[Microvascular angina and syndrome X].
Cardiac syndrome X defines patients with typical chest pain, transient ischaemic ST segment changes during effort and normal coronary angiograms. An ischaemic origin has been postulated for syndrome X since its description over 30 years ago. This has been based on the fact that patients with cardiac syndrome X have abnormal perfusion scans, a drop in both pH and oxygen saturation of the coronary sinus blood during chest pain and transmyocardial lactate production during stress testing. Moreover, nuclear magnetic resonance spectroscopy studies, demonstrated transient myocardial ischaemia in 20% of women with syndrome X. Microvascular endothelial dysfunction appears to be responsible for at least some of the abnormalities detected in the coronary circulation of patients with syndrome X ("microvascular angina"). ET-1, a potent vasoconstrictor, is synthesised by endothelial cells and may be responsible for coronary flow abnormalities in microvascular angina. Plasma levels of ET-1 are significantly raised in patients with syndrome X, compared to normal controls and a significant relationship has been found between baseline ET levels and abnormal coronary vascular responses in patients with syndrome X. Several investigators, however, have questioned the existence of myocardial ischaemia in patients with cardiac syndrome X. Their arguments are mainly based on the fact that prognosis is good in these patients and that studies with stress echocardiography have consistently failed to show regional wall motion abnormalities, even in patients with typical ischaemic ECG changes. Controversy exists as to the causes of syndrome X and this article reviews the evidence in relation to myocardial ischaemia as a pathogenic mechanism in this syndrome.
Kaski
Juan Carlos
JC
Coronary Artery Disease Research Unit, Cardiological Sciences, St. George's Hospital Medical School, London, United Kingdom. jkaski@sghms.ac.uk
Pérez Fernández
Ruth
R
D016232:Endothelins / Q000502:physiology; D006801:Humans; D017566:Microvascular Angina / Q000150:complications / Q000209:etiology; D017202:Myocardial Ischemia / Q000150:complications
D016232:Endothelins