Impact of Chronic Oral H₂‐Antagonist Therapy on Left Ventricular Systolic Function and Exercise Capacity

It has been suggested that H₂-antagonists may adversely affect left ventricular systolic function. To assess the effects of cimetidine, famotidine, and ranitidine on exercise capacity and left ventricular systolic function, the authors conducted a randomized, double-blind, four-way crossover study in 15 healthy male volunteers with placebo control. Each subject underwent a maximal upright treadmill exercise test, aerobic metabolic assessment, and two-dimensional stress echocardiography on six separate occasions. The initial two treadmill exercise tests with aerobic metabolic assessment and stress echocardiography were performed to minimize the learning effect. In the final four evaluations, subjects were randomized to receive 7 days of oral treatment with cimetidine 400 mg twice daily, famotidine 40 mg daily, ranitidine 150 mg twice daily, and placebo. A comparison of exercise tests, aerobic metabolic assessment, and stress echocardiography results found no significant differences between any of the H₂-antagonists and placebo. In addition, there were no significant differences in test results between cimetidine, famotidine, and ranitidine. Specifically, exercise treadmill time, maximal oxygen consumption, respiratory quotient, maximal exercise systolic and diastolic blood pressure, maximal exercise heart rate, left ventricular end-diastolic dimension, left ventricular end-systolic dimension, and ejection fraction were not different between treatments. The authors conclude that 7 days of oral treatment with cimetidine, famotidine, or ranitidine has no deleterious effect on exercisecapacity or left ventricular systolic function in healthy subjects.