Cardiac Syndrome X and Microvascular Angina

Abstract

Chest pain suggestive of myocardial ischemia occurs in approximately 20–30% of patients in the absence of angiographically obvious coronary artery disease, as suggested by findings in large studies [1 –3]. The presence of angina-like chest pain in subjects with normal coronary arteriograms is often referred to as “syndrome X”. The term “syndrome X” was used for the first time by Kemp [4] in 1973 in an editorial comment of a paper by Arbogast and Bourassa [5] who compared the effects of atrial pacing on the left ventricular function of patients with coronary artery disease and patients with normal coronary arteriograms (termed “group X”). Arbogast and Bourassa were puzzled by the observation that patients of “group X” had normal ventricular performance despite the occurrence of typical ischemic electrocardiographic changes and metabolic evidence of ischemia, such as myocardial lactate production. In his editorial article, over 25 years ago, Kemp [4] highlighted several important aspects of the syndrome. In particular, the heterogenous nature of syndrome X, the possibility of more than one etiologic cause and the fact that a different form of myocardial ischemia could play a pathogenic role in this condition.