Angina is broadly defined as an imbalance between oxygen supply to oxygen demand in the heart, leading to a clinical syndrome characterized by precordial discomfort or pressure, typically precipitated by exertion and relieved by rest or sublingual nitroglycerin. The cause is usually critical coronary artery obstruction due to atherosclerosis, though vasospasm of a coronary artery may underlie it. The pain is usually described as "viselike", "constricting", "crushing", "heavy" and "squeezing".
There are three primary types of angina, the management of which depends on proper identification.
Stable angina – also referred to as angina of effort, fixed angina, classic angina or typical angina – is characterized by the appearance of chest pain as a result of physical exertion, emotion, cold or eating. It is generally caused by advanced coronary atherosclerosis.
Vasospastic angina, also referred to as variant angina or Prinzmetal's angina, is not necessarily associated with activity and pain, and can develop with the patient at rest. This type of angina is usually caused by a spasm in the coronary artery, which may or may not be associated with the concomitant presence of advanced atherosclerosis.
Unstable angina is thought to be caused primarily by the formation of platelet thrombi in the coronary vessels, especially in atherosclerotic vessels. As the name suggests, this form of angina is highly unstable and frequently precedes the development of myocardial infarction.
Management of angina should start with the correction of cardiovascular risk factors, the correction of lifestyle, various pharmacological approaches, revascularization, and more recently (and experimentally) gene therapy.
Pharmacological management revolves around several goals: dilate the coronary arteries (increase oxygen supply), decrease heart rate or contractility (decrease oxygen demand), decrease afterload (decrease oxygen demand), or decrease preload (decrease oxygen demand). With unstable angina, another aim is preventing the formation of thrombi in the coronary arteries by the use of antithrombotic drugs.
Therefore, drugs used for the management of angina can be broken down into those which inhibit myocardial oxygen demand, such as nitrates, beta blockers, calcium channel blockers, and ACE inhibitors; drugs which increase coronary flow such as calcium channel blockers, nitrates and ACE inhibitors; and antithrombotic agents such as aspirin and glycoprotein antagonists.