Coronary microvascular disease, also known as cardiac syndrome X, is a type of heart disease. The heart is a muscle that requires nutrients and oxygen, which is supplied by blood that travels through tubes or vessels called the “coronary arteries.” When these tubes become damaged or clogged, a patient can develop coronary artery disease. Coronary artery disease (CAD) can ultimately cause a blockage of blood flow in the heart and a heart attack. Coronary microvascular disease is a type of CAD characterized by damage to the smaller coronary blood vessels, which may potentially spasm and decrease blood flow to the heart. Coronary microvascular disease commonly develops in women, especially young women. The most common symptom of coronary microvascular disease is angina, or chest pain, that lasts longer than 10 minutes and even longer than 30 minutes. Fatigue, problems sleeping and shortness of breath are also symptoms. Symptoms are usually noticed during routine activities and times of mental stress. There is no specific test for coronary microvascular disease, but stress tests and imaging are often used. Mediations such as aspirin and beta blockers are the main treatment for coronary microvascular disease.