Prolonged PR interval and coronary artery disease.

Of 2744 patients seen in clinic practice, 37 were found to have a prolonged PR interval. The causes of prolongation of the PR interval were: congenital heart disease, 6; chronic rheumatic heart disease, 2; digitalis induced, 4; miscellaneous, 5; and coronary heart disease, 20. Of the 20 associated with coronary heart disease, 8 (2I.6% of all the patients with prolonged PR interval) had myocardial infarction while I2 (3244% of all the patients with prolongedPR interval) had angina pectoris. In those who had infarction, the location of the infarct was dominantly inferior. The diagnostic possibilities of a prolonged PR interval can be inferredfrom the high incidence of association with coronary heart disease. Thirty-two per cent of the total cases with prolongation of the PR interval in this study were due to coronary heart disease with angina, and of I93 cases of angina about 6-2 per cent had prolongation of the PR interval.