The electrocardiogram in obesity: statistical analysis of 1,029 patients.

The electrocardiogram in 1,029 obese subjects was correlated with the severity of obesity and with age, sex and blood pressure. The heart rate, PR interval, QRS duration, QTc interval and voltage (R + S or Q wave in leads I, II and III) increased, and the QRS vector shifted to the left with increasing obesity. These changes were independent of age, sex and blood pressure. Bradycardia was present in 19% of the patients, but tachycardia in only 0.5%. ST and T wave abnormalities were present in 11%, correlating better with increasing age and blood pressure than with severity of obesity. Conduction abnormalities were infrequent. Low voltage was present in only 3.9% of the patients and QTc prolongation was present in 28.3%. The heart rate and QRS voltage increase with increasing obesity. Conduction is slowed, and the QRS vector shifts toward the left as percent overweight increases. These changes must be considered when evaluating both baseline electrocardiographic studies in obese patients and the changes seen during weight reduction.