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* From the Cardiovascular Research Foundation (Drs. Bigi, Desideri, and Cortigiani), "S. Giacomo" Hospital, Castelfranco Veneto, Italy; and Division of Cardiology (Drs. Rambaldi and Sponzilli), "S. Paolo" Hospital; The Institute of Biomedical Sciences (Dr. Fiorentini), University of Milan, Milan, Italy.
Correspondence to: Riccardo Bigi, MD, via Visoli, 1, 23037 Tirano (SO), Italy; e-mail: rbigi{at}tiscalinet.it
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
(
O2) during exercise according to a
method based on the linear regression between arteriovenous oxygen
content difference and percent maximum
O2. Angiograms were scored using Gensini
and Duke "jeopardy" scores. Cardiac output at anaerobic threshold
(COAT)
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,
O2 at anaerobic threshold, and peak
O2 were univariate prognostic
indicators. However, using Coxs 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.
Key Words: acute myocardial infarction cardiac output cardiopulmonary stress testing
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