The response to drug therapy in unstable angina on the basis of coronary angiography findings.

Among 366 unstable angina pectoris patients at our hospital, myocardial infarction was common (15.7%) in those with attacks of chest pain lasting for at least 20 min. There was also a high incidence (30.3%) when chest pain continued after the start of inpatient treatment. To investigate the etiology of unstable angina, coronary arteriography was performed in both the unstable and stable stages in these patients and the results were compared. The role of coronary spasm and coronary thrombosis in unstable angina was investigated, and the efficacy of continuous infusion of either diltiazem or isosorbide dinitrate as treatment for these patients was compared. Coronary arteriography in the unstable stage showed, no clear differences in the morphology of the stenotic site and the degree of stenosis between the patients with and without infarcts when urokinase or isosorbide dinitrate were injected into the coronary arteries. When drug treatment was effective, the angina was stabilized without any improvement in the degree of stenosis or the morphology of the involved coronary vessel. Thus, it was difficult to predict the response to treatment from coronary arteriography performed in the unstable stage. Diltiazem was more effective than isosorbide dinitrate, and it appears that some action other than coronary dilatation was involved in achieving the remission of unstable angina.