A physician might suspect cardiac syndrome X in patients who suffer from prolonged bouts of chest pain (angina), sometimes as long as 10 minutes. These bouts of chest pain may occur after exercise or at rest. They may or may not respond to nitrates. From there, the diagnosis of cardiac syndrome X is a matter of ruling out coronary artery disease and other non-cardiac causes of the chest pain.

Typically, tests will be ordered, often beginning with an electrocardiogram (EKG) or exercise stress test. These tests may, or may not, have abnormal results.

The essential test to diagnose cardiac syndrome X is the cardiac catheterization test, including a coronary angiogram. A cardiac catheterization is used to examine the interior of the coronary arteries by inserting a catheter into a blood vessel in the body (usually in the groin) and advancing it to the heart. In CAD patients, the test reveals blockage of an artery that interferes with blood flow to the heart. Syndrome X patients, however, have no evidence of narrowing or blockage at cardiac catheterization. In general, a positive exercise stress test and a normal cardiac catheterization can confirm the diagnosis of Cardiac Syndrome X.

One new diagnostic approach is a 64 multislice CT scan, which utilizes a non-invasive approach to visualize the coronary artery. This test is very sensitive and reliable when the coronary arteries have no calcification present to interfere with the scan. However, 64-slice CT scanners are relatively rare and the coronary angiogram remains the gold standard test.

As part of the diagnostic approach, the following factors (which are associated with angina or chest discomfort and normal coronary arteries) are usually ruled out as causes or contributors before a diagnosis of cardiac syndrome X is made:

• High blood pressure (hypertension).
  
  
• Left ventricular hypertrophy. An increase in the size of the left ventricle due to growth of muscle tissue.
  
  
• Valvular heart disease. Any dysfunction or abnormality in one or more of the heart’s four valves.
  
  
• Esophageal spasm. An involuntary and abnormal contraction of the muscle fibers of the esophagus (the passageway from the throat to the stomach).