Significance of site of origin of premature ventricular contractions

One hundred and sixty-five inpatients with premature ventricular contractions (PVC's) were clinically evaluated in regard to the presence (130 patients) or absence (35 patients) of organic heart disease. PVC's were classified based on QRS morphology (bundle branch block pattern) in Lead V₁ as being either left ventricular (66 patients), right ventricular (71 patients), or of both ventricles (28 patients). The incidence of organic heart disease was significantly greater in patients with left ventricualr PVC's 60 of 66 (91 per cent) and biventricular PVC's 25 of 28 (89 per cent) than in patients with right ventricular PVC's 45 of 71 (63 per cent) (p < 0.001). Of the 130 patients with organic heart disease, 60 (46 per cent) had left ventricular PVC's, 25 (19 per cent) had biventricular PVC's, and 45 (35 per cent) had right ventricular PVC's. of the 35 patients without organic heart disease, six (17 per cent) had left ventricualr PVC's, four (9 per cent) had biventricular PVC's, and 26 (74 per cent) had right ventricular PVC's. These data suggest the following conclusions regarding inpatients with PVC's: (1) Organic heart disease is frequent in patients with right ventricular PVC's and almost universally present in patients with left ventricular and biventricular PVC's. (2) Patients without organic heart disease primarily have PVC's of right ventricular origin. The mechanism of the latter association is unknown.