Electrocardiographic abnormalities in apparently healthy men and the risk of sudden death.

Identification of individuals at increased risk of sudden cardiac death is an important but difficult problem, especially in persons without clinically apparent heart disease. The ability of the electrocardiogram (ECG) to predict sudden death was determined in a study of 3983 men who were 30.8 years of age (mean) at entry and who had been followed with regular examinations, including ECGs. During the 30-year observation period, 70 cases of sudden death occurred in men without previous clinical manifestations of heart disease. Electrocardiographic abnormalities were detected before sudden death in 71.4% of cases. The abnormalities were, in decreasing order of frequency, ST segment and T-wave abnormalities, ventricular extrasystoles, left ventricular hypertrophy, complete left bundle branch block, and pronounced left axis deviation. When these electrocardiographic findings in men without clinical manifestations of heart disease were related prospectively to the incidence of sudden death, ST segment and T-wave abnormalities, ventricular extra-systoles, left ventricular hypertrophy and complete left bundle branch block were significant predictors of sudden death, while left axis deviation and right bundle branch block were not significant predictors of sudden death. Increased severity of primary T-wave abnormalities and the association of ST segment and T-wave abnormalities with increased QRS voltage further increased the sudden death risk. The combination of ventricular extrasystoles with either ST-T abnormalities or left ventricular hypertrophy considerably increased the risk of sudden death. Thus, these data indicate that electrocardiographic abnormalities detected on routine examination in men without clinical evidence of heart disease identify men at an increased risk of sudden death.