Long-term survival in patients with coronary artery disease: importance of peripheral vascular disease. The Coronary Artery Surgery Study (CASS) Investigators

Abstract

Objectives: The purpose of this study was to determine the importance of peripheral arterial disease in predicting long-term survival in patients with clinically evident coronary artery disease.

Background: Patients in the Coronary Artery Surgery Study (CASS) Registry were followed up for > 10 years.

Methods: Survival in 2,296 patients with peripheral arterial disease was compared with that of 13,953 patients without peripheral arterial disease using Kaplan-Meier survival curves. All patients had known stable coronary artery disease. Clinical, electrocardiographic (ECG), chest X-ray film and catheterization variables of the two groups were compared using the chi-square statistic or the two-sample t test. The independent effect of peripheral arterial disease (as well as other variables) on mortality was determined utilizing a Cox proportional hazards model.

Results: Patients with peripheral vascular disease were more likely to have hypertension, diabetes, family history of coronary artery disease, previous angina or myocardial infarction, previous coronary bypass surgery or to have smoked. They also had a higher incidence of congestive heart failure, ECG abnormality and modestly increased frequency of three-vessel disease. Independent correlates of long-term mortality for the entire cohort included age, smoking, diabetes, number of diseased coronary vessels, left ventricular function, hypertension, pulmonary disease, anginal class, previous myocardial infarction and peripheral vascular disease (all p < 0.001). At any point in time, patients with peripheral vascular disease had a 25% greater likelihood of mortality than patients without peripheral vascular disease (multivariate chi-square 25.83, hazard ratio 1.25, 95% confidence interval 1.15 to 1.36, p < 0.001).

Conclusions: Peripheral vascular disease is a strong, independent predictor of long-term mortality in patients with stable coronary artery disease. Aggressive attempts at secondary disease prevention are warranted in this high risk group.