Strain Imaging - Revealing the Heart Dance

Myocardial stiffness which is increased during ischemia, might recover or remain as myocardial infarction (MI). Since it is essential to differentiate between these situations, we hypothesized that it is possible to predict the transmurality of MI by using circumferential strain rate. Occlusion of the LAD for 30 minutes followed by reperfusion was applied to 19 rats. Short axis scans were acquired at baseline, 20 minutes and two weeks post-MI. The scans were post-processed to measure the strain and strain rate. Thereafter, the rats were sacrificed to perform histological analysis of MI transmurality. This analysis showed that 6 rats developed transmural MI and 13 developed small non-transmural MI. Twenty minutes post-MI the A wave of the transmural MI group decreased from baseline (P<0.01), while the A wave of the non-transmural MI group did not change. The strain did not decrease from baseline at this time. Two weeks post-MI, the peak global strain and A wave decreased only for the transmural group (P<0.01), while the S wave decreased for both groups (P<0.01). The strain rate A accurately differentiates between rats that will develop transmural vs. non transmural MI.