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

Purpose Oxygen pulse (O 2 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 O 2 pulse and stroke volume (SV) measured using an accepted technique, echocardiography, at rest and during exercise. Methods Eighteen HFpEF (EF=62±1%) patients and 26 healthy controls (CTL) completed an exercise test on a cycle ergometer. Average measures of oxygen consumption (VO 2 , metabolic cart), heart rate (HR, 12‐lead ECG), and SV (transthoracic echocardiography) were taken at rest and peak exercise. O 2 pulse was calculated as VO 2 divided by HR. Results O 2 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). O 2 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). Conclusion Our results demonstrate a moderate relationship between O 2 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.