[Spontaneous variations in the characteristics of ventricular extrasystole]

The authors studied 65 patients (mainly with chronic coronary heart disease) with 48 hours of continuous two-channel Holter recordings of antiarrhythmic drugs. Spontaneous qualitative day to day variations in ventricular premature beats (VPB) exceeding 50% were recorded in 22 (33.8%) cases, those exceeding 75%--in 10 (15.4%) cases. Additional cases of severe Lown grade VPB during the second day of monitoring were revealed in 8 (12.3%) cases. We conclude, that marked day to day variation in VPB require a strict criterion (greater than 75% decrease) to define antiarrhythmic drug efficacy.