High Amplitude R-Waves in Japanese and American Telephone Executives

Executives between the ages of 35 and 58 in the top six levels of the Tokyo office of the Nippon Telegraph and Telephone Public Corporation and the New York office of the American Telephone and Telegraph Company were examined as part of an international comparison of cardiovascular risk factors. Included in the standardized examinations were smoking histories, 12-lead electrocardiograms, and measurements of skin folds, blood pressure, pulse rates before and after exercise, heart size, serum cholesterol and serum triglycerides. Among the 826 Japanese subjects, 14.5 per cent had R-waves classified as high (3–1 according to the Minnesota code) and 8.2 per cent as slightly high (code 3–3). The prevalence of these findings was much lower among the 959 Americans, namely 4.5 per cent coded 3–1 and 1.8 per cent coded 3–3. Comparisons between national groups suggested slight associations of high R-waves with decreased subcutaneous fat and increased blood pressure. Within national groups, however, these associations were not consistent. Only among the Americans was there an association of high R-waves with subcutaneous fatness, and only among the Japanese was there an association with increased blood pressure. The associations with smoking and heart size were trifling, and there was no association of high R-waves with pulse rates or with elevated serum lipids.