Mitral systolic velocity at peak exercise predicts impaired exercise capacity in patients with heart failure with preserved ejection fraction

Background: Nearly half of patients with heart failure have normal left ventricular ejection fraction (LVEF), but their prognosis is no better than those with reduced LVEF. Although peak oxygen consumption (VO₂ ) is an independent predictor of mortality in heart failure, it is unclear how cardiac function during exercise contributes to peak VO₂ . Therefore, we explored the useful parameters measured by exercise stress echocardiography to predict peak VO₂ in patients with heart failure with preserved LVEF (HFpEF).

Methods and results: We assessed 80 patients being investigated for effort intolerance or dyspnea and finally analyzed 50 patients who satisfied the HFpEF criteria. Mean peak VO₂ was 16.4±2.8 mL/kg/min. Twenty-three patients (46.0%) achieved a peak VO₂ <16.0 mL/kg/min (Weber class C or D). There was a significant relationship between mitral systolic velocity (S') and cardiac output (CO) at rest (R=.55, P<.0001) and peak exercise (R=.64, P<.0001). The absolute increase in S' from rest to peak exercise also correlated with the absolute increase in CO (R=.32, P=.02). Multivariate logistic regression analysis showed that S' at peak exercise independently predicted peak VO₂ . Receiver-operator characteristic curve analysis identified that an S' at peak exercise of ≤8.13 cm/s predicted a peak VO₂ <16.0 mL/kg/min (sensitivity 95.7%, specificity 44.4%, area under curve 0.70, 95% confidence interval 0.55-0.84, P=.004).

Conclusions: Mitral systolic velocity at peak exercise accurately reflects peak VO₂ and may facilitate stratification of risk in patients with HFpEF.