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Original Articles |
From the Division of Cardiology (S.J.S.), Department of Medicine, Northwestern University Feinberg School of Medicine; and the Section of Cardiology (T.T., S.R., J.S., S.L.A., M.G.), Department of Medicine, University of Chicago, Chicago, Ill.
Correspondence to Mardi Gomberg-Maitland, MD, MSc, Director of Pulmonary Hypertension, University of Chicago Medical Center, 5841 S Maryland Ave, MC 2016, Chicago, IL 60637. E-mail mgomberg{at}medicine.bsd.uchicago.edu
Received July 16, 2008; accepted March 30, 2009.
Background— The ability of the Naughton-Balke exercise treadmill test, an objective indicator of exercise capacity, to predict abnormal hemodynamics and mortality in pulmonary hypertension is unknown.
Methods and Results— We performed a cohort study of 603 patients with pulmonary hypertension from 1982 to 2006, and studied the utility of exercise treadmill test as a predictor of abnormal hemodynamics and death. We used multivariable linear regression to determine whether exercise capacity, measured in metabolic equivalents, was associated with abnormal hemodynamics, and we used a Cox proportional hazards model to determine whether decreased exercise capacity predicted death. Mean age was 50±15 years, 76% were women, 63% had World Health Organization category I pulmonary arterial hypertension, and 23% were World Health Organization functional classes I and II. Mean exercise capacity was 3.7±2.2 metabolic equivalents. Decreased exercise capacity was independently associated with elevated right atrial and mean pulmonary artery pressure, decreased cardiac index, and increased pulmonary vascular resistance. During median follow-up of 4.6 years, 36% of the patients died. Decreased exercise capacity was associated with mortality (multivariable hazard ratio, 1.18; 95% CI, 1.01 to 1.37 for each 1-metabolic equivalent decrease in exercise capacity; P=0.031; P=0.052 after adjusting for invasive hemodynamic variables). Decreased exercise capacity also predicted mortality in functional classes I–II patients, 24% of whom died (hazard ratio, 1.53; 95% CI, 1.04 to 2.26 for each 1-metabolic equivalent decrease in exercise capacity; P=0.032), although this association did not persist after adjusting for invasive hemodynamic variables (P=0.63).
Conclusions— Reduced exercise capacity on exercise treadmill test is associated with worse hemodynamics and is a predictor of mortality in patients with pulmonary hypertension.
Key Words: pulmonary hypertension exercise hemodynamics mortality
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