CLINICAL-STUDY ON COUPLING INTERVAL OF VENTRICULAR PREMATURE CONTRACTION IN PATIENTS WITH ORGANIC HEART-DISEASE

The characteristics of the coupling interval (CI) of ventricular premature contraction ( VPC) were studied in 100 patients with frequent VPCs using 24h ambulatory ECG recording. All R-R intervals were registered on computer to determine the mean value of CIs (Mean CI) and the standard deviation of CIs (SD-CI). We compared the Mean CI and the SD-CI between idiopathic VPCs and VPCs with organic heart disease (OHD). In addition, we evaluated the efficacy of disopyramide (DP) and mexiletine (MX) and we examined the relationship between the efficacy of these drugs and the characteristics of CI. The Mean CI of VPCs with OHD was longer than that of idiopathic VPCs (530 vs. 494 msec, p < 0. 05). The SD-CI of VPCs with OHD was larger than that of idiopathic VPCs (54.1 vs. 39.3 msec, p < 0.01). In all treated cases, the drug efficacy was not different between DP (11/18, 61%) and MX (9/19, 47%). However when we isolated cases of OHD, we found a tendency that DP (9/12, 75%) was more effective than MX (7/16, 44%). In cases where DP was administered, the Mean CI of VPCs was not different between effective and ineffective cases, while in cases where MX was administered, the Mean CI of ineffective cases had a tendency to be longer than that of effective cases (552 vs. 506 msec, p < 0.1). In cases where DP was administered, the SD-CI of VPCs showed no difference between effective and ineffective cases, while in cases where MX was administered, the SD-CI of ineffective cases was larger than that of effective cases (66.9 vs 36.7 msec, p < 0.05). These results suggest that DP seems to be superior to MX for VPCs with OHD, because of the fact that MX was not effective on VPCs with OHD in which the Mean CI was longer and the SD-CI was larger.