P676Left ventricular longitudinal mechanics and rotation are closely related to coronary flow reserve of the infarct related artery assessed non-invasively early after primary PCI


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Abstract

Background: From the pathophysiological background it is conceivable that in patients with acute MI treated with primary PCI anatomic integrity and functional status of the coronary microcirculation downstream from the opened IRA (infarct related artery) determine, at least partly, segmental and/or global myocardial function. Contemporary echocardiography offers non-invasive tools to evaluate this relation. Vector velocity Imaging (VVI) was shown to be useful in assessing the myocardial global and regional systolic function in post MI patients. Coronary Flow Reserve (CFR) of the IRA by transthoracic echocardiography, reflects status of the coronary microcirculation in post MI patients.Aim: to examine relation between early IRA CFR and left ventricular longitudinal strain, longitudinal strain rate and parameters of LV rotation.Methods: 29 patients with first anterior myocardial infarction successfully treated with primary PCI were examined 48h after primary PCI. Complete transthoracic echocardiographic study with LAD CFR during adenosine infusion (40 mcg/kg during 1 minute) was done using Sequoia 256 echo machine and post- processing was done using Syngo US workplace. Systolic and peak strain,systolic and diastolic strain rates(SR S; SR E and SR A)were measured as indices of longitudinal LV function in apical 4-, 2- and 3 chamber views. Global and territorial (for LAD territory) strain and SR were calculated. LV basal and apical rotations were measured and LV twist and torsion calculated.Results: both global and territorial peak and systolic strains were closely related to CFR-LAD (r between 0.58-0.63. p<0.03). From SR parameters global and territorial systolic SR significantly correlated to CFR-LAD (r= 0.638, p=0.02) and global SR-E showed less strong but still significant relation to CFR-LAD (r= 0.43, p=0.048). CFR-LAD showed very strong correlation with apical rotation (rotation angle:r=0.71, p= 0.001;early systolic rotation velocity r= 0.60, p= 0.005; late systolic rotation velocity r=0.65, p=0.018), LV twist (r=0.79, p<0.001) and LV torsion (r=0.724, p<0.001).Conclusion: contemporary echo-platform offers suitable non-invasive tool to assess relationship between coronary microcirculatory and myocardial function after reperfusion in STEMI patients. These results suggest that not only longitudinal subendocardial myocardial fibers, known to be vulnerable to ischemic events, are at strike during STEMI, but that oblique myocardial fiber responsible for LV rotation can be also injured during STEMI in the infarct zone, proportionally to the degree of infarct related coronary microcirculatory dysfunction.

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