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.

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.

Inclusion Criteria:

• age from 18-85 years

Exclusion Criteria:

• patients with history of myocardial infarction or abnormal wall motion suggested by conventional echocardiography
• patients with acute heart failure, chronic heart failure or LVEF values less than 50%
• patients with congenital heart disease, severe valvular disease, severe bradycardia, high atrioventricular block and atrial fibrillation
• patients who did not store ultrasound images or whose ultrasound images were unclear
• patients who had incomplete clinical data

A total of 242 patients were enrolled, including 102 males (42.1%) and 140 females (57.9%). Their ages ranged from 44 to 81 years, with an average age of (62.6 + 8.3) years.