Effect of Marihuana and Placebo-Marihuana Smoking on Angina Pectoris

Abstract

We evaluated the effect of smoking marihuana versus placebo marihuana on cardiovascular function and on exercise-induced angina in 10 patients with angina pectoris. With the subject resting smoking one marihuana cigarette increased the product of systolic blood pressure times heart rate and venous carboxyhemoglobin level and decreased the exercise time until angina 48 per cent. Smoking one placebo marihuana cigarette increased the venous carboxyhemoglobin level, did not affect the product of systolic blood pressure times heart rate of resting subjects, and decreased the exercise time until angina 8.6 per cent. Smoking marihuana significantly decreased the exercise time until angina more than smoking placebo marihuana (p<0.001). Smoking marihuana probably increases the myocardial oxygen demand and decreases myocardial oxygen delivery, causing patients with angina to experience agina after exercise sooner, and with less work, (N Engl J Med 291:65–67, 1974)