The Assessment of Left Ventricular Twist in Anterior Wall Myocardial Infarction Using Two-dimensional Speckle Tracking Imaging

Abstract

Two-dimensional speckle tracking imaging allows noninvasive measurement of left ventricular (LV) strain, rotation, and displacement. We investigated whether LV twist would be depressed in anterior wall myocardial infarction (MI) as a result of reduced apical rotation. Basal and apical LV short-axis images were acquired in 30 patients with anterior wall MI. Using commercially available 2-dimensional strain software, time domain speckle tracking was performed, and regional LV strain, rotation, and radial displacement were obtained in each plane. LV twist was defined as apical LV rotation relative to the base. Patients were divided into two groups according to global LV systolic function (normal LV ejection fraction [LVEF] group [LVEF > or = 45%, n = 16] and abnormal LVEF group [LVEF < 45%, n = 14]). Circumferential strain in the apex was significantly reduced in abnormal LVEF group compared with normal LVEF group (-7.3 +/- 2.6 vs -13.5 +/- 4.1, P < .001). Peak LV twist was significantly reduced in abnormal LVEF group (5.6 +/- 2.6 vs 9.8 +/- 4.0 degrees, P < .005) mainly because of reduced apical rotation. Peak positive and negative twist velocity was also significantly depressed (38.8 +/- 11.3 vs 52.1 +/- 19.3 degree/s, P < .05, and -42.6 +/- 17.8 vs -63.4 +/- 28.0 degree/s, P < .05, respectively). Significant correlation was noted between peak twist and LVEF (r = 0.73, P < .001) and LV end-systolic volume (r = 0.56, P < .001). The twist-displacement loop was markedly distorted in abnormal LVEF group. Systolic twist was decreased and diastolic untwisting was depressed in accordance with LV systolic dysfunction in anterior wall MI. These results suggest the significant impact of global LV systolic function on LV twist and twist-displacement loops in patients with anterior wall MI.