Risks associated with angina pectoris

Triggering events
 
 
 
 

What is angina pectoris? Angina Pectoris is recurring acute chest pain or discomfort resulting from decreased blood supply to the heart muscle(myocardial ischemia). Angina occurs when the heart’s need for oxygen increases beyond the level of oxygen available from the blood nourishing the heart (8). Angina is a common symptom for coronary heart disease (CHD)(9). The symptoms of angina include mild or severe pain, pressure, or discomfort in the chest, the pain is generally described as a feeling of a squeezing, strangling, heaviness, or suffocation sensation in the chest(8, 9).

What risks are associated with angina pectoris? Angina indicates that CHD is present and that some part of the heart is not receiving an adequate blood supply. Episodes of angina seldom cause permanent damage to the heart muscle. Angina pectoris is a temporary part of the heart muscle not getting enough blood, whereas a heart attack occurs when some part of the heart is suddenly and permanently cut off from the blood supply which causes permanent damage to the heart muscle (8). Patients who have already suffered a coronary heart disease (CHD) event such as angina pectoris are at considerably increased risk of recurrent fatal or non-fatal events compared with healthy individuals of the same age(1). Angina pectoris is thought to be a precursor to approximately 40 percent of acute coronary events (1).

What factors trigger an episode of angina pectoris?   There are several factors that trigger an episode of angina pectoris including emotional stress, extreme temperatures, heavy meals, alcohol, strenuous exercise, and cigarette smoking (8). Hypoglycemia and hyperglycemia induce angina pectoris.  Return to top

