Clinical, scintigraphic, and angiographic predictors of oxygen pulse abnormality in patients undergoing cardiopulmonary exercise testing

BackgroundThe oxygen (O-2) pulse curve obtained at cardiopulmonary exercise testing provides information on cardiorespiratory fitness and the presence of cardiovascular disease. O-2 pulse abnormalities have been attributed to myocardial ischemia, among other conditions, but the predictors of abnormal O-2 pulse curves are not completely known. HypothesisPerfusion abnormalities detected by myocardial perfusion scintigraphy (MPS) may be associated with abnormal O-2 pulse curves. MethodsForty patients with normal left ventricular function underwent cardiopulmonary exercise testing with radiotracer injection at peak exercise, followed by MPS. The O-2 pulse curves were classified as (A) normal; (B) probably normal (normal slope with lower peak value); (C) probably abnormal (flat, with low peak value); or (D) definitely abnormal (descending slope), and analyzed as A/B vs C/D. Coronary artery disease (CAD) was defined as >50% stenosis. MPS perfusion scores were calculated (summed rest score [SRS], indicating myocardial fibrosis; summed difference score, indicating ischemia). ResultsComparing patients with A/B vs C/D curves, the latter were more frequently female and had higher SRS. The prevalence of ischemic MPS, of any CAD, or multivessel CAD was not significantly different among patients with A/B or C/D curve patterns. On logistic regression, female sex, body mass index, and the SRS were significantly associated with C/D curves. ConclusionsFemale sex, increasing body mass index, and myocardial fibrosis were significant predictors of abnormal O-2 pulse curves. Myocardial ischemia and the presence and extent of CAD were not associated with the abnormal patterns of the O-2 pulse curve.