Abstract
Abstract Funding Acknowledgements - Background Primary mitral regurgitation (MR) will cause volume overload to the left ventricle (LV) but due to systolic reguritant flow the pulmonary circulation will be affected often leading to post-capillary pulmonary hypertension and thus increased afterload to the right heart. As a consequence right ventricular (RV) dysfunction may be a consequence of MR. Purpose To assess the association between RV function assessed with cardiac magnetic resonance imaging (CMRI) and hemodynamics at rest and during exercise in ambulatory patients with primary mitral regurgitation (MR). Methods In an observational study, patients with significant primary MR with effective regurgitant orifice ≥0.30 cm2 and LV ejection fraction >60% were examined with right heart catheterization during rest and exercise and CMRI at rest. Patients were examined in semi-supine position (30 degree). From right heart catheterization pulmonary artery systolic pressure (PAPs) was measured, where RV stroke work index (RVSWI = 0.0136*(mean pulmonary artery pressure – right atrial pressure *stroke volume index) and pulmonary artery compliance (PAC= stroke volume / (PAPsystolic – PAPdiastolic)) was calculated. Patients were dichotomized according to effective regurgitant orifice (ERO) (≤0.4 cm2). Results The two groups (total n = 46) have same baseline characters with no significant differences. In both groups resting RVEF was normal and no difference in RV stroke volume was seen between the groups at rest or with exercise. However RVSWi was significantly higher in patients with ERO > 0.4, (rest p = 0.0039, exercise p = 0.01), Figure. The increase in RVSWi was driven by increased sPAP and where significantly in ERO > 0.4 at rest at during exercise (rest p = 0.00027, exercise p = 0.0352). At rest PAC was significantly higher in ERO above 0.4, but during exercise no differences was found in the two groups. RVEF at rest measured by CMRI showed no correlation with RVSWi in the two groups (r = 0.11, p = 0.45) Conclusion In ambulatory patients with mitral regurgitation above 0.4 cm2, RVSW is associated with an increased right ventricle workload and contractility at rest and during exercise which especially is driven by increased post capillary pressure whereas pulmonary arterial compliance only is mildly affected. Abstract P1425 Figure. Ventricle function at rest/exercise
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