NOTE: The term "Syndrome X" has also been used to describe the metabolic syndrome associated with obesity and diabetes mellitus.
Clinical features:
(1) presence of clinical angina, which may be typical or atypical
(2) most patients are women, often postmenopausal
Diagnostic features:
(1) normal angiography or mild disease insufficient to explain symptoms
(2) exercise testing positive
The primary differential diagnosis is occult coronary artery arteriosclerotic disease. Other conditions to consider are coronary artery microspasm and noncardiac chest pain.
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Clinical Finding
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Syndrome X
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Coronary Arteriosclerosis
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response to nitrates during exercise testing
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worsening in exercise tolerance
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improved exercise capacity
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electron beam CT
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very low score (see below)
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may show a low score but typically significantly higher
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response to rapid atrial pacing
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normal, with improved left ventricular function
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worsening in left ventricular function
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Chen et al (page 1529)used age-based cutoffs for calcification scores from electron beam CT:
(1) For a patient <= 60 years of age, a score equal to 0 was 80% sensitive and 90% specific for syndrome X.
(1) For a patient > 60 years of age, a score <=45 was 92% sensitive and 77% specific for syndrome X.
