[Quantitative evaluation of an antiarrhythmic therapy (disopyramide) in patients with frequent premature ventricular contractions (PVC) using a computer-assisted long-term ECG analysis system (author's transl)].

15 patients (pts.) - 12 males, 3 females - with frequent PVC (greater than 3%/16 hr during a qualifying period = LP) of different causes underwent after one-day placebo application (PL) drug treatment (disopyramide: loading dose 600 mg, 300 mg t.i.d.) over two days (D1, D2). The ambulatory continuously recorded long-term ECG was analysed using "Multipass-Scanning", a computer-supported analysis system for quantification of therapeutic success. The mean PVC rate of 17% prior treatment could be diminished in 87% of the pts. significantly. 5 pts. (group I) demonstrated a maximal PVC-reduction rate of more than 90 rel %. Among them in 2 pts. the PVC-rate did not exceed the 1%-level during D1 and D2 demonstrating an optimal therapeutic success. The max. PVC-reduction rate ranged between 80 and 90 rel % in 3 pts. (group II) and between 38 and 78 rel % in 5 pts. (group III). 2 pts. did not respond on DP. The mean DP-plasma level was higher in group-III pts. than in group-I or -II pts. in spite of a less therapeutic success. 7 pts. demonstrated a circadian behaviour of PVCs. Therefore the circadian variability increased. Also lower PVC rates under DP (D1, D2) led to an increase of spontaneous variability of PVCs. The maximal PVC depressant effect of DP appeared while the heart rate was 70 b.p.m. or higher. In conclusion, 87% of the pts. demonstrated a drug effect, but an effective antiarrhythmic therapy occurred only in 2 pts. (13%). A decrease of the frequency of rhythm disturbances led to a decrease of arrhythmia's variability and requires a prolongation of the ECG-recording time to eliminate the variabilities of arrhythmia occurred (spontaneous, circadian) and to avoid a mimicked therapeutic success.