Abstract 1877: Experimental Validation of Circumferential Subendocardial and Subepicardial Myocardial Strain during Dobutamine Stress Echocardiography in Ischemic Conditions
Background: Strain echocardiographic techniques have been developed in order to quantify myocardial contraction but are currently based on a transmural myocardial analysis whereas subendocardial (ENDO) and subepicardial (EPI) layers have different response to ischemia. Recent development in strain software enables to investigate simultaneously strain in 2 myocardial layers.
Objectives: To assess and validate this new tool for the detection of ischemia during dobutamine stress echocardiography (DSE).
Methods: In 6 open-chest anesthetized pigs, circumferential strain (CS) was studied before and during dobutamine infusion, in absence of coronary stenosis and in ischemic conditions produced by: 2 degrees of non flow-limiting stenoses reducing left anterior descending (LAD) artery hyperemic flow by 20% and then by 60% (NFLS20 and NFLS60), and 1 flow-limiting stenosis reducing resting LAD flow by 25% (FLS25). Agreement between CS echocardiography in ENDO and EPI layers in risk area (RA) and sonomicrometry was evaluated by linear regression and Bland-Altman analysis. CS in ENDO and EPI layers were studied in absence or coronary stenosis and in ischemic condition, in RA and in control area (CA).
Results: Good correlations and agreements were observed between echocardiography and sonomicrometry at rest and during dobutamine : ENDO CS: r=0.66, P<0.001 and r=0.69, P<0.0001; EPI CS: r=0.65, P<0.01 and r=0.62, P<0.001. At rest, both ENDO and EPI CS in the RA were significantly decreased in the presence of FLS25. During dobutamine infusion, ENDO CS was significantly reduced in the presence of NFLS20 and EPI CS in the presence of NFLS60.
Conclusions: Multilayer strain echocardiography provides accurate assessment of LV regional function. Evaluation of ENDO and EPI strains during DSE has real potential to improve detection of ischemia in clinical practice.