The enigma of syndrome X

Area of Science:

• Cardiology
• Internal Medicine
• Diagnostic Imaging

Background:

• Syndrome X involves chest pain mimicking angina, normal epicardial coronary arteries on angiography, and ECG changes suggesting myocardial ischemia.
• The diagnostic criteria and underlying pathology of Syndrome X remain debated, contributing to literature confusion.
• While often attributed to small vessel disease, the exact cause of ischemia in Syndrome X is not definitively established.

Purpose of the Study:

• To clarify the diagnostic complexities and heterogeneous nature of Syndrome X.
• To explore potential underlying pathologies beyond epicardial coronary artery disease.
• To review the current understanding of Syndrome X, including its prognosis and diagnostic challenges.

Main Methods:

• Review of literature on Syndrome X, including coronary angiography, exercise testing, and myocardial biopsy findings.
• Analysis of studies investigating potential causes of ischemia in patients with Syndrome X.
• Evaluation of diagnostic criteria and their consistency across different patient cohorts.

Main Results:

• Syndrome X is characterized by chest pain, normal coronary arteries, and ECG abnormalities, but a positive exercise test is not always present.
• Coronary angiography may miss abnormalities in small vessels (<400 microns), while histology visualizes even smaller vessels (<150 microns).
• In some patients, ischemia is unlikely due to normal coronary sinus oxygen saturation during pacing-induced chest pain and ECG changes.

Conclusions:

• Syndrome X represents an inhomogeneous group of patients with diverse underlying pathologies causing similar symptoms.
• The diagnostic approach to Syndrome X requires careful consideration of multiple factors beyond epicardial coronary arteries.
• Further research is needed to elucidate the specific mechanisms and causes of chest pain in the varied presentations of Syndrome X.