EFFECTS OF ANTIARRHYTHMIC DRUGS ON VARIABILITY OF VENTRICULAR RATE AND EXERCISE PERFORMANCE IN CHRONIC ATRIAL-FIBRILLATION COMPLICATED WITHVENTRICULAR ARRHYTHMIAS

For conversion of atrial fibrillation to sinus rhythm and management o f ventricular arrhythmias, antiarrhythmic drugs were frequently used. However, the effects of antiarrhythmic drugs on exercise performance a nd on the variability of ventricular rate were not available. This stu dy included 37 patients who had chronic atrial fibrillation complicate d with symptomatic ventricular arrhythmias. The patients were divided into three groups and received sotalol, propafenone, and procainamide, respectively. Before and after taking the drugs for 14 days, these pa tients received treadmill exercise test, 24 h Holter electrocardiogram , and tilt table test for evaluation of the exercise performance and t he variability of ventricular rate (including the mean RR intervals, m RR, the standard deviation of RR intervals, SDRR, and the root mean sq uare of the difference in successive RR intervals, rMSSD). All these a ntiarrhythmic drugs could suppress ventricular arrhythmia but only sot alol could significantly increase the exercise duration (374+/-50 to 4 76+/-55 s, P=0.02), and reduce the maximal heart rate (186+/-23 to 136 +/-16 beats/min, P=0.01) during exercise test. Furthermore, only sotal ol increased the mRR (777+/-60 to 885+/-66 ms, P=0.02), SDRR (190+/-40 to 216+/-48 ms, P=0.04) and rMSSD (223+/-48 to 253+/-40 ms, P=0.03) d uring 24 h Holter electrocardiogram. With head-up tilt, the mRR, SDRR and rMSSD all decreased significantly before drug therapy, and these c hanges were still present only after propafenone therapy. Therefore, c omparisons among sotalol, propafenone and procainamide showed that sot alol increased the exercise performance and the variability of ventric ular rate in patients who had chronic atrial fibrillation complicated with symptomatic ventricular arrhythmias. (C) 1998 Elsevier Science Ir eland Ltd.