Asymmetric versus symmetric tethering patterns in ischemic mitral regurgitation: geometric differences from three-dimensional transesophageal echocardiography.
BACKGROUND: Ischemic mitral regurgitation (IMR) results from mitral leaflet tethering from left ventricular remodeling. Heterogeneity in local or global left ventricular remodeling can result in differential tethering patterns and affect mitral valve function and the degree of mitral regurgitation. The aims of this study were to compare mitral valve geometry in asymmetric and symmetric tethering patterns using three-dimensional transesophageal echocardiography and to examine the impact of tethering pattern on IMR severity. METHODS: Sixty-two patients with moderate or greater IMR underwent three-dimensional transesophageal echocardiography for the assessment of mitral valve geometry. Symmetric and asymmetric tethering patterns were determined by mitral regurgitation jet direction and coaptation of the mitral leaflets. The ratio of posterior to anterior leaflet tethering angle was a measure of tethering pattern (the higher the ratio, the more asymmetric the pattern). Overall tethering degree was assessed by tenting volume (TV). RESULTS: Compared with the symmetric group, the asymmetric group had less annular dilatation, greater annular heights (10.3 ± 1.9 vs 8.5 ± 1.9 mm, P < .01), greater ratios of posterior to anterior leaflet tethering angle (3.19 ± 0.88 vs 1.95 ± 0.46, P < .01), and smaller TVs with more posterior displacement of the coaptation line. Vena contracta normalized to TV was greater in the asymmetric group (0.38 ± 0.24 vs 0.19 ± 0.13 cm/mL, P < .01). Multivariate analysis showed that both ratio of posterior to anterior leaflet tethering angle (β = 0.46, P < .001) and TV (β = 0.41, P = .001) were predictors of IMR severity. CONCLUSIONS: Differences in mitral valve geometry are observed between asymmetric and symmetric tethering patterns in IMR. IMR degree is affected by both the pattern of tethering and the total degree of tethering. For the same degree of tethering, an asymmetric pattern is associated with increased MR severity. The pattern of mitral leaflet tethering may be considered in therapeutic decision making.
Zeng, X; Nunes, MCP; Dent, J; Gillam, L; Mathew, JP; Gammie, JS; Ascheim, DD; Moquete, E; Hung, J
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