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

Background: The oxygen (O ) pulse curve obtained at cardiopulmonary exercise testing provides information on cardiorespiratory fitness and the presence of cardiovascular disease. O pulse abnormalities have been attributed to myocardial ischemia, among other conditions, but the predictors of abnormal O pulse curves are not completely known.

Hypothesis: Perfusion abnormalities detected by myocardial perfusion scintigraphy (MPS) may be associated with abnormal O pulse curves.

Methods: Forty patients with normal left ventricular function underwent cardiopulmonary exercise testing with radiotracer injection at peak exercise, followed by MPS. The O 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).

Results: Comparing 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.

Conclusions: Female sex, increasing body mass index, and myocardial fibrosis were significant predictors of abnormal O pulse curves. Myocardial ischemia and the presence and extent of CAD were not associated with the abnormal patterns of the O pulse curve.