Unstable angina pectoris of new onset: a prospective clinical and arteriographic study of 75 patients.

Seventy-five patients with unstable angina pectoris of new onset (defined as of less than 90 days' duration) were prospectively evaluated in terms of clinical and arteriographic findings. In all patients the angina was considered unstable in terms of ease of provocation of anginal attacks and frequency of occurrence of attacks. Sixty patients had significant obstruction of at least one coronary artery, whereas 15 had insignificant disease (less than 70 percent arterial narrowing) or normal coronary arteries. Thirty-one patients (52 percent) had single vessel coronary disease, 11 (18 percent) had double vessel disease and 9 (15 percent) had triple vessel disease; the remaining 9 (15 percent) had left main coronary artery disease, either alone or in association with other vessel involvement. Of the 31 patients with single vessel disease, 24 (77 percent) had stenosis of the left anterior descending artery. The patients with single vessel disease did not differ from the patients with multivessel involvement with respect to risk factors or clinical presentation. It is concluded that patients with unstable angina of new onset have an unusually large incidence of single vessel coronary artery disease predominantly involving the left anterior descending coronary artery. Thus, these patients constitute a unique subset of patients with angina pectoris.