Abstract 2293: Quantitative Assessment of Myocardial Infarction by Intracardiac Echocardiographic Speckle Tracking Imaging
Background: Measurement of 2D strain by speckle tracking imaging (STI) has proven to be a useful angle-independent method to noninvasively assess regional myocardial function. Our objective was to test STI in intracardiac echocardiography (ICE) and its ability to identify myocardial infarction.
Methods: The study included 10 dogs: 4 with normal hearts, and 6 with 6-wk old infarction created by permanent occlusion in mid LAD. A pair of segment-length crystals was placed in anterior mid LV of each normal dog to provide reference circumferential displacement during baseline as well as 2 different doses of dobutamine. An ICE catheter (9 F, 9 MHz) acquired short-axis views in mid LV in all dogs, and a custom algorithm applied STI offline. All comparisons were made at peak systolic strain.
Results: Circumferential strain by STI correlated well with strain by sonomicrometry (y=0.7x-2.4, n=12, r=0.91, P<0.001, FIG⇓). In normal hearts, radial strains were similar in anterior and posterior mid LV regions (12.5±2.4% vs. 11.3±3.8%), and circumferential strains were also similar in anterior and posterior LV (−9.7±1.3 vs. −9.9±3.5%). In infarcted hearts, STI showed −4.2±6.9% radial thinning in anterior mid LV vs. 16.4±10% thickening in posterior LV (P=0.021), and significant reduction in circumferential strain in anterior vs. posterior LV (−3.9±6.2% vs. −16.7±6.3%, P=0.037). Normal and infracted regions were confirmed by histological examination.
Conclusion: Determination of 2D myocardial strain by ICE speckle tracking is feasible. This novel approach may lead to improved quantification of LV function in combination with other diagnostic/imaging modalities during catheterization.