Aims: Management of patients with mitral stenosis (MS) relies on accurate evaluation of the mitral valve area (MVA). Planimetry (MVA(2D)) is considered as the reference method but must be performed at the tips of the leaflets with the correct plane orientation and therefore requires experienced operators. Real-time three-dimensional echocardiography (RT3DE) may overcome this limitation but its usefulness for experienced when compared with less experienced operators has not been evaluated. In addition, superiority of RT3DE for the evaluation of commissural splitting after percutaneous mitral commissurotomy (PMC) is unknown.
Methods and results: 60 patients were prospectively evaluated by 2D and RT3DE before and after PMC by experienced operators. Before PMC, MVA(3D) was slightly higher than MVA(2D) (1.15 +/- 0.25 vs. 1.06 +/- 0.22 cm2, P = 0.0001) but correlation between methods was excellent (r = 0.73, P < 0.0001), mean difference was small (0.09 +/- 0.18 cm2) and clinically meaningless (three patients misclassified, two of whom had borderline MS severity). After PMC, MVA(3D) did not differ from and correlated well with MVA(2D) (1.87 +/- 0.37 vs. 1.85 +/- 0.32 cm2, P = 0.36; r = 0.76, P < 0.0001; mean difference 0.03 +/- 0.24 cm2). Twenty-five additional patients were also evaluated both by an experienced and a less experienced operators. Bland-Altman analysis showed the better agreement between MVA(3D) measured by the less experienced operator and MVA(2D) measured by the experienced operator than between MVA(2D) measured by the less experienced and the experienced operators (mean difference 0.03 +/- 0.34 vs. - 0.13 +/- 0.46 cm2, P = 0.03). When compared with RT3DE, 2DE underestimated the degree of commissural opening in 33% of patients and agreement between methods was weak (kappa = 0.41).
Conclusion: RT3DE provides accurate MVA measurements similar to 2D planimetry performed by experienced operators. Thus, it does not provide a real advantage for experienced operators, whereas it seems particularly helpful for less experienced operators. In addition, RT3DE improves the description of valvular anatomy.