Exercise-induced coronary artery spasm. A regional coronary blood flow study.

Regional myocardial blood flow during exercise was determined using the thermodilution technique in 2 patients suffering from both spontaneous and exertional chest pain. In both cases we observed that effort-related anginal attacks were due to coronary spasm with sudden reduction of regional left ventricular blood flow. In 1 patient the exercise-induced ST-segment elevation in the anterior leads was accompanied by a reduction of flow in the great cardiac vein. In the second patient the exercise-induced ST-segment depression in the lateral leads was accompanied by a reduction of coronary flow in the area supplied by the circumflex artery. In 1 patient, nifedipine was effective in prolonging exercise tolerance by preventing the occurrence of coronary spasm and by increasing blood supply to the ischemic region during exercise.