Types of Angina Pectoris Stable Angina Unstable Angina Prinzmetal’s or variant angina Microvascular angina        Return to top Stable Angina      Stable angina is a repeating pattern of chest pain which has not changed in character, frequency, intensity or duration for several weeks (2, 8). The level of activity or stress that provokes angina is predictable and the pattern changes slowly. Stable angina is the most common form and it appears gradually. These patients have an increased risk of a heart attack, but an episode of stable angina does not indicate that a heart attack is about to happen(8).      A crucial component of the management of the pain associated with angina pectoris is Identifying sources of stress and creating effective methods to minimize stress. Relaxation techniques to reduce stress include meditation, listening to music, prayer, and exercise(5).  The reasons for the benefits that emerge after a coronary patient implements relaxation techniques are not clear. However, important roles appear to be played by central neural transmitters, including serotonin, melatonin, epinephrine, and dopamine(5). Return to types of Angina Unstable Angina       Unstable angina is chest pain that is variable, either increasing in frequency or intensity and with irregular timing or duration. Unlike stable angina, unstable angina does not appear gradually, it first appears as a severe episode(8). An established stable angina might change suddenly or be provoked by less stress than in the past or an episode might suddenly occur while at rest. If the pattern of an episode changes, for example if a previous episode was only brought on during physical exertion, but an episode suddenly occurred at rest it is likely to be unstable angina(8). Return to types of Angina Prinzmetal's Angina Prinzmetal’s or variant angina is caused by a vasospasm, a spasm that narrows the coronary artery and lessens the blood flow to the heart(8). Prinzmetal's Angina usually occurs in arteries already narrowed by atherolsclerosis, in fact most people with it have severe coronary atherosclerosis in at least one major vessel(13). The spasm usually occurs very close to the blockage.Unlike stable and unstable angina, Prinzmetal's Angina usually occurs when  a person is at rest or sleep and not after physical exertion or emotional stress. It is associated with acute myocardial infarction, severe cardiac arrhythmias including ventricular tachycardia and fibrillation, and sudden cardiac death(13). Return to types of Angina Microvascular Angina  Microvascular angina, or Syndrome X, occurs when the patient experiences chest pain but has no apparent coronary artery blockage. This condition results from poor functioning of the tiny blood vessels that nourish the heart, arms and legs(8). Microvascular angina can occur during exercise or at rest. Reduced vasodilator capacity of the coronary microvessels is thought to be a cause of angina during exercise, but the mechanism of angina at rest is not known(12).  Coronary microvascular spasm and resultant myocardial ischemia may be the cause of chest pain in a subgroup of patients with microvascular angina(12).   Terminology Clarification          One major association between microvascular angina and the insulin-resistance syndrome has arisen from terminological confusion(14).  The term syndrome X was first used in the 1970’s to refer to a heterogeneous group of patients with chest pain and normal coronary angiograms. In the late 1980’s this concurrence of myocardial ischaemia and normal angiograms was called microvascular angina.  The term "metabolic" syndrome X was first used in the late 1980’s to describe a pathological insulin-resistant condition, characterised by high prevalences of non-insulin-dependent diabetes, hypertension, obesity, dyslipidaemia, and cardiovascular disease.  The term insulin resistance syndrome is now preferred by many to refer to this pathological insulin resistant condition (14). Diabetes and Angina     Insulin resistance and secondary hyperinsulinemia are recognized risk factors for development of atherosclerosis(14). Hyperinsulinemia (high insulin levels in the blood) is a marker for the Insulin Resistance Syndrome. Hyperinsulinemia results from the body’s attempt to overcome insulin resistance by secreting more insulin from the pancreas.     Insulin Resistance Syndrome has been demonstrated in patients with angina pectoris irrespective of detectable atherosclerosis at coronary angiograms. A study conducted by Botker et al provided clear evidence that patients with microvascular angina are insulin resistant, independent of body mass index and physical fitness(14).     Research by Fava et al indicated that diabetic patients with unstable angina have a higher mortality than non-diabetic patients (15). The presence of diabetes is a strong risk factor for coronary artery disease and cardiac death in elderly  hemodialysis patients (16). Both symptomatic and silent ischemic heart disease may occur frequently during hemodialysis because hemodialysis simultaneously reduces coronary artery oxygen delivery while increasing myocardial oxygen demand(17).   Return to types of Angina Return to top   Incidence The incidence of angina continuously rises with age in women while in men the incidence of angina peaks between 55 and 65 years of age before declining (3, 6, 7). Although angina pectoris is of great interest, there is a lack of data on a community wide basis because it is very difficult to study. Many cases are undetected and it is very likely that only a small fraction of cases reach specialist clinics (1). Return to top Diagnosis The diagnosis of angina pectoris usually involves a careful assessment and history of signs and symptoms (5). Diagnostic procedures to exclude angina or establish the severity of coronary heart disease include electrocardiogram (ECG or EKG), a stress test, and coronary arteriogram (or angiogram). The ECG records electrical impulses of the heart which enables one to assess if the heart muscle is not getting sufficient oxygen or if there are abnormal features of the heart(8). A stress test is used to detect coronary artery disease and to determine safe levels of exercise. In a coronary arteriogram (or angiogram), x-rays are taken after a contrast agent is injected into an artery to locate the narrowing, occlusions, and other abnormalities of specific arteries.  There are a few conditions which mimic angina. Sources of pain most often confused with cardiac pain are gastrointestinal (esophageal and hiatal hernia, biliary), musculoskeletal, pulmonary, and pericardial (5).  Return to top Prevention An analysis of data from NHANES III examined whether vitamins A, C, E and various carotenoids can protect against angina pectoris. None of the vitamins showed a significant association with angina, although the investigators found that serum concentrations of a-carotene, b-carotene, and b-cryptoxanthin were associated with a reduced odds of having angina (4). A population case control study  studied the relation between risk of angina pectoris and plasma concentrations of vitamins A,C, and E and carotene. Vitamin E was found to be  inversely related to the risk of angina (1, 10). Return to top Treatment Controlling the risk factors for angina pectoris, such as high blood pressure, cigarette smoking, high cholesterol levels, and excess weight is an essential part of treatment (8). The most common medication used to treat people with angina are nitrates (such as amyl nitrite or nitroglycerin) which help alleviate pain by widening the blood vessels, thereby allowing more blood flow to the heart muscle and decreasing the work load of the heart. Beta blockers are also commonly prescribed because they decrease the heart rate, blood pressure, and myocardial oxygen comsumption. Calcium channel blockers are also  prescribed because they cause the blood vessels to relax and allow blood to flow freely to the heart, lowering blood pressure and relieving anginal pain(11). Surgery (coronary artery bypass) or angioplasty might be necessary forms of treatment if there is significant narrowing of the coronary arteries. A coronary artery bypass is a procedure that splices healthy blood vessels taken from elsewhere in the body to the affected coronary arteries so that the clogged areas are bypassed(11). Return to top

Links about Angina Pectoris http://www.viahealth.org/disease/cardiac/anginap.htm http://www.americanheart.org/Heart_and_Stroke_A_Z_Guide/angina.html http://www.medwebplus.com/subject/Angina_Pectoris? http://cardiology.medscape.com/PCI/angina/public/angina-about.html http://www.medinfo.co.uk/conditions/angina.html

Department of Biometry and Epidemiology- Medical University of South Carolina                            Biometry 737: Cardiovascular Epidemiology- Professor: Daniel Lackland,  Ph.D.                                                 Spring 2001 - Page Author: Katharine McGreevy