AbstractWe sometimes encounter patients with microvascular angina (MVA), a disease characterized by anginal pain without abnormal coronary arteriographic findings or coronary spasm. More than 40 years have passed since MVA was first confirmed. The terms ‘syndrome X’, ‘cardiac syndrome X’ and ‘microvascular dysfunction’ have also been used to describe conditions similar to MVA, but all with slightly different definitions. The cause of MVA seems almost certain to be organic and functional abnormalities of the small arteries of the heart. Patients with MVA are likely to suffer from endothelial dysfunction and other microvascular abnormalities of both the coronary and peripheral arteries. The major treatment of MVA has been medication, most often calcium channel blockers. The prognosis of MVA is generally excellent, although symptoms remain in many studies. Some MVA patients with accompanying hypertensive heart disease have gone on to develop progressive left ventricular dysfunction, with poor prognosis. The different definitions applied to the terms used to describe this condition, what we refer to here as MVA, can confound issues involved in diagnosis, prognosis and proper treatment. Therefore, it is extremely important to distinguish primary MVA without underlying heart disease from secondary MVA to explore the disease mechanism and examine the clinical characteristics. It is more than 40 years since Likoff first confirmed this disease; therefore, all researchers know that strict diagnostic criteria for MVA should be immediately established.