How ischemia affect the distribution of myocardial deformation parameters according to long term progression of regional kinetics in patients with acute and chronic myocardial infarction?

Abstract

The aim was to examine the effects of ischemia on distribution of myocardial deformation parapameters- longitudinal, circumferential and radial strain for assessment of myocardial function in patients with ST- segment elevation acute myocardial infarction (STEMI)by 2 dimensional speckle tracking and compare these parameters with 4 months follow up (4mFU) after a primary coronary intervention (PCI) Methods: 20normal volunteers (ages 31y±5)and 30 patients (ages 63±13)with AMI in the first 24 hours after PCI, were enrolled in this study.Standard echocardiography was performed in first hours (baseline)and 4mFU and B-mode gray scale (frame rate-65±7frames/s)were aquired in the apical 2-,4 and 4C view and parasternal short axis view.The strain curves (ɛLL, ɛCC, ɛRR)were extracted and derived using VVI software in18 segments left ventricle model.The i.c. ECG was performed during PCI procedure, placing the coronary guidewire tip in all branches>1.5mm, making a mapof residual ischemic region expressed in same 18 segment model.ST-segment resolution less than 70% was accepted as a marker of necrosis in a given segment. Results: After infarct, adverse remodeling (progressive increasing inLV size and reduced EF)was found.The radial and circumferential strain decreased in the infarct (32.2±8.7;-11.3±2.1),perinfarct (39.6±8.2; 13.1±2.3) and remote (41.1±6.4;-13.9±2.0) regions acutely comparable with normals (51.06±4.95;-20.91±.76).The longitudinal strain was only significantly decreased in infarct regions at baseline (-8.3±1.2;-13.3±2.1;-13.9±2.2) and 4mFU (-11.3±2.0;-17.5±2.2;-18.78±1.8).Circumferential and radial strain after 4mFU were reduced in the infarcted (-13.6±2.2; 38.3±3.6)segments, but in perinfarcted (-15.8±3.4; 41.2±5.78)were bellow normals, inremote (-18.4±2.2; 45.6±8.2) close to the normals.There was a significant correlation between the infarct size (31,1±3,4%) and longitudinal strain (r=-0.49,p<0.01),radial strain (r=-0.37,p<0,01)and circumferential strain (r=0.39,p<0.05). Conclusions: All indices of myocardial function demonstrate reduced systolic deformation in infarcted myocardium.The deformation gradually reduces with increasing infarct size and transmural distribution.Ischemic tissue is characterized by reduced peak deformation and altered deformation pattern.STE enables quantification of regional myocardial function in pts with acute and chronic myocardial infarction.The longitudinal strain early after reperfusion may predict infarct size and LV remodeling;radial and circumferential strain in perinfarct and remote regions-adverse left ventricular remodeling and progression to ischemic cardiomyopathy.