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Angina pectoris and normal coronary arteries: cardiac syndrome X
  1. Filippo Crea,
  2. Gaetano A Lanza
  1. Istituto di Cardiologia, Università Cattolica del Sacro Cuore, Roma, Italy
  1. Correspondence to:
    Professor Filippo Crea
    Istituto di Cardiologia, Università Cattolica del Sacro Cuore, Largo A. Gemelli, 8, 00168 Roma, Italy;

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Among patients undergoing coronary angiography because of angina typical enough to suggest coronary artery disease, 10–30% are found to have “normal” or “near normal” epicardial coronary arteries at angiography.

A group of these patients presents features of “cardiac syndrome X”, which is typically characterised by:

  • predominantly effort induced angina

  • ST segment depression suggestive of myocardial ischaemia during spontaneous or provoked angina

  • normal coronary arteries at angiography

  • absence of spontaneous or provoked epicardial coronary artery spasm

  • absence of cardiac (for example, hypertrophic or dilated cardiomyopathy) or systemic (for example, hypertension, diabetes) diseases potentially associated with microvascular dysfunction.

However, several groups of patients presenting with angina pectoris and normal coronary arteries do not fall into the strict definition of syndrome X, including those with predominant rest angina, those with hypertension or diabetes, or those with lack of ischaemic-like ECG changes during angina. It is still largely unknown whether the pathogenesis of angina in these various subsets of patients is different from that of angina in patients with typical syndrome X. Nevertheless, patients with typical and non-typical syndrome X have frequently been pooled together, thus making comparisons among different studies rather problematic. Therefore, a consensus document on the definition, classification, and management of patients with angina and normal coronary arteries would be very useful.


Syndrome X is characterised by two major abnormalities, which may combine variously to determine the individual clinical picture: (1) coronary microvascular dysfunction; and (2) abnormal cardiac pain sensitivity.

Microvascular dysfunction

Since its first description it was suggested that, in syndrome X, angina is caused by myocardial ischaemia determined by a dysfunction of small resistance coronary artery vessels (< 500 μm) not visible at coronary angiography, a condition defined as “microvascular angina”.1

The occurrence of myocardial ischaemia in these patients is indicated by transient ST segment depression and reversible perfusion defects …

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