Noninvasive Separation of Large, Medium, and Small Myocardial Infarcts in Survivors of Reperfused ST-Elevation Myocardial Infarction

Abstract

Background— The objective of the study was to evaluate the ability of established and new parameters of global systolic left ventricle function to estimate myocardial infarct size. Increasing infarct extent is associated with impaired prognosis in chronic ischemic heart disease. Systolic myocardial deformation is a complex 3D process that is mainly influenced by the amount and transmural distribution of viable myocardium. Speckle-tracking echocardiography (2D-STE) enables deformation assessment along the 3 main cardiac axes independent of insonation angle. Methods and Results— Global longitudinal, circumferential, and radial strain and left ventricle twist by 2D-STE, global longitudinal strain rate and strain by tissue Doppler imaging, and left ventricle ejection fraction and wall motion score index were assessed in 40 patients 8.5�5.4 months after a first myocardial infarct and compared with global myocardial infarct mass assessed by contrast-enhanced MRI. Longitudinal and circumferential strain by 2D-STE and longitudinal strain and strain rate by tissue Doppler imaging significantly separated medium-sized infarcts from small or large infarcts at the global level ( P <0.05). All deformation indices correlated significantly with global infarct mass ( P <0.01). Circumferential and longitudinal strains by 2D-STE demonstrated the best ability to identify medium-sized global myocardial infarcts. Conclusions— Circumferential and longitudinal strains by 2D-STE correlate with myocardial infarct mass and significantly differentiate among large, medium, and small myocardial infarcts.