Background: The main objective of our study was to identify, by means of global longitudinal strain (GLS), territorial strain (TS), and postsystolic shortening (PSS) of left ventricle, which patients with acute coronary syndrome without ST elevation (NSTE-ACS) had ≥ 70% coronary stenosis. Methods: One hundred patients (PTS) with diagnosis of NSTE-ACS were stratified according to GRACE risk score, and underwent coronary angiography. GLS and TS were calculated. We also evaluated the strain curves in the 18 segments to identify the presence of the PSS and to calculate the post systolic index (PSI). Results: Mean age was 60 ± 11. 4, 62% was male. The majority were low and moderate cardiovascular risk. They were divided into group A (34 PTS) with coronary stenosis<70% and group B (66 PTS) with coronary stenosis ≥ 70%. Clinical score was higher in group B (GRACE=88. 7 ± 24. 18, p=0. 040) and 98. 5% was in low/moderate risk by GRACE score. GLS allowed the identification of PTS with coronary stenosis ≥ 70% in this group (AUC=0. 72, p=0. 001, sensitivity=58%, specificity=88%, positive predictive value=75. 1% and negative predictive value=74. 9%). Regarding the TS, the accuracy to determine coronary stenosis ≥ 70% was 0. 70 (p=0,001). The accuracy of the PSS in detecting coronary stenosis ≥ 70% was 69. 3%, with sensitivity estimated at 73. 3% and specificity at 60. 7%. Conclusion: The GLS, territorial strain, and PSS may improve the detection of severe coronary stenosis in patients with low/moderate risk by GRACE risk score. Thus, it can be an additional tool for a better stratification of such patients in the emergency unit.

Patients with acute coronary syndrome without ST segment elevation (NSTE-ACS) have a wide spectrum of severity, which varies according to clinical and laboratory characteristics [1]. For this reason, early risk stratification, using clinical scores, is considered Class I recommendation, which enables the probability estimate of adverse cardiovascular events in order to determine the best treatment strategy. In addition, it enables a more cost-effectiveness approach during patients’ treatment. The Global Registry of Acute Coronary Events (GRACE) risk score is the most usual one, and their prognostic value was established by prospective cohort studies. The GRACE risk score has been shown to have good ability to assess risk for death in patients presenting with acute coronary syndrome, with eight factors based on the characteristic clinical presentation and biomarker results of the patients. It enables the stratification of patients with low, moderate, and high cardiovascular risk. Two-dimensional longitudinal strain enables the quantification of global and territorial myocardial deformity by tracking natural "acoustic tags" in the heart muscle by ultrasound, with lower absolute values in the presence of myocardial ischemia. Quantitative assessment of longitudinal deformation measures and myocardial velocity have allowed identification of even subtle changes in the contractile function, such as post systolic shortening. Studies have shown that post systolic shortening has been reported useful for detection of acute ischemia and superior to traditional parameters, such as wall thickening.

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