Abstract 1417: Combined Assessment of Left Ventricular Strain and Rotation - A Novel Approach for Assessment of Function in Infarcted Myocardium and its Border Zones

Abstract

Background : LV circumferential strain and rotation are markers of myocardial function, but the two measures dissociate in the ischemic LV. This study investigates the mechanism and clinical significance of this dissociation. Methods : In healthy subjects (n=15) and patients with LAD-related myocardial infarction (n=15), LV apical rotation and strain were measured from apical short-axis recordings by STE and MRI tagging. Infarct extent was determined by contrast MRI. To define mechanisms of the dissociation between strain and rotation we used a finite element model. Results : Mean apical rotation and strain by STE were lower in the patients than in healthy subjects (13±4 vs. 10±5° and −24±2 vs. −12±10%, respectively, P <0.05). In patients, segmental strain was reduced in proportion to extent of infarction (r=0.84, P <0.0001). Maximum and minimum rotation, however, were found at the infarct borders; maximum rotation at the border in direction of rotation (counter-clockwise) and minimum rotation at the opposite infarct border (Figure ). The simulation study reproduced the clinical findings and indicated that the dissociation was mainly caused by mechanical interactions between infarcted and viable myocardium transmitted along circumferentially oriented LV fibers. Conclusions : Systolic strain reflects regional myocardial function and infarct extent, while systolic rotation defines infarct borders. Strain and rotation provides complementary information in assessment of myocardial dysfunction and infarct extent.