Flow adjusted transmitral pressure gradient as a modified indicator of functional mitral stenosis after repair for degenerative mitral regurgitation

Background and Aim After repair of degenerative mitral regurgitation (DMR), the focus is on functional mitral stenosis (FMS) when there is a decline of mitral hemodynamics. Yet, the clinical impacts and a standardized definition are still undecided. Since common mitral hemodynamic parameters are influenced by transmitral flow, the aim of this study is to seek the impact of flow adjusted transmitral pressure gradient (TMPG) by left ventricular stroke volume (LVSV) on the midterm outcomes. Methods Three hundred one patients who had undergone isolated mitral valve repair for degenerative lesions with annuloplasty prosthesis between October 2012 and June 2019 were included. Postoperative adverse events occurred in 20 patients (6.6%). Flow adjusted TMPG was defined as TMPG/LVSV. Results Common mitral hemodynamic parameters were not associated with adverse events. By multivariable analysis, patients' age, left ventricular ejection fraction (LVEF) and mean TMPG/LVSV were isolated as independent predictors (adjusted hazard ratio: 1.05, 0.95, and 1.16; p = .037, .005, and .035). Flow adjusted TMPG was significantly higher in the full ring group compared to the partial band group (0.051 mmHg/ml, [0.038-0.068] vs. 0.041 mmHg/ml, [0.031-0.056]; p < .001) and had a significantly negative correlation with the size of the annuloplasty prosthesis (r = -0.37, p < .001). Conclusions Conventional mitral hemodynamic parameters were not associated with adverse cardiac events after repair for DMR. Adjustment by flow has a potential to advance pressure gradient to a more sensitive indicator of FMS associated with clinical outcomes.