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Four factors in the Braunwald classification for unstable angina as well as patient age and the coexistence of diabetes may independently predict the risk of major cardiac complications in patients with unstable angina. Braunwald's classification scheme is a scoring system for unstable angina that aids in diagnosis and patient management. Angina is chest pain. Researchers studied 393 patients with unstable angina who were admitted to coronary care units or intermediate care units. Twenty percent of these patients had major cardiac complications. Elements in the Braunwald classification that independently predicted the risk of major cardiac complications included having a heart attack within 14 days prior to admission, failure to receive a beta blocker or rate-lowering calcium channel blocker before admission, depression of the ST-segment on a baseline electrocardiogram, and the need for intravenous nitroglycerin on admission. Older patient age and the coexistence of diabetes were also significant predictors of major cardiac complications., Objectives. - To validate the Braunwald classification of unstable angina as a predictor of in-hospital cardiac complications; to determine which factors of the Braunwald classification contributed significantly to this prediction; and to devise a method of combining these predictive factors into an overall odds ratio for complications. Design. - A validation cohort of consecutive patients followed prospectively for in-hospital cardiac complications including myocardial infarction and death. Setting. - A community-based academic medical center. Patients. - A total of 393 patients admitted consecutively to the coronary care and intermediate care units with unstable angina. Main Outcome Measures. - Major cardiac complications including death, myocardial infarction, congestive heart failure, cardiogenic shock, and severe ventricular dysrhythmias. Results. - Multiple logistic regression analysis identified four clinical factors used in the Braunwald classification that predicted the in-hospital occurrence of major cardiac complications: (1) myocardial infarction within less than 14 days (odds ratio [OR], 5.72; 95% confidence interval [CI], 1.92 to 16.97); (2) need for intravenous nitroglycerin (OR, 2.33; 95% CI, 1.31 to 4.17); (3) lack of [beta]-blocker or calcium channel blocker prior to admission (OR, 3.83; 95% CI, 1.55 to 9.42); and (4) baseline ST depression (OR, 2.81; 95% CI, 1.45 to 5.47). Two other clinical factors, diabetes and age, were also significant predictors. Validation of this model using parametric and nonparametric bootstrap techniques revealed excellent agreement between the CIs for adjusted ORs derived from the multiple logistic regression and those derived from the bootstrap. Conclusions. - The classification of unstable angina proposed by Braunwald includes four factors that predict risk of major in-hospital cardiac complications. Specific factors used in this classification can be combined with diabetes and age to better stratify risk of major cardiac complications in this disorder using a simpler model. (JAMA. 1995;273:136-141)

The article discusses the relevance of percutaneous coronary intervention (PCI), which is performed in about 600,000 cases in the U.S. per year and costs a total of 12 billion U.S. dollars. In a study conducted by the authors to understand the need for the procedure, they use data from the National Cardiovascular Data Registry between July 1, 2009 and September 30, 2010 with an aim of finding the proportion of appropriate, uncertain or inappropriate PCI. They conclude that most PCIs done in the U.S. were appropriate with only 12% being tagged as inappropriate.