We report clinical experience with the coronary vasodilator nifedipine in 127 patients with symptoms of myocardial ischemia associated with electrocardiographic or angiographic evidence, or both, of coronary-artery spasm. In the majority of patients conventional antianginal therapy including nitrates and beta-adrenergic blockers failed, and in one third of the patients at least one episode of ventricular tachycardia developed during an attack of angina. Nifedipine (40 to 160 mg every 24 hours) significantly reduced the mean weekly rate of anginal attacks from 16 to two (P less than 0.001). Similar marked reductions in the nitroglycerin requirement were noted. In 63 per cent of the patients complete control of anginal attacks was achieved, and in 87 per cent the frequency of angina was reduced by at least 50 per cent. Nifedipine was generally well tolerated, with only 5 per cent of the patients requiring termination of the drug because of intolerable side effects. This experience with nifedipine suggests that it is a highly effective drug for the treatment of coronary-artery spasm and variant angina.

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In ten healthy, asymptomatic men, intra-arterial pressure and electrocardiograms were recorded during various types of exercise. Potential subendocardial blood flow was estimated from a diastolic pressure time index (DPTI) and myocardial oxygen requirements estimated from the tension time index (TTI). The ratio DPTI/TTI provided an estimate of the supply/demand relationship With sudden vigorous exercise without warm-up, the DPTI/TTI was below 0.35 in three men who had ischemic electrocardiograms, below 0.44 in three men with minor ST abnormalities, and above 0.44 in four men with normal ST segments. With a prior warm-up exercise, sudden exercise caused no ischemic changes, but DPTI/TTI was below 0.44 in two subjects who had minor ST abnormalities. Maximum treadmill testing produced higher heart rates and TTI than did sudden exercise, but DPTI/TTI was above 0.44 in all cases and no ST abnormalities occurred. Abnormal electrocardiographic responses produced by sudden, vigorous exercise in normal men may represent subendocardial ischemia caused by a transient, unfavorable alteration in the subendocardial oxygen supply/demand relationship which is predictable from arterial pressure measurements.

Twenty patients with Prinzmetal's variant of angina are described and the literature on the subject is reviewed. This syndrome is characterized by anginal attacks at rest with S-T segment elevation, while exercise capacity is well preserved. Coronary arteriography usually demonstrates significant, focal, obstuctive disease of the major coronary artery predicted from the distribution of S-T elevation seen in the ECG during attacks. Occasionally the coronary disease is minimal or absent. The cause of attacks is believed to be transient, spastic occlusion of a major coronary artery, which was actually observed during surgery in one case. Because of this unusual pathophysiology, these patients may not make ideal candidates for isolated saphenous vein bypass surgery. Other diagnostic, therapeutic, and prognostic implications of this interesting anginal syndrome are discussed.