Syndrome X: Pathophysiology and clinical management

The term 'syndrome X' is now widely used to specify a group of patients with anginal chest pain, ischemia-like electrocardiogram, normal coronary angiograms, and no evidence of coronary spasm. Though chest pain and exercise-induced myocardial ischemia may both be present in patients with syndrome X and those with coronary artery disease, the underlying pathogenesis of these two disease entities is different. In patients with syndrome X, the causes of angina and myocardial ischemia are multifarious while coronary angiograms are normal. Coronary microvascular function has been shown to be impaired in these patients. However, the presentation of myocardial ischemia may be varied and even subclinical, suggesting dynamic characteristics and regional distribution of coronary microvascular insufficiency in them. Recently, there is increasing evidence that chest pain may develop without detectable myocardial ischemia and has been attributed to abnormal pain perception in at least some of the patients. Thus, there is a heterogeneous group of patients with syndrome X. The rational patient management should be related to individual clinical presentation and depend upon the proper identification of the underlying mechanisms of anginal chest pain or myocardial ischemia or both in these patients.