Mitral Valve Remodeling and Strain in Secondary Mitral Regurgitation: Comparison With Primary Regurgitation and Normal Valves.

OBJECTIVES: The aim of this study was to assess mitral valve (MV) remodeling and strain in patients with secondary mitral regurgitation (SMR) compared with primary MR (PMR) and normal valves. BACKGROUND: A paucity of data exists on MV strain during the cardiac cycle in humans. Real-time 3-dimensional (3D) echocardiography allows for dynamic MV imaging, enabling computerized modeling of MV function in normal and disease states. METHODS: Three-dimensional transesophageal echocardiography (TEE) was performed in a total of 106 subjects: 36 with SMR, 38 with PMR, and 32 with normal valves; MR severity was at least moderate in both MR groups. Valve geometric parameters were quantitated and patient-specific 3D MV models generated in systole using a dedicated software. Global and regional peak systolic MV strain was computed using a proprietary software. RESULTS: MV annular area was larger in both the SMR and PMR groups (12.7 ± 0.7 and 13.3 ± 0.7 cm2, respectively) compared with normal subjects (9.9 ± 0.3 cm2; p < 0.05). The leaflets also had significant remodeling, with total MV leaflet area larger in both SMR (16.2 ± 0.9 cm2) and PMR (15.6 ± 0.8 cm2) versus normal subjects (11.6 ± 0.4 cm2). Leaflets in SMR were thicker than those in normal subjects but slightly less than those with PMR posteriorly. Posterior leaflet strain was significantly higher than anterior leaflet strain in all 3 groups. Despite MV remodeling, strain in SMR (8.8 ± 0.3%) was overall similar to normal subjects (8.5 ± 0.2%), and both were lower than in PMR (12 ± 0.4%; p < 0.0001). Valve thickness, severity of MR, and primary etiology of MR were correlates of strain, with leaflet thickness being the multivariable parameter significantly associated with MV strain. In patients with less severe MR, anterior leaflet strain in SMR was lower than normal, whereas strain in PMR remained higher than normal. CONCLUSIONS: The MV in secondary MR remodels significantly and similarly to PMR with a resultant larger annular area, leaflet surface area, and leaflet thickness compared with that of normal subjects. Despite these changes, MV strain remains close to or in some instances lower than normal and is significantly lower than that of PMR. Strain determination has the potential to improve characterization of MV mechano-biologic properties in humans and to evaluate its prognostic impact in patients with MR, with or without valve interventions.

Valve Strain Quantitation in Normal Mitral Valves and Mitral Prolapse With Variable Degrees of Regurgitation.

OBJECTIVES: The aim of this study was to quantitate patient-specific mitral valve (MV) strain in normal valves and in patients with mitral valve prolapse with and without significant mitral regurgitation (MR) and assess the determinants of MV strain. BACKGROUND: Few data exist on MV deformation during systole in humans. Three-dimensional echocardiography allows for dynamic MV imaging, enabling digital modeling of MV function in health and disease. METHODS: Three-dimensional transesophageal echocardiography was performed in 82 patients, 32 with normal MV and 50 with mitral valve prolapse (MVP): 12 with mild mitral regurgitation or less (MVP - MR) and 38 with moderate MR or greater (MVP + MR). Three-dimensional MV models were generated, and the peak systolic strain of MV leaflets was computed on proprietary software. RESULTS: Left ventricular ejection fraction was normal in all groups. MV annular dimensions were largest in MVP + MR (annular area: 13.8 ± 0.7 cm2) and comparable in MVP - MR (10.6 ± 1 cm2) and normal valves (10.5 ± 0.3 cm2; analysis of variance: p < 0.001). Similarly, MV leaflet areas were largest in MVP + MR, particularly the posterior leaflet (8.7 ± 0.5 cm2); intermediate in MVP - MR (6.5 ± 0.7 cm2); and smallest in normal valves (5.5 ± 0.2 cm2; p < 0.0001). Strain was overall highest in MVP + MR and lowest in normal valves. Patients with MVP - MR had intermediate strain values that were higher than normal valves in the posterior leaflet (p = 0.001). On multivariable analysis, after adjustment for clinical and MV geometric parameters, leaflet thickness was the only parameter that was retained as being significantly correlated with mean MV strain (r = 0.34; p = 0.008). CONCLUSIONS: MVs that exhibit prolapse have higher strain compared to normal valves, particularly in the posterior leaflet. Although higher strain is observed with worsening MR and larger valves and annuli, mitral valve leaflet thickness-and, thus, underlying MV pathology-is the most significant independent determinant of valve deformation. Future studies are needed to assess the impact of MV strain determination on clinical outcome.

Comparative accuracy of two- and three-dimensional transthoracic and transesophageal echocardiography in identifying mitral valve pathology in patients undergoing mitral valve repair: initial observations.

BACKGROUND: Identification of mitral regurgitation (MR) mechanism and pathology are crucial for surgical repair. The aim of the present investigation was to evaluate the comparative accuracy of real-time three-dimensional (3D) transesophageal echocardiography (TEE) and transthoracic echocardiography (TTE) with two-dimensional (2D) TEE and TTE in diagnosing the mechanism of MR compared with the surgical standard. METHODS: Forty patients referred for surgical mitral valve repair were studied; 2D and 3D echocardiography with both TTE and TEE were performed preoperatively. Two independent observers reviewed the studies for MR pathology, functional or organic. In organic disease, the presence and localization of leaflet prolapse and/or flail were noted. Surgical findings served as the gold standard. RESULTS: There was 100% agreement in identifying functional versus organic MR among all four modalities. Overall, 2D TTE, 2D TEE, and 3D TEE performed similarly in identifying a prolapse or a flail leaflet; 3D TEE had the best agreement in identifying anterior leaflet prolapse, and it also showed an advantage for segmental analysis. Three-dimensional TTE was less sensitive and less accurate in identifying flail segments. CONCLUSION: All modalities were equally reliable in identifying functional MR. Both 2D TEE and 3D TEE were comparable in diagnosing MR mechanism, while 3D TEE had the advantage of better localizing the disease. With current technology, 3D TTE was the least reliable in identifying valve pathology.