AF) have a correlation with the wavelengths and the size of the reentry pathways. We hypothesized that spectral ana lysis might help to explain the mechanism of antiarrhythmic drug- induced termination of AF. The frequency spectrum of monophas ic action potenti als recorded in the right atrium was ana lysed us ing Fast Fourier Transformatian (FFT). The maximal, minimal, first 5 peak frequencies and the width of frequency distribution within each 5 see segments were calculated before and after placebo (group C, n=7), ibut il ide 1.6±0.4 mg (group I, n= IO) or procainamide 1240±221 mg (group P, n= 10) infusion in 24 patients with AF. Age (66±9, 68±6 and 64±7), LA size (40±8, 44±5 and 46±4 mm) and LV EF (44± 11 , 43±7 and 40±11) were s imilar in group I, P and C, respectively (p>0.05). Ibutilide and procainamide decreased the peak AF frequency from 6.2±0.6 and 6.5±1.1 Hz to 4.3±0.3 and 4.5±0.8 Hz, respectively (p<0.00 1), whereas placebo had no effect on FFT. Ibutilide decreased the frequency of the peaks significantly within 30 see after each dose. In 3 patients in group I, AF terminated. Cardioverted patients tented to have a lower frequency at baseline than nonconverters (5.7±.3 vs. 6.4±.6 Hz). Ibutilide decreased the frequency of AF to 3.5±0.1 Hz before cardioversion.
CONCLUSIONS
Fourier transformatian analysis of AF electrograms is a useful method for evaluation of the effect of drugs on atrial tissue. Ibutilide may decrease the frequency of AF to a critica! level before cardioversion.