Exercise testing in men with significant left main coronary disease.

The exercise tests of 26 male patients with significant left main disease were compared with those of 51 patients with three-vessel disease and 38 patients with two-vessel disease. Exercise-induced ischaemia (chest pain and/or greater than 1 mm ST segment change) occurred in 100 per cent of left main, 69 per cent of three-vessel, and 45 per cent of two-vessel disease patients. Though the mean peak work load was significantly higher in the two-vessel disease group than in those with three-vessel of left main disease, there was a wide overlap between groups. No intergroup differences were found in mean peak heart rates. In patients taking propranolol, no differences in mean peak work loads and heart rates were seen. The study showed that the absence of an exercise-induced abnormal electrocardiographic response virtually excludes left main disease. As judged by exercise performance, the presence of left main disease did not correlate with the severity of the patient's symptomatology. Propranolol did not influence the frequency of an ischaemic response in patients with left main or three-vessel disease.