Prognostic impact of biplane vena contracta width in patients with atrial functional mitral regurgitation

BACKGROUND: The vena contracta width (VCW) in parasternal long axis view (PLAX-VCW) and effective regurgitant orifice area (EROA) may underestimate the mitral regurgitation (MR) severity because of the elliptical-shaped effective orifice in atrial functional MR (AFMR). We aimed to assess the association between the vena contracta width by biplane method (Bi-VCW) and clinical outcomes in patients with AFMR and to compare the discriminative ability of Bi- VCW with those of other quantitative/semiquantitative metrics. METHODS: This was a substudy of a multicentre registry of moderate or severe AFMR. The Bi-VCW was evaluated as the average of the apical two-chamber and four-chamber views. The primary outcome was a composite of all-cause mortality, heart failure hospitalization, and mitral valve interventions. RESULTS: Among 423 studied patients, the Bi-VCW was higher than PLAX-VCW (8.1 ± 2.4 vs. 4.8 ± 1.9 mm, p < 0.001); the guideline-recommended threshold of Bi-VCW of >8.0 mm stratified 48% as severe MR. The Bi-VCW showed the highest discriminatory performance of the primary outcome (area under the time-dependent receiver operating characteristic curve of 0.76) compared with the PLAX-VCW and EROA and revealed an optimal threshold of 7.9 mm (sensitivity, 76%; specificity, 65%). In the multivariable Cox proportional hazards model, Bi- VCW >8.0 mm was independently associated with a higher risk of the primary outcome (adjusted hazard ratio=2.97, 95% confidence interval: 2.04-4.32, p < 0.001). CONCLUSIONS: The Bi-VCW was independently associated with poorer outcomes in patients with AFMR and demonstrated superiority over the guideline-recommended parameters. It could serve as an independent and first surrogate for risk stratification in patients with AFMR.