Cardiac syndrome X
|Cardiac syndrome X|
|Classification and external resources|
Cardiac syndrome X is angina (chest pain) with signs associated with decreased blood flow to heart tissue but with normal coronary arteries. Cardiac syndrome X is sometimes referred to as 'microvascular angina' when there are findings of microvascular dysfunction.
Some studies have found increased risk of other vasospastic disorders in cardiac syndrome X patients, such as migraine and Raynaud's phenomenon. It is treated with beta-blockers, such as metoprolol, and usually carries a favorable prognosis.
This is a distinct diagnosis from Prinzmetal's angina.
Signs and symptoms
While there is no formal definition for cardiac syndrome X, the general consensus is that it entails all of the following:
- Angina: This usually does not cause dysfunction on echocardiogram and can last longer than that of heart disease.
- Abnormal cardiac stress test: ST changes are typically similar to those of coronary artery disease, and the opposite of those of Prinzmetal's angina. Myocardial perfusion imaging can be abnormal in 30% of patients.
- Coronary angiogram: Normal
- Other causes of chest pain must be ruled out, including:
The is no specific known cause for syndrome X, but rather a multitude of risk factors that act together. It is believed that the lack of blood flow caused by a microvascular disease and enhanced pain perception are two of the factors that may cause it. The microvascular dysfunctions refer to the abnormalities in the very small blood vessels of the heart. The narrowing of these vessels may lead to lack of oxygen in specific areas of the cardiac muscle causing chest pain. Several studies have shown that patients suffering from syndrome X have enhanced pain perception, and usually feel more intense chest pain than individuals without syndrome X.
The risk factors include abdominal obesity, meaning excessive fat tissue in and around the abdomen, atherogenic dyslipidemia which is a blood fat disorder, and elevated blood pressure. Other risk factors are insulin resistance or intolerance to glucose, prothrombotic state or proinflammatory state. Older people are more at risk to develop this condition, and there is some evidence that suggests that there are genetic mutations that predispose to the syndrome. Women are more prone to this condition than men, as well as those who have a history of heart disease in the family.
In a large percentage of patients, there is a finding of systemic microvascular abnormalities, causing reduced blood flow in the microvasculature of the cardiac muscles.
While numerous physiological mechanisms have been proposed, none have been proven.
Cardiac syndrome X is a diagnosis of exclusion. Typically this will necessitate both a clinical diagnosis, appropriate stress testing, and a coronary Angiogram that meet the above criteria. Cardiac MRI can be used to diagnose cardiac syndrome X. Studies are ongoing to validate this approach.
Cardiac syndrome X can be diagnosed using different tests and exams, but it is mainly a diagnosis of exclusion. However, sedentary and overweight individuals with a family history of type 2 diabetes should be tested regularly to determine whether they have irregular levels of glucose or lipids, or blood pressure abnormalities, factors which are usually associated with cardiac syndrome X. A first test to be taken is an exercise stress test which shows if the heart is not getting blood during exertion. Angiograms may be useful and conclusive when diagnosing cardiac syndrome X because they offer a detailed image of the heart. However, they cannot detect potential abnormalities in the small arteries, and the doctor may ask for more tests in order to rule out other heart conditions, such as Prinzmetal's angina which has similar symptoms.
Chest pain caused by cardiac syndrome X is most of the time unpredictable and it can occur when at rest and/or during exercise. The pain associated with syndrome X is normally more intense and it lasts for longer periods of time compared to pain caused by other conditions. For example, a stable angina causes chest pain that goes away when at rest. Another difference is that while chest pain caused by any type of stable angina is relieved with nitroglycerin, this drug is not effective in most of patients with Syndrome X.
The reasons why women are more prone than men to develop a syndrome X condition are still not clear. However, it is believed that hormones along with other risk factors unique to women play a very important role. The constant changing of the estrogen levels may be one of the reasons along with the changes brought by birth.
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- calcium channel blockers - specifically nifedipine and diltiazem can be effective.
- beta blockers - also work.
- aminophylline - may work by inhibiting adenosine receptors.
- estrogen - may work in women.
- L-Arginine - increases release of NO at vascular level, thus leading to vasodilatory effect
- Ranolazine - shown to improve angina and myocardial ischemia
Even if it is a serious medical condition, cardiac syndrome X is an incurable disease which seldom causes a heart attack or puts the life of the patient at risk. The treatment consists of drugs, mainly to relieve chest pain, but a very important part of the treatment is regularly visiting the doctor and repeating the tests to make sure the condition was taken care of in full.
The first step in managing cardiac syndrome X is the administration of nitrates which relieve the chest pain. They are used because of their ability to relax the muscles of the heart and blood vessels. However, they prove to be inefficient in as many as half of patients. Alternative treatments may consist of calcium channel blockers or beta blockers which reduce chest pain by relaxing the muscle cells lining the artery and improving blood flow to the heart while lowering blood pressure. Aminophylline may also work, while estrogen can be effective in women.
Also, a change in lifestyle is highly recommended in order to cure and to prevent syndrome X. Patients should start following healthier diets which are low in saturated fats, and should participate in regular physical activities. However, any patient with a heart disease condition should first seek for a medical opinion before starting exercising. Quitting smoking is also highly recommended.
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- Cardiac Syndrome Details Archived January 9, 2010, at the Wayback Machine. Retrieved on 2010-02-02
- Heart Disease Conditions Diagnose Me Online Portal. Retrieved on 2010-02-02
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- Cardiac Syndrome X
- Texas Heart Institute
- New England Journal of Medicine Editorials