Angiographic and prognostic correlates of cardiac output by cardiopulmonary exercise testing in patients with anterior myocardial infarction

Study objective: To assess the diagnostic and prognostic value of cardiac output assessed by cardiopulmonary exercise testing in patients with anterior acute myocardial infarction (AMI) and left ventricular dysfunction. Patients and setting: Forty-six patients with AMI (7 female patients; mean +/- SD age, 55 +/- 8 years; ejection fraction, 39 +/- 7%) underwent cardiopulmonary exercise testing and coronary angiography following hospital discharge. Measurement and results: Cardiac output was estimated from oxygen uptake ((V) over dotO(2),) during exercise according to a method based on the linear regression between arteriovenous oxygen content difference and percent maximum (V) over dotO(2). Angiograms were scored using Gensini and Duke "jeopardy" scores. Cardiac output at anaerobic threshold (COAT) less than or equal to 7.3 L/min was the best cutoff value for identifying multivessel coronary artery disease (relative risk, 3.1). Angiographic scores were significantly higher in patients with COAT < 7.3 L/min as compared to those with COAT > 7.3 L/min (82 +/- 8 vs 53 +/- 7 and 6 +/- 2 vs 4 +/- 3, respectively; p < 0.05) and were inversely and significantly correlated to COAT. Conversely, no correlation was found with ECG changes. COAT, (V) over dotO(2) at anaerobic threshold, and peak (V) over dotO(2) were univariate prognostic indicators. However, using Cox's model, COAT was the only multivariate predictor of outcome (odds ratio, 0.28; 95% confidence interval [CI], 0.09 to 0.9). Moreover, COAT < 7.3 L/min was associated to an increased risk of further cardiac events (odds ratio, 5; 95% CI, 1.4 to 17) and provided a significant discrimination of survival for the combined end point of cardiac death, reinfarction, and clinically driven revascularization. Conclusions: COAT is a safe and feasible tool providing additional diagnostic and prognostic information in patients with AMI.