SUMMARY To define the prevalence, frequency and characteristics of premature ventricular complexes (PVCs) in adults free of recognizable heart disease, we performed 24-hour ambulatory electrocardiography on 101 subjects (51 men and 50 women, mean age 48.8 years) in whom physical examination, chest x-ray, ECG, echocardiogram, maximal exercise stress test, right-and left-heart catheterization and coronary arteriography were normal. Thirty-nine subjects had at least 1 PVC/24 hours, but only four had more than 100 PVCs/24 hours and fewer than five had more than five PVCs in any given hour. The probability of having at least 1 PVC/24 hours increased with age (chi square = 11.789, p = 0.019). The number of PVCs/24 hours was also positively associated with age (r -0.33, p = 0.001). There was no consistent relationship between the presence or number of PVCs/24 hours and sex, blood pressure, weight, height, body mass index, serum potassium or calcium, cholesterol and triglyceride, hemoglobin, the ingestion of coffee, tea or alcohol, and cigarette smoking. Four subjects had multiform PVCs, two of whom had early PVCs.

In order to study the effect of age, blood pressure and gender on premature ventricular contractions (PVCs), 24-hour ambulatory electrocardiography was performed on 338 apparently normal subjects (Group I; 209 men, 129 women, age 17 to 69, mean 48.5 +/- 11.7) and on 100 subjects with normal hearts proven by extensive invasive and noninvasive testing (Group II; 51 men, 49 women, age 16 to 68, mean 48.8 +/- 10.2). Apparently normal subjects (Group I) had a higher prevalence of PVCs (61.8% vs. 39.0%, p less than 0.001) and of complexity (16.3% vs. 4.0%, p less than 0.003) than subjects with normal hearts (Group II). The distribution of subjects according to PVC frequency was bimodal in Group I and unimodal in Group II. PVC prevalence increased with age in both the apparently normal group (p less than 0.001), and in the group with normal hearts (p less than 0.025). On the contrary, apparently normal (Group I) men had almost twice the PVC prevalence (74.6% vs. 41.1%, p less than 0.001) and complexity (20.1% vs. 10.1%, p less than 0.25) than apparently normal women, while gender had no effect on PVC prevalence in subjects with normal hearts (Group II). Systolic blood pressure was also associated with PVC prevalence (p less than 0.001) and complexity (p less than 0.02) in apparently normal subjects (Group I) but not in subjects with normal hearts (Group II). These data indicate: that apparently normal subjects have higher prevalence of PVCs and of PVC complexity than subjects with normal hearts, probably because of undetected cardiac disease; that the increase in PVC prevalence with age is not necessarily due to cardiac disease; and that PVC complexity in apparently normal subjects should raise the suspicion of cardiac disease especially in men, in subjects with hypertension and in the older age group.