Effect of Ticagrelor on Adenosine-Induced Coronary Flow Reserve in Patients With Microvascular Angina

For inclusion in the study subjects should fulfill the following criteria:

1. Provision of informed consent prior to any study specific procedures
2. Female or male aged 18-80 years

3. A diagnosis of stable primary MVA based on the presence of

   • a history of typical effort angina,
   • exercise-induced ST-segment depression>1 mm,
   • normal or near-normal (coronary artery stenosis\<50%) coronary angiography,
   • absence vasospastic angina
   • a coronary flow reserve (CFR) \<2.5 in the left anterior descending coronary artery as assessed by coronary blood flow (CBF) response to adenosine at transthoracic Doppler echocardiography
   • suboptimal control of symptoms on conventional anti-ischemic therapy, as indicated by the occurrence of >1 episode per week of angina

Exclusion Criteria:

ubjects should not enter the study if any of the following exclusion criteria are fulfilled:

1. concomitance with any of the cardiac condition below

   • significant （>50%）coronary plaque disease
   • coronary artery spasm at angiography or other evidence of vasospastic angina
   • valvular or other structural heart disease
   • uncontrolled hypertension
   • abnormal echocardiographic examination including left ventricular hypertrophy
2. no previous consumption of the ticagrelor

3. no apparent contraindications to ticagrelor administration.

   • History of Intracranial Hemorrhage
   • Active Bleeding
   • Severe Hepatic Impairment: AST and ALT are greater than 3 times of the upper limit. Bilirubin is greater than the upper limit.
   • hypersensitivity (e.g. angioedema) to ticagrelor or any component of the product
   • severe COPD or asthma