Chronic stable angina overview
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Overview
Angina pectoris, commonly known as angina is chest pain[1] due to ischemia (a lack of blood and hence oxygen supply) of the heart muscle, generally due to obstruction or spasm of the coronary arteries (the heart's blood vessels). Coronary artery disease or atherosclerosis of the coronary arteries is the most common cause of angina. The term derives from the Greek ankhon ("strangling") and the Latin pectus ("chest"), and can therefore be translated as "a strangling feeling in the chest". In angina pectoris the sensation of chest discomfort can be a feeling of tightness, heaviness, or pain.
Urgent Conditions that Chronic Angina Should be Distinguished From
Angina pectoris is a sign of coronary heart disease. If it occurs chronically this is called stable angina which is the topic of this chapter. If it occurs at rest or in an accelerating pattern this is called an acute coronary syndrome and can be a symptom of either:
- Unstable angina: An open artery with insufficient blood flow to the heart but without irreversible damage
- Non ST elevation MI: An open artery with insufficient blood flow to the heart with irreversible damage
- ST elevation MI: A closed artery with insufficient blood flow to the heart and irreversible damage
These conditions require urgent evaluation and treatment.
Pathophysiology
Most commonly, chronic stable angina is due to fixed obstructive disease or atherosclerosis which narrows the coronary arteries. This results in inadequate supply of blood and oxygen to meet the demands of myocardial metablosim. This supply / demand mismatch activates a molecular cascade of events that causes the release of molecules such as bradykinin and adenosine which in turn stimulate the sympathetic and vagal afferent fibers, causing the anginal pain. Certain conditions can increase the myocardial oxygen demand secondary to an increase cardiac output and can exacerbate chronic stable angina. These conditions include fever, thyrotoxicosis, anemia, emotional stress, and tachyarrythmias.
While fixed obstructive epicardial disease is the most common cause of chronic stable angina, vasospasm of the epicardial artery can also cause angina. Angina due to spasm of an epicardial artery is known as Prinzmetal's angina or variant angina. Chronic stable angina can also result from microvascular disease as well. This is known as microvascular angina or Syndrome X.
Clinical presentation: History and Physical Examination
The majority of patients present with a history of either chest pain or chest discomfort which may be typical (occurs in the epicardial region).
The presentation may also be atypical. For instance, some patients may present with dyspnea instead of chest pain and this is termed an angina equivalent.
History is extremely helpful and should include an assessment of risk factors as well. Physical examination may be normal or reveal findings of heart failure. Other findings to look for are peripheral vascular disease which is considered to be risk factor for CAD.
Calculating pretest probability for CAD
Pretest probability tells the probability of a target disorder before the result of the diagnostic test(s) are known. In case of angina, initial history and physical examination can help categorize the patient into low, intermediate or high probability group. This will then help in deciding the type of testing, interpreting result of the test and timing for starting the treatment.
Diagnostic tests
This includes lab tests like lipid profile, hemoglobin and hematocrit, blood glucose, TSH. ECG should be done but one shuld remember that it may be normal in majority of cases. Some findings to look for are evidence of active ischemia like ST-T wave depression, left ventricular hypertrophy, Q waves in multiple leads suggestive of old MI, bundle branch blocks, arrythmias. These findings will also help in choosing the next diagnostic test. Chest X-ray may be normal or show cardiomegaly or pulmonary vascular congestion. Specific cardiac tests for angina include exercise ECG testing, myocardial perfusion imaging, echocardiography, stress echocardiography and coronary angiography[2]. Choice of these tests is based largely on initial history and physical examination as well as resting ECG findings.
Treatment
Treatment for chronic stable angina includes lifestyle modification, pharmacotherapy and revascularization procedures(PCI, CABG). It is also important to identify any exacerbating factors like anemia, thyrotoxicosis, valvular heart disease or decompensated heart failure and treat them first, when possible. Smoking cessation counselling, diet and weight management, promoting physical exercise, BP and diabetes control are all part of risk factor modification and should be stressed at each clinic visit. Specific medical therapy includes antiplatelets(like ASA, clopidogrel), antianginals(like nitrates, beta blockers, calcium channel blockers, antilipid agents, ACE inhibitors and angiotensin receptor blocking agents. Coronary revascularization is recommended when optimal medical therapy has failed to reduce symptoms or severe atherosclerotic disease or high risk criteria on noninvasive testing[3]. Options available for revascularization are Percutaneous coronary interventionPCI and coronary artery bypass graftingCABG. In patients with chronic stable angina, the factors influencing the choice of coronary revascularization therapy (percutaneous coronary intervention or coronary artery bypass surgery) are varied and complex. The severity of symptoms, lifestyle, extent of objective ischemia, and underlying risks must be weighed against the benefits of revascularization and the patient’s preference, as well as local availability and expertise. Evidence from randomized trials and large revascularization registers can guide these decisions, but the past decade has seen rapid change in medical treatment, bypass surgery and percutaneous coronary intervention.
Prognosis and risk stratification
Ischemic heart disease remains number one cause of mortality in developed countries. Prognosis of stable angina varies widely depending on severity of symptoms, extent of atherosclerosis and presence of other risk factors and co-morbidities. For this reason, it is important to risk stratify every patient. This can be done with the help of history, physical exam and use of one or more of diagnostic tests like ECG, Echocardiography, exercise ECG testing, myocaridal perfusion imaging or coronary angiography<ref name="ACC">.
References
- ↑ "MerckMedicus : Dorland's Medical Dictionary". Retrieved 2009-01-09.
- ↑ ACC/AHA 2002 guideline update for the management of patients with chronic stable angina--summary article: a report of the American College of Cardiology/American Heart Association Task Force on practice guidelines (Committee on the Management of Patients With Chronic Stable Angina). Gibbons RJ, Abrams J, Chatterjee K, Daley J, Deedwania PC, Douglas JS, Ferguson TB Jr, Fihn SD, Fraker TD Jr, Gardin JM, O'Rourke RA, Pasternak RC, Williams SV; American College of Cardiology; American Heart Association Task Force on practice guidelines (Committee on the Management of Patients With Chronic Stable Angina). J Am Coll Cardiol. 2003 Jan 1;41(1):159-68. No abstract available. PMID: 12570960
- ↑ 2007 chronic angina focused update of the ACC/AHA 2002 guidelines for the management of patients with chronic stable angina: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines Writing Group to develop the focused update of the 2002 guidelines for the management of patients with chronic stable angina. Fraker TD Jr, Fihn SD; 2002 Chronic Stable Angina Writing Committee; American College of Cardiology; American Heart Association, Gibbons RJ, Abrams J, Chatterjee K, Daley J, Deedwania PC, Douglas JS, Ferguson TB Jr, Gardin JM, O'Rourke RA, Williams SV, Smith SC Jr, Jacobs AK, Adams CD, Anderson JL, Buller CE, Creager MA, Ettinger SM, Halperin JL, Hunt SA, Krumholz HM, Kushner FG, Lytle BW, Nishimura R, Page RL, Riegel B, Tarkington LG, Yancy CW. J Am Coll Cardiol. 2007 Dec 4;50(23):2264-74. No abstract available. Erratum in: J Am Coll Cardiol. 2007 Dec 4;50(23):e1. Pasternak, Richard C [removed]. PMID: 18061078