Exercise-induced coronary spasm is occasionally recognized in patients with variant angina, but the patterns of exercise-induced coronary spasm and its relation to clinical features are still not clear.

Eight consecutive patients with variant angina without significant stenosis of the coronary artery performed serial treadmill exercise tests during early morning, late morning, and in the afternoon. The subjects repeated the tests after administration of atropine and doxazosin or phentolamine.

(Upon drug administration), anginal episodes with ST-segment changes (elevation 5, depression 1) Occurred repeatedly in 6 of the 8 patients during early morning; the episodes occurred in only 2 patients during the afternoon exercise test. Four patients showed exercise-induced angina and ST-segment changes during early morning but not in the afternoon, and 2 of them showed mild episodes of exercise-induced angina and ST-segment changes during late morning. Three of the four patients had the characteristic clinical history of angina in early morning during usual activities but not during daytime activities despite the activities being more strenuous. Another 2 patients showed both exercise-induced ST-segment elevation and angina in early morning and afternoon, and they had the characteristic history of more episodes at night and in early morning but only occasionally in the daytime with or without relation to activity. One of the two patients showed intermittent ST-segment elevation during the exercise test. The other two patients had exercise-induced episodes neither in the early morning nor in the afternoon; they had a characteristic history of episodes only at night during sleep but never in the early morning nor in the daytime. Atropine did not suppress the exercise-induced angina in 4 of 5 patients studied. Doxazosin or phentolamine suppressed the exercise-induced episodes in 3 of 5 patients studied but aggravated spontaneous episodes in 3 patients.

These data suggest that there's possibility of presence of different patterns of exercise-induced coronary spasm, which may be induced by different mechanisms from those in spontaneous episodes in patients with variant angina.