Microvascular Assessment of Ranolazine in Non-Obstructive Atherosclerosis (MARINA)

The purpose of this study is to look at the effects of the drug Ranolazine compared to Placebo on symptoms of chest pain or chest tightness (known as angina), exercise endurance and ability, and changes in blood flow to the very small arteries of the heart (known as coronary microvascular function) in patients who do not have significant blockages in their major heart arteries. Ranolazine is a drug that is already approved by the FDA for angina, but it may be particularly effective in people with disease in their tiny heart vessels (known as coronary microvascular disease). This trial aims to enroll 50 patients with angina who undergo baseline bicycle exercise testing with monitoring of the heart's electrical activity and oxygen consumption (known as cardiopulmonary exercise test) and coronary angiogram (taking pictures of the heart arteries through small hollow tubes placed through the wrist or groin). If severe blockages in the main arteries are not found then testing for coronary microvascular function will be performed. Subsequently, participants will then be randomized 50/50 to either Ranolazine or Placebo. After taking the study drug for 12 weeks, they will then repeat the cardiopulmonary exercise test and the coronary angiogram with testing for microvascular function.