Geometric Differences of the Mitral Apparatus Between Ischemic and Dilated Cardiomyopathy With Significant Mitral Regurgitation

Abstract

Background-This study was conducted to elucidate the geometric differences of the mitral apparatus in patients with significant mitral regurgitation caused by ischemic cardiomyopathy (ICM-MR) and by idiopathic dilated cardiomyopathy (DCM-MR) by use of real-time 3D echocardiography (RT3DE). Methods and Results-Twenty-six patients with ICM-MR caused by posterior infarction, 18 patients with DCM-MR, and 8 control subjects were studied. With the 3D software, commissure-commissure plane and 3 perpendicular anteroposterior (AP) planes were generated for imaging the medial, central, and lateral sides of the mitral valve (MV) during mid systole. In 3 AP planes, the angles between the annular plane and each leaflet (anterior, A␣; posterior, P␣) were measured. In ICM-MR, A␣ measured in the medial and central planes was significantly larger than that in the lateral plane (39Ϯ5°, 34Ϯ6°, and 27Ϯ5°, respectively; PϽ0.01), whereas P␣ showed no significant difference in any of the 3 AP planes (61Ϯ7°, 57Ϯ7°, and 56Ϯ7°, PϾ0.05). In DCM-MR, both A␣ (38Ϯ8°, 37Ϯ9°, and 36Ϯ7°, PϾ0.05) and P␣ (59Ϯ6°, 58Ϯ5°, and 57Ϯ6°, PϾ0.05) revealed no significant differences in the 3 planes. Conclusions-The pattern of MV deformation from the medial to the lateral side was asymmetrical in ICM-MR, whereas it was symmetrical in DCM-MR. RT3DE is a helpful tool for differentiating the geometry of the mitral apparatus between these 2 different types of functional mitral regurgitation.

Percutaneous Mitral Valve Repair for Chronic Ischemic Mitral Regurgitation

“…[7][8][9][10][11][12][13] Despite this mechanistic complexity, annuloplasty alone produces satisfactory reduction of IMR in up to 80% of cases. 21 This suggests that development of less invasive and safer methods of mitral annuloplasty might afford an important clinical benefit for large numbers of patients with IMR.…”

“…However, mechanisms that underlie these experimental forms of MR may differ from those present in chronic IMR. 10,13,[22][23][24] As for the difference between MR associated with global LV dysfunction and IMR, both MV anatomy 13 and mitral annular geometry 23 were different between them, suggesting potentially different approaches of PTMA in these 2 types of MR. As for the difference between acute and chronic IMR, it was demonstrated that fibrous annular perimeter was dilated and height of the mitral annulus was reduced in ovine models with chronic IMR, whereas they were unchanged in acute IMR. 24 Moreover, it is known that LV dilatation and corresponding mitral annular geometric change after MI play an important role in the production of chronic IMR.…”

“…[7][8][9][10][11][12][13] Using real-time 3D (RT3D) echocardiography, we demonstrated that medial MV tenting area (MVTa) is an important determinant of MR severity in IMR. 13 Clinical experience and experimental study, 14 however, have demonstrated that reducing the distance between the anterior and posterior annulus (A-P diameter) by surgical annuloplasty reduces or eliminates IMR. These findings are related because it is likely that increasing leaflet coaptation by reducing mitral annular A-P dimension simultaneously reduces tenting area.…”

“…Next, 3 A-P equidistant parallel planes perpendicular to the C-C plane were defined for imaging the geometry of the medial, central, and lateral sides of the mitral leaflets as described in our previous study ( Figure 1). 13 At mid systole, MVTa, the area enclosed by the annular plane and 2 leaflets, and MV tenting height (MVTht), the minimal distance between the leaflet coaptation and the mitral annular plane, were measured in all 3 A-P planes ( Figure 1). The same echocardiographic protocol was completed in 6 control sheep without MI to compare measurements between normal sheep and those with IMR.…”

The Emerging Role of Exercise Testing and Stress Echocardiography in Valvular Heart Disease

“…Patients with ischemic MR have more severe LV dysfunction compared with patients without associated MR, and the available data indicate that MR also confers a greater mortality risk and a greater risk of developing overt heart failure (57-60). MR arises in chronic CAD from global and regional LV remodeling (apical and posterior displacement of papillary muscles) leading to papillary muscle displacement, tenting of the mitral valve leaflets, and loss of systolic annular contraction (61)(62)(63). Hence, ischemic MR is primarily a disease of the LV myocardium, and therapies that produce beneficial reverse LV remodeling, such as myocardial revascularization (64), beta-blocker therapy (65), and cardiac resynchronization (66 -68), have the potential to reduce or eliminate MR.…”