Heart or Mind? Unexplained Chest Pain in Patients with and Without Coronary Disease

Abstract

Patients with unexplained chest pain continue to present a difficult challenge for clinicians, especially for cardiologists. Approximately 20% of patients undergoing diagnostic coronary arteriography for acute or chronic cardiac ischemia have angiographically normal coronary arteries. In these cases, patients with chest pain are usually reassured by their physician and other causes of substernal chest pain are searched. However, apart from a sizeable proportion of patients with gastroesophageal disorders, the remaining patients remain symptomatic without apparent reasons. The mechanism behind this phenomenon is likely to be the result of a combination of functional or anatomical abnormalities in the coronary microcirculation, a metabolic disorder which affects the handling of energy substrates by the heart, insulin resistance and neuropsychological components affecting pain perception. These patients often exhibit an increase in sympathetic outflow to the cardiovascular system, which might account for the reduction in coronary flow reserve, changes in metabolic utilization and development of insulin resistance that are seen in some of these patients. Therapeutically, beta-blockers appear to be most effective in controlling the symptoms associated with this condition, although those calcium antagonists which do not affect the neurohormonal system may be of some utility in patients with primary microvascular angina, in which microvascular spasm is operating or in whom excessive constriction of the distal component of the coronary circulation limits the vasodilatory reserve. This article reviews the clinical presentation, differential diagnosis, and approach to evaluation and therapy of this complex group of patients.