In Patients with Post-Infarction Left Ventricular Dysfunction, How Does Impaired Basal Rotation Affect Chronic Ischemic Mitral Regurgitation?

Background: The aim of this study was to explore the contribution of left ventricular (LV) basal rotation to the mechanism of chronic ischemic mitral regurgitation (MR).Methods: Fifty-seven patients (52 men; mean age, 68.3 +/- 11.8 years) with postinfarction LV dysfunction (defined as an ejection fraction <= 45%) were prospectively enrolled. Each invariably had functional MR. To assess MR degree, the effective regurgitant orifice area (EROA) was quantified by echocardiography using the proximal isovelocity surface area method. Furthermore, mitral valve deformation (valve tenting and annular function) and LV global (systolic and diastolic volumes, function, and sphericity) and local remodeling (displacement of papillary muscles, regional strain, and rotation by speckle-tracking) were assessed. The patients were subsequently subdivided into two groups according to the absence (group A) or presence (group B) on transthoracic echocardiography of infarct area in the inferior and/or posterior basal segments.Results: A larger EROA was found in group B than in group A (P = .034) and in subjects with asymmetric rather than symmetric tethering in either group (P = .036 and P = .040 for groups A and B, respectively). Basal radial (P = .009), circumferential (P = .042), and longitudinal (P =.005) strain and rotation (P = .021) were lower in group B than in group A. There was also a significant inverse correlation between EROA and basal rotation in group B (r = -0.75, P < .001). Furthermore, using multivariate linear regression analysis, we found that the independent determinants of EROA were end-diastolic volume (P < .001) and tenting area (P = .004) in group A and asymmetric tethering (P = .029) and basal rotation (P < .001) in group B.Conclusions: Impaired basal rotational mechanics occurring after an inferior-posterior myocardial infarction is associated with increased MR.