Objective:To investigate the effect and relationship of coronary microvascular dysfunction (CMD) on cardiac mechanical indices in patients with non-obstructive coronary artery disease(NOCAD) in the resting state.Methods:This study was a single-center retrospective study. Seventy-nine NOCAD patients who hospitalized in Qilu Hospital of Shandong University from July 2017 to March 2022 were recruited. All patients underwent conventional echocardiography examination and the examination of coronary flow velocity reserved by transthoracic Doppler echocardiography (TTDE-CFVR). Based on the results of TTDE-CFVR, patients were divided into CMD group (CFVR<2.5, 32 cases) and a control group (CFVR≥2.5, 47 cases). Clinical data, routine echocardiographic parameters, regional mechanical indices including regional myocardial work index(RWI) and regional longitudinal strain(RLS), global mechanical indices including left ventricular global longitudinal strain(GLS), global longitudinal strain in the endocardial layer(GLS-endo), global longitudinal strain in the epicardial layer(GLS-epi), left ventricular global work index(GWI), global contractive work(GCW), global waste work(GWW), global work efficiency(GWE) were compared between two groups. Binary logistic regression was used to analyze the risk factors of CMD. ROC curve was used to construct a prediction model for CMD.Results:There was no significant difference in sex ratio, BMI, smoking history, diabetes, hypertension and dyslipidemia between CMD group and control group. Age was significantly higher in the CMD group than in the control group. RWI, GWI, GCW, GWE and the absolute values of RLS, GLS, GLS-endo and GLS-epi were significantly lower in the CMD group than in the control group. Logistic regression analysis showed that the decrease of absolute value of GLS was an independent risk factor for the CMD( OR=1.335, 95% CI=1.041-1.713, P=0.023). ROC curve showed that myocardial strain-related indexes had a good decrease value for the CMD. Conclusions:For patients with NOCAD, the presence of CMD is associated with the decrease of left ventricular regional and global systolic function.