4. Mathewson, F.A.L. and Varnam, G.S.: Abnormal electrocardiograms in apparently healthy people. Part I. Long term follow-up study. Circulation XXI (2); 196-203, February 1960.

Three thousand nine hundred and eighty three apparently healthly men had medical examinations and electrocardiograms reviewed at an average follow-up of 11.9 years. Thirty-two subject developed clinical myocardial disease, and seven deaths were attributed to heart disease. Of subjects that had electrocardiographic abnormalities at entry to the study, 3.3% developed clinical heart disease in contrast to 0.7 % whose initial electrocardiograms were normal. Certain electrocardiograms were judged to have only minor effect while changes in QRS voltage, T wave changes, RST changes were judged to be major determinants of later clinical heart disease.