Relationship between oxygen pulse and echocardiography in heart failure with preserved ejection fraction

Abstract

PurposeOxygen pulse (O2 pulse) is often used clinically as a surrogate for stroke volume during cardiopulmonary exercise testing; however, little data exists on the validity of this measure in patient populations (e.g. heart failure with preserved ejection fraction – HFpEF). Therefore, the purpose of this study was to examine the relationship between O2 pulse and stroke volume (SV) measured using an accepted technique, echocardiography, at rest and during exercise.MethodsEighteen HFpEF (EF=62±1%) patients and 26 healthy controls (CTL) completed an exercise test on a cycle ergometer. Average measures of oxygen consumption (VO2, metabolic cart), heart rate (HR, 12‐lead ECG), and SV (transthoracic echocardiography) were taken at rest and peak exercise. O2 pulse was calculated as VO2 divided by HR.ResultsO2 pulse was significantly correlated with SV at rest and at peak exercise in CTL (r=0.60 and r=0.55, p<0.05 for both respectfully). O2 pulse was similarly significantly correlated with SV at rest in HFpEF (r=0.58, p<0.05) whereas this relationship demonstrated a trend at peak exercise (r=0.44, p=0.06).ConclusionOur results demonstrate a moderate relationship between O2 pulse and SV measured using echocardiography in healthy control participants at rest and during exercise. There is a similar relationship at rest in patients with HFpEF; however, this relationship is less strong during exercise.