Cardiac Syndrome X Workup

Updated: Dec 24, 2020
  • Author: Subodh R Devabhaktuni, MD; Chief Editor: Richard A Lange, MD, MBA  more...
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Workup

Approach Considerations

Along with routine laboratory studies in patients with suspected cardiac syndrome X (CSX), tests for cholesterol levels and inflammatory markers should be considered.

Levels of vitamin D may be considered as clinically warranted. Vitamin D deficiency may be a risk factor, potentially related to increased inflammation leading to the development of endothelial dysfunction and microvascular angina. Levels of serum vitamin D in patients with cardiac syndrome X appear to be significantly lower than those who don't have this condition. [42]

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Imaging Studies

Electrocardiography

The resting electrocardiography (ECG) findings may be normal, but nonspecific ST-T–wave abnormalities are often observed, sometimes in association with the chest pain. Approximately 20% of patients with cardiac syndrome X (CSX) have positive results on exercise tests. However, many patients with this syndrome do not complete the exercise test because of fatigue or mild chest discomfort. Left ventricular function is usually normal at rest and during stress, unlike in obstructive coronary artery disease, in which function often becomes impaired during stress.

Heart rate variability appears to be associated with exercise capacity in patients with cardiac syndrome X, particularly in young individuals. [43]

Other imaging modalities

Multislice spiral computed tomography (CT) coronary angiography, positron emission tomography (PET) scanning, and cardiovascular magnetic resonance imaging (CMRI) may become part of the diagnostic algorithm in future.

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Procedures

The criterion standard test to evaluate endothelial function is an invasive determination of coronary flow reserve via Doppler guidewire in the cardiac catheterization laboratory (ie, quantifying the coronary blood flow in response to nitroglycerine and acetylcholine infusion) (see image below).

Cardiac Syndrome X. Coronary blood flow in response Cardiac Syndrome X. Coronary blood flow in response to nitroglycerine (NTG) and acetylcholine (ACH) infusion.

Although evidence of myocardial ischemia secondary to abnormal coronary reactivity testing can be detected noninvasively via single photon emission computed tomography, positron emission testing, and stress cardiac magnetic resonance imaging (see image below), the sensitivity and specificity of these measures remain incompletely characterized. [37]

Cardiac Syndrome X. Cardiac magnetic resonance ima Cardiac Syndrome X. Cardiac magnetic resonance image.
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