Abstract 14166: Changes in Oxygen Pulse During Exercise can Identify Patients With Heart Failure With Preserved Ejection Fraction (HFpEF)
Introduction: Accurate identification of patients with HFpEF is challenging. Patient symptoms are subjective and objective markers can be confounded by age, body mass and relative fitness. Although exertional intolerance is a principal finding, there are limited non-invasive exercise measures unique in identifying HFpEF. We hypothesized changes in oxygen pulse (O2P) with exercise could differentiate HFpEF syndromes from age associated declines in fitness and cardiac function.
Methods and Results: Twelve (33% men) highly screened HFpEF subjects, 25 matched healthy controls who had 1) VO2max <80% age/sex predicted [LFIT; n=13] or 2) appropriate VO2max and low (lateral e’ < 7.5 cm/s) cardiac tissue Doppler [AFIT; n=12] were studied. Cardiac echo was performed at rest and exercise to exclude ischemia. AV nodal blocking agents were held 5 half-lives and subjects performed incremental stages of exercise to VO2max. VO2 (Douglas bags) and cardiac output (acetylene rebreathing) were measured at rest and during exercise. O2P was calculated as VO2/HR. O2P ratio (O2Psubmax/ O2Prest) during submaximal (~30% VO2max) and maximal exercise (O2Pmax/ O2Prest) was used to index changes from rest in each subject.
Relative fitness was similar in HFpEF and LFIT (67% vs. 70% of predicted VO2max). HFpEF had higher stroke volume during exercise compared to AFIT and LFIT. O2P ratio during sub- and maximal exercise were lower in HFpEF subjects (Figure), driven primarily by a higher resting O2P (3.9 vs. 2.5 ml/beat p<0.01). An O2P ratio cutoff of <2.5 for submaximal and <3.0 for maximal exercise provided a sensitivity of 75% and 83% with negative predictive value (NPV) of 88% and 91% respectively for detecting HFpEF.
Conclusion: Changes in O2P during sub- and maximal exercise can differentiate HFpEF from elderly individuals with either age/sex appropriate or low levels of VO2max with high NPV. O2P ratio during sub-maximal or maximal exercise may help to improve diagnostic accuracy for HFpEF.
- © 2013 by American Heart Association, Inc.