Aortic stiffness plays a role in the discrepancy between mitral valve lesion severity and hemodynamic burden of secondary mitral regurgitation

Background: By the framework of proportionate/disproportionate secondary mitral regurgitation (sMR), disproportionate sMR is characterized by a low left ventricular stroke volume (SV) and an out of proportion regurgitant fraction (RF) for the same effective regurgitant orifice area (EROA). The degree of aortic stiffness is a determinant of the ventricular forward SV. We aim to analyze the importance of aortic stiffness in influencing the discrepancy between measures of mitral valve lesion severity (EROA) and sMR hemodynamic burden (regurgitant volume [RV] and RF).Methods: We enrolled stable patients with heart failure with reduced ejection fraction (HFrEF) and at least mild sMR. Mitral EROA, RV, RF and aortic pulse wave velocity (PWV) were measured by echocardiography. We defined three groups based on the degree of actual RF deviation from RF estimated by the linear regression equation of RF on EROA (concordant, low-discordant [residuals lower-than -5%] and high-discordant RF [residuals higher-than 5%]). Results: 117 patients were analyzed (68 +/- 13 years; female 30%; LVEF 33 +/- 8%; EROA 16 +/- 12mm2; RV 24 +/- 15 ml; RF 27 +/- 13%; PWV 6.6 +/- 3.2 m/s). LVEF, end-diastolic-volume and EROA didn't differ among groups. PWV and RV were higher in patients with high-discordant RF (p <= 0.01), whereas total left ventricular-SV and left ventricular outflow tract-SV (LVOT-SV) were lower (p <= 0.0004). PWV was associated with LVOT-SV (r=-0.3;p = 0.0008) and RV (r = 0.3;p = 0.0009). High-discordant RF was predicted by PWV (p = 0.001) independently of LVOT-SV and RV.Conclusion: In this HFrEF cohort with sMR, higher PWV was associated with higher-than-expected RF for a given EROA. Aortic stiffness might play a role in the discrepancy between mitral valve lesion severity and sMR hemodynamic burden.