Ali Vasheghani-Farahani - Associate Professor, Department of Cardiology, Tehran Heart Center, Tehran University of Medical Sciences, Tehran, Iran
Nasrin Nouri - Medical Student, Student Scientific Research Center, Tehran University of Medical Sciences, Tehran, Iran
Soroush Seifirad - Research Fellow, Department of Cardiology, Children Medical Center, Tehran University of Medical Sciences, Tehran, Iran
Mahmood Sheikh Fathollahi - Assistant Professor, Department of Research, Tehran Heart Center, Tehran University of Medical Sciences, Tehran, Iran
Elham Hakki - Research Fellow, Department of Research, Tehran Heart Center, Tehran University of Medical Sciences, Tehran, Iran
Mohammad Alidoosti - Associate Professor, Department of Cardiology, Tehran Heart Center, Tehran University of Medical Sciences, Tehran, Iran
Gholamreza Davoodi - Associate Professor, Department of Cardiology, Tehran Heart Center, Tehran University of Medical Sciences, Tehran, Iran
Farzad Masoudkabir - Cardiology Fellow and Research Fellow, Department of Cardiology, Tehran Heart Center, AND Student Scientific Research Center (SSRC), Tehran University of Medical Sciences, Tehran, Iran
Hamidreza Poorhosseini - Associate Professor, Department of Cardiology, Tehran Heart Center, Tehran University of Medical Sciences, Tehran, Iran

BACKGROUND: This study was designed to compare the frequency of conventional cardiovascular disease risk factors and clinical biochemistry profile in patients with cardiac syndrome X (CSX) and obstructive coronary artery disease (CAD). METHODS: A cross-sectional study was conducted on patients with typical angina and positive exercise tolerance test undergoing coronary angiography in our center. ۳۴۲ consecutive patients with CSX were enrolled into this study and were matched regarding age and sex with ۳۴۲ patients with acute coronary syndrome (ACS) and also ۳۴۲ patients with chronic stable angina (SA). Cardiovascular risk factors as well as biochemistry profile of the patients were recorded. RESULTS: Mean age of the studied patients was ۵۳.۰ years and ۴۱.۵% were male. There was no significant difference between the CSX patients and CAD patients regarding body mass index (BMI). Frequency of diabetes mellitus, hyperlipidemia, smoking, family history of premature CAD and hypertension was significantly lower in patients with CSX than ACS and SA patients. Patients with CSX had significantly higher levels of high-density lipoprotein cholesterol (HDL-cholesterol) than comparators while the levels of low-density lipoprotein cholesterol (LDL-cholesterol), total cholesterol, triglyceride and fasting blood sugar (FBS) were significantly lower in patients with CSX than CAD patients. CONCLUSION: The present study demonstrated that CSX patients had substantially lower frequency of all conventional CVD risk factors than patients with obstructive CAD. This might aid in developing novel scoring systems or appropriateness criteria for angiographic evaluation of patients with typical angina and positive exercise test in order to reduce the rate of negative results.   Keywords: Cardiac Syndrome X, Microvascular Dysfunction, Coronary Artery Disease, Risk Factors