A total of 175 patients with chest pain, without wall motion abnormality and without significant coronary artery stenosis (<50%) assessed by coronary angiography or coronary computed tomography were enrolled from July 2011 to December 2017. Coronary flow reserve (CFR) of these patients were detected by transthoracic Doppler echocardiography. The patients were divided into coronary microvascular dysfunction group ( CFR≤2.5, n=67) and control group (CFR>2.5, n=108). At the same time, 67 age-matched patients with any major coronary arteries stenosis≥50% and without wall motion abnormality were involved into the obstructive coronary artery disease group. Parameters of global longitudinal strain (LS) and strain rate, subendocardial LS and subepicardial LS were quantified by 2D-STI, the differences of these parameters among three groups were analyzed，correlation analysis、univariate and multivariate analysis and receiver operating characteristic curve were used.
The study was designed to evaluate the left ventricular longitudinal strain and strain rate assessed by 2D-STI in patients with coronary microvascular dysfunction (CMD) or obstructive coronary artery disease (CAD) , to investigate the effect of different types of ischemic heart disease on the LV systolic function, and to explore the value of LS on the diagnosis of coronary microvascular dysfunction.