Appropriateness of diagnosis of unstable angina pectoris in patients referred for coronary arteriography

Background: A diagnosis of unstable angina pectoris (UAP) often carries with it a decision to catheterize the patient promptly. However, UAP remains a clinical diagnosis, based mostly on a patient's clinical history and electrocardiogram (ECG) findings. Objective: To evaluate whether the diagnosis of UAP is overused in patients referred for coronary arteriography. Methods: Ninety-six patients with a diagnosis of UAP who were referred for invasive studies were re-examined clinically before catheterization. Coronarography was independently reviewed for correlation with clinical findings. Results: Based on the patient's history and ECG changes, UAP was classified by two independent cardiologists as 'very likely' in 58% and 49%, 'possible'in 19% and 30%, and of 'low probability' in 23% and 21%, respectively. Patients with 'very likely' UAP had a high incidence of significant coronary lesions (87% and 96% for each cardiologist) and complex lesions by angiography (41% and 49%, respectively). Patients with a diagnosis of 'low probability' UAP had a low incidence of significant coronary lesions (55% for each cardiologist) and a very low incidence of complex angiographic lesions (5% for each cardiologist). Patients with 'possible' UAP had intermediate results. Conclusion: Because of a presumptive diagnosis of UAP, approximately 22% of all patients referred for coronarography have no clinical andTor ECG evidence for this diagnosis. The incidence of complex coronary lesions in this group is very low.