Comparative effect of nadolol and propranolol on exercise tolerance in patients with angina pectoris.

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Abstract
The effect of nadolol, a new long-acting .beta.-adrenergic blocking drug, on exercise tolerance was compared with propranolol in a randomized, double-blind crossover study involving 14 patients with angina pectoris caused by coronary artery disease. Exercise tolerance was evaluated by graded upright exercise testing to symptom-tolerated maximal exercise. Cardiac function was evaluated by sequential phonocardiograms, echocardiograms and chest X-rays synchronized to end-diastole. At the same daily dose, both drugs decreased consumption of glyceryl trinitrate to an equal extent (P < 0.02) but nadolol 240 mg a day reduced episodes of angina pectoris more significantly than the same amount of propranolol (P < 0.05). Both drugs resulted in similar improvements in exercise tolerance (30%, P < 0.01), and external work performed (48%, P < 0.01). A slightly greater suppression of the heart rate during exercise was observed with nadolol than with propranolol (P < 0.05). Though both drugs caused a significant decrease in the resting heart rate, the rate corrected systolic time intervals changed very little from control. The effects of the 2 drugs could not be differentiated by echocardiography or phonocardiography. Cardiac end-diastolic volume measured from a chest X-ray film was increased during treatment with both nadolol (15%, P < 0.01) and propranolol therapy (11%, P < 0.001), but a slightly greater transverse cardiac diameter (P < 0.02) and cardiothoracic ratio (4%, P < 0.001) was associated with nadolol. Nadolol was as effective as propranolol in relieving symptoms and improving exercise tolerance in patients with angina pectoris. The effect of the drugs was best evaluated by the suppression of the exercising heart rate. Nadolol appears to be slightly more potent than propranolol and has the advantage of a more convenient dosage schedule, but has a similar myocardial depressant effect.