Variant angina

Variant angina, also known as Prinzmetal angina, vasospastic angina, angina inversa, coronary vessel spasm, or coronary artery vasospasm, is a syndrome typically consisting of angina (cardiac chest pain). Variant angina differs from stable angina in that it commonly occurs in individuals who are at rest or even asleep, whereas stable angina is generally triggered by exertion or intense exercise. Variant angina is caused by vasospasm, a narrowing of the coronary arteries due to contraction of the heart's smooth muscle tissue in the vessel walls. In comparison, stable angina is caused by the permanent occlusion of these vessels by atherosclerosis, which is the buildup of fatty plaque and hardening of the arteries.

In contrast to those with angina secondary to atherosclerosis, people with variant angina are generally younger and have fewer risk factors for coronary artery disease with the exception of smoking, which is a common and significant risk factor for both types of angina. Affected people usually have repeated episodes of unexplained (e.g., in the absence of exertion and occurring at sleep or in the early morning) chest pain, tightness in throat, chest pressure, light-headedness, excessive sweating, and/or reduced exercise tolerance that, unlike atherosclerosis-related angina, typically does not progress to myocardial infarction (heart attack). Unlike cases of atherosclerosis-related stable angina, these symptoms are often unrelated to exertion and occur in night or early morning. However, individuals with atherosclerosis-related unstable angina may similarly exhibit night to early morning hour symptoms that are unrelated to exertion.

Cardiac examination of individuals with variant angina is usually normal in the absence of current symptoms. Two-thirds of these individuals do have concurrent atherosclerosis of a major coronary artery, but this is often mild or not in proportion to the degree of their symptoms. Persons who have atherosclerosis-based occlusion that is ≥70% in a single coronary artery or that involves multiple coronary arteries are predisposed to develop a variant angina form that has a poorer prognosis than most other forms of this disorder. In these individuals but also in a small percentage of individuals without appreciable atherosclerosis of their coronary arteries, attacks of coronary artery spasm can have far more serious presentations such as fainting, shock, and cardiac arrest. Typically, these presentations reflect the development of a heart attack and/or a potentially lethal heart arrhythmia; they require immediate medical intervention as well as consideration for the presence of, and specific treatment regimens for, their disorder.

Variant angina should be suspected by a cardiologist when a) an individual's symptoms occur at rest or during sleep; b) an individual's symptoms occur in clusters; c) an individual with a history of angina does not develop angina during treadmill stress testing (variant angina is exercise tolerant); d) an individual with a history of angina shows no evidence of other forms of cardiac disease; and/or e) an individual without features of coronary artery atherosclerotic heart disease has a history of unexplained fainting.

Complaints of chest pain should be immediately checked for an abnormal electrocardiogram (ECG). ECG changes compatible but not indicative of variant angina include elevations rather than depressions of the ST segment or an elevated ST segment plus a widening of the R wave to create a single, broad QRS complex peak termed the "monophasic curve". Associated with these ECG changes, there may be small elevations in the blood levels of cardiac damage marker enzymes, especially during long attacks. Some individuals with otherwise typical variant angina may show depressions, rather than elevations in the ST segments of their ECGs during angina pain; they may also show new U waves on ECGs during angina attacks.

A significant percentage of those with variant angina have symptom-free episodes of coronary artery spasm. These episodes may be far more frequent than expected, cause myocardial ischemia (i.e. insufficient blood flow to portions of the heart), and be accompanied by potentially serious abnormalities in the rhythm of heart beats, i.e. arrhythmias. The only evidence of the presence of totally asymptomatic variant angina would be detection of diagnostic changes on fortuitously conducted ECGs.

The intake of certain agents have been reported to trigger an attack of variant angina. These agents include:

In addition, hyperventilation and virtually any stressful emotional or physical (e.g. cold exposure) event that is suspected of causing significant rises in the blood levels of catecholamines may trigger variant angina.