Layer-specific quantification of myocardial deformation by strain echocardiography may reveal significant CAD in patients with non-ST-segment elevation acute coronary syndrome.

OBJECTIVES: Our objective was to assess whether patients with significant coronary artery disease (CAD) had reduced endocardial function assessed by layer-specific strain compared with patients without significant CAD.

BACKGROUND: The left ventricular (LV) wall of the heart comprises 3 myocardial layers. The endocardial layer is most susceptible to ischemic injury.

METHODS: Seventy-seven patients referred to coronary angiography due to suspected non-ST-segment elevation-acute coronary syndromes (NSTE-ACS) were prospectively included. Coronary occlusion was found in 28, significant stenosis in 21, and no stenosis in 28 patients. Echocardiography was performed 1 to 2 h before angiography. Layer-specific longitudinal and circumferential strains were assessed from endocardium, mid-myocardium, and epicardium by 2-dimensional (2D) speckle-tracking echocardiography (STE). Territorial longitudinal strain (TLS) was calculated based on the perfusion territories of the 3 major coronary arteries in a 16-segment LV model, whereas global circumferential strain (GCS) was averaged from 6 circumferential LV segments in all 3 layers.

RESULTS: Patients with significant CAD had worse function in all 3 myocardial layers assessed by TLS and GCS compared with patients without significant CAD. Endocardial TLS (mean -14.0 ± 3.3% vs. -19.2 ± 2.2%; p < 0.001) and GCS (mean -19.3 ± 4.0% vs. -24.3 ± 3.4%; p < 0.001) were most affected. The absolute differences between endocardial and epicardial TLS and GCS were lower in patients with significant CAD (Δ2.4 ± 3.6% and Δ6.7 ± 3.8%, respectively) than in those without significant CAD (Δ5.3 ± 2.1% and Δ10.4 ± 3.0%; p < 0.001). This reflects a pronounced decrease in endocardial function in patients with significant CAD. A receiver-operating characteristic curve analysis showed that endocardial and mid-myocardial TLS were superior to identify significant CAD compared with epicardial TLS (p < 0.05), wall motion score index (p < 0.01), and ejection fraction (EF) (p < 0.001).

CONCLUSIONS: Assessment of layer-specific strain by 2D-STE might identify NSTE-ACS patients with significant CAD. Endocardial function was more affected in patients with significant CAD compared with epicardial function and EF.