Prospective validity of measuring angina severity with Canadian Cardiovascular Society class: The ACRE study.

BACKGROUND: Although the prevalence of angina remains high, the importance of grading angina severity is unclear.
OBJECTIVES: To determine the extent to which angina severity is associated with angiographic findings, and the rate of revascularization, mortality and nonfatal myocardial infarction.
METHODS: Prospective, population-based study with a 2.5-year follow-up of 2849 consecutive patients with angina undergoing coronary angiography at Barts and the London NHS Trust, London, United Kingdom, in the Appropriateness of Coronary Revascularisation (ACRE) study. Angina severity was assessed with the Canadian Cardiovascular Society (CCS) classification, ranging from class I (mild) to IV (severe). Outcome measures were revascularization rates, and all-cause mortality and nonfatal myocardial infarction.
RESULTS: In age-adjusted analyses, a higher CCS class was linearly associated (P<0.001) with a higher number of diseased vessels and impaired left ventricular function. When adjusting for age, sex, smoking, history of hypertension, diabetes, number of diseased vessels, left ventricular function, use of acetylsalicylic acid, beta-blockers or statins, and revascularization status (for death and nonfatal myocardial infarction), a higher CCS class was linearly associated with higher coronary angioplasty (P<0.001) and bypass graft (P=0.03) rates, and lower all-cause mortality and nonfatal myocardial infarction (P<0.001; CCS IV versus I: hazard ratio 2.44, 95% CI 1.46 to 4.09).
CONCLUSION: CCS class was linearly associated with angiographic findings, revascularization rates, mortality and nonfatal myocardial infarction. These findings support the importance of a four-level grading of symptom severity among angina patients.