A Novel Assessment Using Projected Transmitral Gradient Improves Diagnostic Yield of Doppler Hemodynamics in Rheumatic and Calcific Mitral Stenosis

Objectives: The aims of this study were to: 1) develop a formula for projected transmitral gradient (TMG), expected gradient under normal heart rate (HR), and stroke volume (SV); and 2) assess the prognostic value of projected TMG.

Background: In mitral stenosis (MS), TMG is highly dependent on hemodynamics, often leading to discordance between TMG and mitral valve area.

Methods: All patients with suspected MS based on echocardiography from 2001 to 2017 were analyzed. Data were randomly split (2:1); projected TMG was modeled in the derivation cohort, then tested in the validation cohort. The composite endpoint was death or mitral valve intervention.

Results: Of 4,973 patients with suspected MS, severe and moderate MS, defined as mitral valve area ≤1.5 and >1.5 to 2.0 cm², were present in 437 (9%) and 936 (19%), respectively. In the derivation cohort (n = 3,315; age 73 ± 12 years; 34% male), corresponding gradients were TMG ≥6 and 4 to <6 mm Hg, respectively, under normal hemodynamics. Based on the impact of hemodynamics on TMG, the formula was projected TMG = TMG - 0.07 (HR - 70) - 0.03 (SV - 97) in men and projected TMG = TMG - 0.08 (HR - 72) - 0.04 (SV - 84) in women. In the validation cohort (n = 1,658), projected TMG had better agreement with MS severity than TMG (kappa 0.61 vs. 0.28). Among 281 patients with TMG ≥6 mm Hg, projected TMG ≥6 mm Hg, present in 171 patients (61%), was associated with higher probability of the endpoint versus projected TMG <6 mm Hg (adjusted hazard ratio: 1.8; 95% confidence interval: 1.2 to 2.6; p < 0.01).

Conclusions: The novel concept of projected TMG, constructed using the observed impact of HR and SV on TMG, significantly improved the concordance of gradient and valve area in MS and provided better risk stratification than TMG.