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