Papillary muscle dysfunction attenuates ischemic mitral regurgitation in patients with localized basal inferior left ventricular remodeling: insights from tissue Doppler strain imaging.

OBJECTIVES: The purpose of this research was to test whether papillary muscle (PM) dysfunction attenuates ischemic mitral regurgitation (MR) in patients with left ventricular (LV) remodeling of a similar location and extent. BACKGROUND: Papillary muscle dysfunction could attenuate tethering and MR because of PM elongation. However, variability in the associated LV remodeling, which exaggerates tethering, can influence the relationship between PM dysfunction and MR. METHODS: In 40 patients with a previous inferior myocardial infarction but without other lesions, the LV volume, sphericity, PM tethering distance, PM longitudinal systolic strain, and MR fraction were quantified by echocardiography. The patients were divided into two groups: group 1 with significant basal inferoposterior LV bulging but without advanced LV bulging involving other territories, therefore with a similar location and extent of LV remodeling, and group 2 without significant LV bulging. RESULTS: The medial PM tethering distance was significantly correlated with the %MR fraction (r2 = 0.64, p < 0.01), and multiple regression analysis identified an increase in the tethering distance as the only independent determinant of the MR fraction in all subjects and also in group 1. The PM longitudinal systolic strain had no significant relationships with MR fraction in all subjects with variable degrees of LV remodeling, but it had a significant inverse correlation with the MR fraction (r2 = 0.33, p < 0.01) in group 1 with LV remodeling of a similar location and extent, indicating that PM dysfunction is associated with less MR. CONCLUSIONS: Papillary muscle dysfunction, reducing its longitudinal contraction to induce leaflet tethering, attenuates ischemic MR in patients with basal inferior LV remodeling.