Usefulness of Vena Contracta for Identifying Severe Secondary Mitral Regurgitation: A Three-Dimensional Transesophageal Echocardiography Study

Abstract

Background: In secondary mitral regurgitation (SMR), effective regurgitant orifice area by the proximal isovelocity surface area method ( ${\mathrm{EROA}}_{\text{PISA}}$ ) evaluation might cause an underestimation of regurgitant orifice area because of its ellipticity compared with vena contracta area (VCA). We aimed to reassess the SMR severity using VCA-related parameters and ${\mathrm{EROA}}_{\text{PISA}}$ .

Methods: The three-dimensional transesophageal echocardiography data of 128 patients with SMR were retrospectively analyzed; the following parameters were evaluated: ${\mathrm{EROA}}_{\text{PISA}}$ , anteroposterior and mediolateral vena contracta widths (VCWs) of VCA (i.e., ${\mathrm{VCW}}_{\text{AP}}$ and ${\mathrm{VCW}}_{\text{ML}}$ ), ${\mathrm{VCW}}_{\text{Average}}$ calculated as ( ${\mathrm{VCW}}_{\text{AP}}$ + ${\mathrm{VCW}}_{\text{ML}}$ )/2, and ${\mathrm{VCA}}_{\text{Ellipse}}$ calculated as $\pi$ $\times$ ( ${\mathrm{VCW}}_{\text{AP}}$ /2) $\times$ ( ${\mathrm{VCW}}_{\text{ML}}$ /2). Severe SMR was defined as $\ge$ 0.39 ${\mathrm{cm}}^2$ .

Results: The mean age of the patients was 77.0 $\pm$ 8.9 years, and 78 (60.9%) were males. Compared with ${\mathrm{EROA}}_{\text{PISA}}$ (r = 0.801), ${\mathrm{VCW}}_{\text{Average}}$ (r = 0.940) and ${\mathrm{VCA}}_{\text{Ellipse}}$ (r = 0.980) were strongly correlated with VCA. On receiver-operating characteristic curve analysis, ${\mathrm{VCW}}_{\text{Average}}$ and ${\mathrm{VCA}}_{\text{Ellipse}}$ had C-statistics of 0.981 (95% confidence interval [CI], 0.963-1.000) and 0.985 (95% CI, 0.970-1.000), respectively; these were significantly higher than 0.910 (95% CI, 0.859-0.961) in ${\mathrm{EROA}}_{\text{PISA}}$ (p = 0.007 and p = 0.003, respectively). The best cutoff values for severe SMR of ${\mathrm{VCW}}_{\text{Average}}$ and ${\mathrm{VCA}}_{\text{Ellipse}}$ were 0.78 cm and 0.42 ${\mathrm{cm}}^2$ , respectively. The prevalence of severe SMR significantly increased with an increase in ${\mathrm{EROA}}_{\text{PISA}}$ (38 of 88 [43.2%] patients with ${\mathrm{EROA}}_{\text{PISA}}$ $<$ 0.30 ${\mathrm{cm}}^2$ , 21 of 24 [87.5%] patients with ${\mathrm{EROA}}_{\text{PISA}}$ = 0.30-0.40 ${\mathrm{cm}}^2$ , and 16 of 16 [100%] patients with ${\mathrm{EROA}}_{\text{PISA}}$ $\ge$ 0.40 ${\mathrm{cm}}^2$ [Cochran-Armitage test; p $<$ 0.001]). Among patients with ${\mathrm{EROA}}_{\text{PISA}}$ $<$ 0.30 ${\mathrm{cm}}^2$ , SMR severity based on VCA was accurately reclassified using ${\mathrm{VCW}}_{\text{Average}}$ (McNemar's test; p = 0.505) and ${\mathrm{VCA}}_{\text{Ellipse}}$ (p = 0.182).

Conclusions: Among patients who had SMR with ${\mathrm{EROA}}_{\text{PISA}}$ of $<$ 0.30 ${\mathrm{cm}}^2$ , suggestive of moderate or less SMR according to current guidelines, $>$ 40% had discordantly severe SMR based on VCA. ${\mathrm{VCW}}_{\text{Average}}$ and ${\mathrm{VCA}}_{\text{Ellipse}}$ values were useful for identifying severe SMR based on VCA in these patients.

Keywords: effective regurgitant orifice area; secondary mitral regurgitation; vena contracta area; vena contracta width.