Speaker: Nate Pack

Title: Is Post-Systolic Shortening a Reliable Indicator of Myocardial Viability? An MR Tagging and Late-Enhancement Study

Reference: (Salome Ryf et. al. JCMR 2006(8):445-451)

Introduction: During regional myocardial ischemia, a reduced deformation at end-systole and a continued shortening after systole, the so-called post-systolic shortening (PSS) can be observed. Despite experimental findings, the mechanism of PSS is still a matter of debate. Altered local activation or electromechanical coupling, delayed myocardial relaxation, or passive elastic recoil may cause this phenomenon. PSS has also been proposed as a marker of viability, and as such could predict recovery of LV function. Since viability is an important predictor of outcome, we performed the following study to clarify whether PSS is unambiguously related to viability or is caused by passive elastic recoil. Late enhancement (LE) MRI is a well accepted method to quantify transmural extent of scar in humans after myocardial infarction. To address the question of passive recoil as a possible mechanism causing PSS in patients with transmural scar in LE imaging, MR tagging was employed and analyzed using the HARP evaluation technique to measure systolic and post-systolic shortening in viable remote myocardium and transmural scar tissue. In addition, we were interested in which parameter extracted from tagging data is most powerful to describe the interactions between various myocadial segments, eg. between transmural scar tissue and remote viable myocardium.