Incidence and follow-up of Braunwald subgroups in unstable angina pectoris

Abstract

Objectives: This study was performed to establish the prognosis of patients with unstable angina within the subgroups of the Braunwald classification.

Background: Among many classifications of unstable angina, the Braunwald classification is frequently used. However, the incidence and risk for each subgroup in clinical practice have not been established.

Methods: Prospective data for 417 consecutive patients admitted for suspected unstable angina were analyzed. Patients were classified according to Braunwald criteria and followed up for 6 months. Survival, infarct-free survival and infarct-free survival without intervention are reported for each class.

Results: After in-hospital observation the final diagnosis was acute myocardial infarction in 26 patients (6%), noncoronary chest pain in 109 (26%) and definite unstable angina in 282 (68%). Recurrence of chest pain was significantly different for the different severity classes (28%, 45% and 64% for classes I [accelerated angina], II [subacute angina at rest] and III [acute angina at rest], respectively) but not for clinical circumstances (49% and 53% for classes B [primary unstable angina] and C [postinfarction unstable angina], respectively). Six-month and infarct-free survival (96% and 88%, respectively) were not significantly different between severity classes but were significantly different (p = 0.01) between classes B (97% and 89%) and C (89% and 80%). Infarct-free survival without intervention was best for class II (72%), intermediate for class I (53%) and worst for class III (35%). In multivariate analysis, elderly age, male gender, hypertension, class C and maximal (intravenous) therapy were independent predictors for death; elderly age and class C for infarct-free survival; and male gender, class III, class C, electrocardiographic changes and maximal therapy were associated with infarct-free survival without intervention.

Conclusions: Braunwald classification is an appropriate instrument to predict outcome. Risk stratification by these criteria provides a tool for patient selection in clinical trials and for evaluation of treatment strategies.