Microvascular angina is a condition where patients experience chest pain due to insufficient blood flow through the tiny blood vessels of the heart. It is often misdiagnosed as coronary artery disease and is treatable with a healthy lifestyle and medication. The causes are unknown, but risk factors include obesity, abnormal blood lipids, and hypertension. Diagnosis involves a series of tests, and treatment includes medication to relieve chest pain.
Microvascular angina is a condition similar to heart disease, called angina pectoris. Patients with microvascular angina also complain of chest pain, but the physician’s initial diagnosis is often coronary artery disease (CAD). Imaging studies, such as coronary angiography, would show that the heart is normal. While angina pectoris and other CADs are caused by inadequate blood flow through the coronary arteries, microvascular angina is due to insufficient flow through the microvasculature, or tiny blood vessels, of the heart. It is treatable with the right combination of healthy diet, regular exercise, and medications that dilate blood vessels.
Among patients who complain of chest pain and are subsequently evaluated by coronary angiography, about 20 to 30% have normal angiograms. In 1988, Cannon and Epstein coined the term microvascular angina for this combination of exertional chest pain and a completely normal angiogram, with or without electrocardiogram (ECG) changes on exercise testing. It’s also known as cardiac syndrome X, because its actual causes remain unknown.
Several pathophysiological mechanisms for severe chest pain have been proposed. The most important of these is myocardial ischemia, in which the function or anatomy of the coronary microvasculature is abnormal. There may be a decrease in the blood vessels ability to dilate or increase their diameter, leading to impaired blood supply, as well as nutrient and oxygen deprivation of the heart muscle. Another proposed mechanism is that the heart muscle suffers from metabolic imbalance, leading to a decrease in glucose uptake and utilization by the myocardium. Another proposed mechanism is that there is an increased sensitivity of pain receptors to stimuli from the heart.
Although the true causes of microvascular angina remain unidentified, several risk factors are known. These include abdominal obesity or excessive fat deposition in the abdomen, dyslipidemia or abnormal blood lipids, hypertension, glucose intolerance or insulin resistance, and pro-inflammatory states such as diabetes mellitus. Cardiac syndrome X is often associated with insulin resistance and central obesity, so it is sometimes called insulin resistance syndrome. People in the high-risk category include women, the elderly, and those who have a family member who has a history of heart disease.
When a person goes to the doctor complaining of severe chest pain, microvascular angina is not usually the initial diagnosis. A series of tests is needed before the doctor can tell that the patient’s condition is not esophageal spasm, angina pectoris, Prinzmetal’s angina, or heart attack. The usual tests done include treadmill or exercise electrocardiography testing, coronary angiography, and sometimes magnetic resonance imaging (MRI) of the heart.
Once microvascular angina has been diagnosed, the doctor prescribes drugs, such as dilatiazem and nifedipine, which are intended to relieve chest pain and improve the patient’s quality of life. Other alternatives include beta blockers such as carvedilol and propranolol, L-arginine, estrogen and aminophylline. Many of the risk factors for microvascular angina are avoidable, so it’s important to address them by eating a healthy diet, engaging in daily physical activity, and visiting your doctor regularly.
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