Objective To investigate the value of three-dimensional strain imaging（3D-STI）in evaluating left ventricular myocardial mechanics in non-ST-segment elevation myocardial infarction（NSTEMI）patients without regional wall motion abnormality（RWMA）.Methods Thirty-eight NSTEMI patients without RWMA detected by routine ultrasonography were selected as the case group

and thirty healthy subjects with matched age and sex were enrolled as the control group.Echocardiography

blood myocardial enzymes examination and blood biochemical testing were performed on two groups. The left ventricular end-diastolic diameter（LVED）

the left ventricular fractional shortening（FS）

the left ventricular ejection fraction（LVEF）and the stroke volume（SV）were measured. And the global longitudinal peak systolic strain（GLS）

the global radial peak systolic strain（GRS）

the global circumferential peak systolic strain（GCS）and the global area peak systolic strain（GAS）were obtained by 3D-STI. The correlation between myocardial strain parameters and clinical data

laboratory indexes were analyzed. ROC curve was drawn to analyze the diagnostic efficacy of myocardial strain parameters in myocardial infarction.Results There were no significant differences in age

blood pressure

blood lipids

blood glucose

blood creatinine

blood uric acid

blood CK-MB and NT-proBN between the two groups. Compared with control group

the GAS in case group was reduced[（-31.27±1.87）% vs.（-42.02±1.26）%

t=17.02

P=0.000]

and the blood hs-CTnI was increased[（2.11±1.78）% vs.（0.07±0.01）%

t=6.25

P=0.000]

but there were no significant differences in GLS

GRS

GCS

LVED

FS

LVEF and SV.Correlation analysis showed that there were positively correlation between GAS and LVEF

FS

hs-CTnI（r= 0.45

0.25

0.61

all P<0.05）. ROC curve showed that the sensitivity of evaluating NSTEMI was 92.1% and the specificity was 80% according to the absolute value of GAS<18.15%

and the area under the curve was 0.91.Conclusion 3D-STI can quantitatively analyze the mechanical changes of left ventricular myocardium in NSTEMI patients

it can provide a non-invasive and simple new method for clinical evaluation of NSTEMI.