RESUMEN
Purpose - To assess the presence and the prevalence of arrhythmias and the variability of the heart rate in the medium-term postoperative period following the maze procedure for chronic atrial fibrillation (AF). Methods - Seventeen patients with a mean age of 51.7+12.9 years, who previously underwent the maze procedure without cryoablation for chronic atrial fibrillation, were evaluated with the 24 hour electrocardiogram (ECG) - Holter monitoring from the 6th month after the operation. Valvular and coronary procedures were concomitantly performed. Results - The mean heart rate during Holter monitoring was 82+8bpm; the maximal heart rate was 126+23 bpm and the minimal heart rate 57+7 bpm. Sinus rhythm was found in 10 (59 per cent) patients and atrial rhythm was found in 7 (41 per cent). Supraventricular extrasystoles had a rate of 2.3+5.5 per cent of the total number of heartbeats and occurred in 16 (94 per cent) patients. Six (35 per cent) patients showed nonsustained atrial tachycardia. Ventricular extrasystoles, with a rate of 0.8+0.5 per cent of the total heart-beast, occurred in 14 (82 per cent) patients. The chronotropic competence was normal in 9 (53 per cent) patients and attenuated in 8 (47 per cent). The atrioventricular conduction (AV) was unchanged in 13 (76 per cent) patients and there were 4 (24 per cent) cases of first degree atrioventricular block (AVB). Conclusion - After maze procedure, the values for the mean heart rrate, AV conduction and chronotropic competence approach the normal range, although some cases show attenuation of the chronotropic responce, first degree AV block or benign arrhythmias.