CAR-11. Syndrome X: a bit of a mystery.

Coronary artery disease is a leading cause of death worldwide. Over 1 million coronary angiograms are performed in North America annually, and a significant number are interpreted as normal. In the coronary artery surgery study registry of the 1970s, normal angiograms were found in 20% of patients. The prevalence of normal coronary angiograms has not changed in the current era of more sophisticated noninvasive testing, it is these sub-group of patients with positive stress test are classified as having cardiac syndrome X. The term Cardiac Syndrome X was first used in 1973 to describe a condition that still to this day remains a bit of a mystery. There is still no agreed definition of Cardiac Syndrome X, the diagnosis is generally made when angina-like chest pain, a positive response to stress testing and angiographically normal coronary arteries are present. In the medical literature, the term microvascular angina has been used interchangeably with the term syndrome X. The prevalence of Syndrome X is significantly higher among post-menopausal women than among men. More than 30 years after the initial publication, little more definitive information is known about this syndrome. It is now accepted as a heterogeneous clinical entity that is the product of genetic, coronary microvascular, metabolic, and clinical factors. Many theories have evolved through the years, including impaired coronary flow reserve, microvascular spasm, patchy prearteriolar vasoconstriction, disease of small arteries, pain due to excessive adenosine effect and estrogen deficiency. Both short and long-term prognosis of patients with Syndrome X are excellent. Yet, symptoms can be invalidating and refractory to conventional antianginal treatment with nitrates, beta-blockers and calcium-antagonists. Additional drugs which might be helpful in symptom control include: estrogens, adenosine antagonists (theophylline) and tricyclic antidepressants. We present two case reports of patients diagnosed with syndrome X treated with ACE inhibitor that showed dramatic symptomatic and clinical improvement, presumably due to improved coronary flow reserve due to increased nitric oxide bioavailability. The role of long-term ACE inhibitor treatment improved coronary microvascular function as well as myocardial ischemia in patients with syndrome X. Further studies are needed to evaluate the effects of long term ACE inhibitor treatment on clinical outcome.

Anil K. Goli, MD, Leeper Stephanie, MD, and Stephen A. Fahrig, MD. ETSU Heart, Johnson City, TN.