Ischemic heart disease is the leading cause of death in the United States¹ and angina pectoris is a common symptom of this disease.^2,3 "Angina" is used to describe clinical symptoms such as discomfort in the chest, jaw, shoulder, back, or arms that are induced by physical exertion or emotional stress and subside with rest or treatment with nitroglycerin.⁴ Some patients do not experience discomfort but complain of breathlessness or tire with activity. These symptoms are the result of underlying myocardial ischemia and are sometimes called anginal equivalents.

The American Heart Association (AHA) estimates that 6.8 million Americans suffer from angina and that 400 000 new patients present with stable angina each year.¹ Significantly more women have the condition than men, both in total numbers and as an age-adjusted percentage.¹ Angina limits normal daily activities; thus, it has a negative impact on quality of life (QOL). It has been shown that 1 year after coronary revascularization, roughly one third of patients with angina are not able to return to work.⁵ Not surprisingly, the societal impact and economic costs of angina are staggering. In the American College of Cardiology (ACC)/AHA 2002 Guideline Update for the Management of Patients with Chronic Stable Angina, Gibbons and colleagues state, "angina affects many millions of Americans with associated annual costs that are measured in tens of billions of dollars."⁴

Angina treatment involves a number of strategies.⁴ In general, the first step in angina management includes assessing patient risk factors, such as smoking, hypertension, dyslipidemia, diabetes mellitus, obesity, and physical inactivity. While alterations in these risk factors may improve symptoms and reduce cardiac events, the majority of patients with chronic stable angina require specific antianginal medications. It is recommended that beta-adrenergic blocking drugs be used as first-line therapy for patients with angina because these agents have been shown to have cardioprotective effects.⁴ Other standard therapies for chronic angina include calcium channel blocking agents and organic nitrates,⁴ but such medical therapy often does not provide adequate symptomatic relief. A number of novel therapies are directed at angina treatment, including new pharmacologic agents, gene therapy, enhanced external counterpulsation (EECP), spinal cord stimulation, and innovations in revascularization therapy. This article reviews the classification of angina pectoris and briefly describes standard and novel treatment strategies for this debilitating health problem.

Understanding Angina. Whereas there has been considerable research regarding angina, the exact mechanism of pain perception in patients with myocardial ischemia is still poorly understood. However, cardiac ischemic discomfort may be perceived in the heart, chest wall, arms, and back because of the close proximity of the spinal nerve receptors to these areas.⁶ Chest pain caused by myocardial ischemia is classified as stable or unstable angina.⁴ Patients with unstable angina have a much higher risk of acute cardiac events than patients with stable angina pectoris. Such risk can be further stratified as low, moderate, or high, depending on the frequency and severity of pain and on the presence of certain electrocardiographic abnormalities. Unstable angina is commonly described based on the way it presents. This includes new onset angina or angina that has increased in frequency and severity despite medical therapy, or angina that occurs at rest (Table 1). Angina is frequently defined using Canadian Cardiovascular Society (CCS) functional class (Table 2),⁷ a system that has been used for more than 3 decades. In 2002, a new CCS definition for grade IV angina was suggested that includes a set of detailed activities, "angina occurs while walking less than 1 block…or while walking in the house, or doing light chores or personal care" rather than the previous description: "Inability to carry on any physical activity without discomfort— anginal symptoms may be present at rest."⁸ While other grading systems have been defined, the CCS functional classification has been the most widely used by clinicians and investigators.