To analyze the early systolic lengthening (ESL) of the left ventricular myocardium by two-dimensional speckle tracking imaging (2D-STI) in non-ST-segment elevation acute coronary syndrome (NSTE-ACS) patients who had no regional wall motion abnormality, and to explore the predictive value of global and territorial ESL for severe coronary artery stenosis.

A total of 171 NSTE-ACS patients without obvious regional wall motion abnormality who underwent echocardiography before coronary angiography at Beijing Chaoyang Hospital Affiliated to Capital Medical University from February to June 2019 were enrolled. According to the degree of coronary stenosis, there were 123 subjects in severe coronary artery stenosis group (≥70% diameter stenosis in at least one coronary artery) and 48 subjects in non-severe coronary stenosis group (<70% diameter narrowing in every coronary artery branch). Left ventricular myocardial global longitudinal strain (GLS), time to global early systolic lengthening (GEST), time to global post-systolic shorting (GPST) and territorial longitudinal strain (TLS), time to territorial early systolic lengthening (TEST), and time to territorial post-systolic shorting (TPST) were obtained by 2D-STI. The differences in the above parameters were compared between the two groups. Receiver operating characteristic (ROC) curve analysis was performed to assess the diagnostic efficacy of global and regional parameters for severe coronary artery stenosis by determining their area under the ROC curve (AUC) and cut-off values. A logistic regression model was established to determine the independent predictors of severe coronary stenosis in NSTE-ACS patients.

Compared with the non-severe coronary artery stenosis group, left ventricular GEST and GPST were significantly increased, while GLS was significantly decreased in NSTE-ACS patients with severe coronary artery stenosis (P<0.05 for all). In addition, both myocardial TEST and TPST were significantly increased in regions supplied by severely stenotic coronary arteries compared to non-severely stenotic coronary arteries (P<0.001 for both), while there was no statistically significant difference in left ventricular TLS between regions supplied by severely stenotic coronary arteries and non-severely stenotic coronary arteries (P=0.227). ROC curve analysis showed that myocardial GEST>8.9 ms yielded a specificity of 65% and sensitivity of 77%, and had the highest AUC (0.78) in predicting severe coronary stenosis, superior to GLS (AUC=0.62, P<0.05) and GPST (AUC=0.67, P<0.05). In addition, myocardial TEST could also distinguish regions related to severe coronary artery stenosis and non-severe arteries with moderate diagnostic accuracy (AUC=0.62, sensitivity 72%, specificity 51%). In multivariable logistic regression analysis, only left ventricular myocardial GEST remained an independent predictor of severe coronary artery stenosis in patients with NSTE-ACS.

In NSTE-ACS patients with severe coronary artery stenosis, left ventricular global and territorial systolic function are impaired, and particularly, both myocardial GEST and TEST are significantly increased. ESL parameters may be a reliable index for predicting severe coronary stenosis in NSTE-ACS patients without obvious regional wall motion abnormality.