Transmural Peak Systolic Strain and Strain Rate Predict Transmural Myocardial Blood Flow in a Pig Myocardial Infarction Model

Abstract

Objective: To test the hypothesis that the transmural variation of the longitudinal myocardial peak systolic strain (Sp) and strain rate (SRp) can predict the transmural distribution of myocardial blood flow (MBF) in a pig model of acute myocardial infarction. Methods: The longitudinal Sp and SRp were measured by echocardiography in both subendocardium (Sp-endo, SRp-endo) and subepicardium (Sp-epi, SRp-epi) in the normal, ischemic and infarct segments, respectively. The MBF in corresponding sites was measured by colored microspheres technique. The subendocardial to subepicardial ratio of Sp (Sp-EER), SRp (SRp-EER) and MBF (MBF-EER) were calculated. Results: In the normal segments, Sp-endo and SRp-endo were significantly higher than Sp-epi and SRp-ep, respectively. In the ischemic segments, Sp-endo and SRp-endo decreased to a greater extent than Sp-epi and SRp-epi, respectively. In the infarct segments, Sp-endo, SRp-endo Sp-epi and SRp-epi were all remarkably reduced. High correlations were found between Sp and SRp measurements and MBF in both subendocardium and subepicardium (r = –0.75 to –0.84, p < 0.001). Conclusion: Strain and strain rate imaging provides a reliable approach to the noninvasive estimation of the transmural blood distribution across the normal, ischemic and infarct segments.