Epidemiology of cardiac syndrome X and microvascular angina

Abstract

Chest pain and normal coronary angiography is seen in up 30 % of patients undergoing the investigation. Despite its notable prevalence, the epidemiology of the condition remains poorly documented. Since the turn of the twentieth century, researchers have been baffled by “unmistakable” angina in the absence of coronary artery disease. Curiosity as to the cardiac aetiology of this chest pain became the focus of several key studies investigating the clinical and haemodynamic features of patients with normal coronary angiography. From these early findings, the cardinal features of three specific disorders associated with normal coronary angiography were established – Cardiac Syndrome X, Microvascular Angina and more recently, the Coronary Slow Flow Phenomenon. Although ambiguity in the literature exists, it is likely that an ‘ischemic’ mechanism for the chest pain in these patients is explained by coronary microvascular dysfunction. It also now understood that despite the absence of significant coronary artery disease, the outcomes of patients are not entirely favourable, with studies suggesting a frequent persistence of chest pain, and increased risk of cardiac events, particularly among women. This chapter will review the available epidemiological data on patients with chest pain and normal coronary angiography, and the clinical features and possible aetiological explanations for the specific coronary microvascular disorders.