Quantitative Speckle Tracking Strain Analysis Of Border And Remote Left Ventricular Regions After An Infero-Lateral Myocardial Infarction In A Chronic Swine Model

Introduction: A myocardial infarction (MI) imposes a significant pathological load on the viable myocardium, leading to an acutely adaptive response and chronically maladaptive remodeling. In patients with an inferolateral MI, the mechanical load on the remote regions is significant, and thus the resulting ventricular remodeling is extensive and often leading to congestive heart failure. In this study, we used 3D echocardiography combined with speckle tracking strain to quantify the myocardial strains of the remote and border zone in an inferolateral MI swine. Hypothesis: An inferolateral MI imposes significant changes in myocardial strains is not only the border zone but also the remote regions. Methods: Six swine were induced with an inferolateral MI by ethanol injection. The animals were survived to 10 weeks post-infarction. Nine healthy swine were used as controls. Both animal groups underwent cardiac echocardiography with Siemens, by tunneling of a transesophageal probe into the thoracic cavity for direct placement onto the left atrium, such that the entire left heart was imaged. Strain analysis was performed with eSie LV analysis (Figure A). Results: EF was significantly lower than the control group (43.0±8.2% vs 52.2±5.2%, p=0.0190). EDV and ESV in the MI group were greater compared to the control group (127.8±32.0 ml vs 81.9±19.2 ml, p=0.0040, and 74.5±28.6 ml vs 38.5±6.8 ml, p=0.0027, respectively) indicative of remodeling. Circumferential end-systolic strains of basal- and mid-inferolateral wall in the MI group were significantly reduced compared to the control group (24.1±20.0% vs 48.0±18.6%, p=0.0339 and 10.5±11.4% vs 27.8±12.8%, p=0.0186, respectively). Similarly, longitudinal strain in mid-inferolateral wall in the MI group was significantly reduced (-7.8±5.8% vs -16.3±12.8%, p=0.0120) (Figure B, C). Conclusion: Reduction in both circumferential and longitudinal strains were observed in the border zone, but not in the remote zone.