An Analysis of Myocardial Efficiency in Patients with Severe Asymptomatic Mitral Regurgitation

It is difficult to determine left ventricular systolic performance in patients with severe mitral regurgitation (MR) since left ventricular ejection fraction (EF) could be preserved until the end stages of the disease. Myocardial efficiency (MEf) describes the amount of external work (EW) done by the left ventricle per unit of oxygen consumed (mVO₂). In the present study, we aimed to investigate MEf in patients with asymptomatic severe MR using a novel echocardiographic method.

A total of 27 patients with severe asymptomatic MR and 26 healthy volunteers were included in this cross-sectional study. EW was measured using stroke volume and blood pressure, while mVO₂ was estimated using double product and left ventricular mass.

There were no differences between the groups with regards to EF (66% ± 5% vs. 69% ± 7%), while MEf was significantly reduced in patients with severe MR (25% ± 11% vs. 44% ± 12%, p < 0.001). This difference was maintained even after adjustment for age, gender and body surface area (adjusted x̅: 0.44, 95% CI: 0.39-0.49 for controls and adjusted x̅: 0.24, 95% CI: 0.19-0.29 for patients with severe MR). Further analysis showed that this reduction was due to an increase in total mVO₂ in the severe MR group. MEf of thepatients who were both on β-blockers and angiotensin converting enzyme inhibitors/angiotensin receptor blockers were higher than those who were not on any drugs, but this difference was not statistically significant (32% ± 15% vs. 23% ± 9%, p = 0.41).

MEf was significantly lower in patients with asymptomatic severe MR and preserved EF.