Variant angina is a form of
angina pectoris that shows transient ST-segment elevation on electrocardiogram during an attack of
chest pain. Ischemic episodes of variant angina show circadian variation and often occur at rest from midnight to early morning. Ischemic episodes also occur during mild exercise in the early morning. However, they are not usually induced by strenuous exercise in the afternoon. Other important clinical features of variant angina include the high frequency of asymptomatic ischemic episodes and the
syncope that sometimes occur during the ischemic episodes.
Syncope is due to severe arrhythmias, including
ventricular tachycardia,
ventricular fibrillation, and high-degree
atrioventricular block.
Coronary artery spasm is the mechanism of ischemic episodes in variant angina. The incidence of
coronary artery spasm shows a racial difference and is higher in Japanese than in Caucasians. Coronary arteriograms are normal or near-normal in most Japanese patients with variant angina. Deficient basal release of
nitric oxide (NO) due to endothelial dysfunction, and enhanced vascular smooth muscle contractility with the involvement of the Rho/
Rho-kinase pathway are reported to play important roles in the pathogenesis of
coronary artery spasm. Other precipitating factors of
coronary artery spasm include imbalance in autonomic nervous activity, increased oxidative stress, chronic low-grade
inflammation,
magnesium deficiency, and
genetic susceptibility. The genetic risk factors associated with
coronary artery spasm include gene polymorphisms of endothelial
NO synthase (NOS),
paraoxonase, and other genes.
Calcium channel blockers are extremely effective in preventing coronary
spasm. The long-acting
nitrate,
nicorandil, and
Rho-kinase inhibitor are also useful for inhibiting
coronary artery spasm. Because variant angina can lead to acute
myocardial infarction, fatal arrhythmias, and
sudden death, early treatment is important. The prognosis of patients with variant angina is favorable, if early complications can be overcome. However, because
coronary artery spasm cannot be suppressed in some patients, even with multiple medications, medications to suppress intractable
coronary artery spasm must be developed.