Adaptation to Exercise in Angina Pectoris

Twelve patients with angina pectoris manifested an ability to adapt to exercise during treadmill stress testing with electrocardiographic monitoring. Three patterns of adaptation were seen. Nine subjects had the ability to continue walking after the onset of angina with eventual disappearance or lessening of anginal pain and the associated ischemic ST-segment depression; anginal pain and ST depression began to diminish during a steady state of blood pressure and heart rate in those cases in which these factors were measured. Four subjects were able to continue walking for long periods of time during a state of angina and ischemic ST depression. Three subjects demonstrated an increase in exercise capacity after being warmed up by a preceding bout of exercise-induced angina; blood pressures and heart rates during the initial, "warming-up" effort tended to be higher than those during the early stages of the second effort. In three subjects more than one of these patterns of adaptation were demonstrated. Five of the subjects showed striking subjective and objective improvement in exercise tolerance while on a program of regular walking exercise. Selective coronary cineangiography was performed in eight of these patients and two patterns of coronary disease were seen: (1) occlusion of a major coronary vessel with good collateral channels circumventing the obstruction; (2) strategically placed, proximal, stenotic lesions in major coronary vessels without frank occlusion and without discernible collateral development. Some diagnostic and therapeutic implications of these findings are discussed.