Coronary heart disease (CHD), sometimes described as coronary artery disease (CAD) or ischaemic heart disease (IHD), is a condition in which the vascular supply to the heart is impeded by atheroma, thrombosis or spasm of coronary arteries.
This may impair the supply of oxygenated blood to cardiac tissue sufficiently to cause myocardial ischemia which, if severe or prolonged, may cause the death of cardiac muscle cells. Similarities in the development of atheromatous plaques in other vasculature, in particular, the carotid arteries, with the resultant cerebral ischemia has resulted in the term cardiovascular disease (CVD) being adopted to incorporate CHD, cerebrovascular disease and peripheral vascular disease.
Almost 200,000 people die from CVD in the UK each year with CHD accounting for almost a half of these. About 30% of premature deaths (below 75 years old) in men and 22% of premature deaths in women result from CVD.
About 3.5% of UK adults have symptomatic CHD. One-third of men aged 50–59 years of age have evidence of CHD, and this proportion increases with age. In the UK, there are about 1.3 million people who have survived a myocardial infarction and about 2 million who have or have had, angina and this equates to about 5% of men and 3% of women. Approximately 260,000 people suffer a myocardial infarction in any year, of whom 40–50% die.
Traditionally, the main potentially modifiable risk factors for CHD have been considered to be hypertension, cigarette smoking, raised serum cholesterol and diabetes. More recently psychological stress and abdominal obesity have gained increased prominence.
Patients with a combination of all these risk factors are at risk of suffering a myocardial infarction some 500 times greater than individuals without any of the risk factors.
Stopping smoking, moderating alcohol intake, regular exercise and consumption of fresh fruit and vegetables were associated independently and additively with the reduction in the risk of having a myocardial infarction.
Diabetes mellitus is a positive risk factor for CHD in developed countries with high levels of CHD, but it is not a risk factor in countries with little CHD.
Signs and Symptoms
The primary clinical manifestation of CHD is chest pain. Chest pain arising from stable coronary atheromatous disease leads to stable angina and normally arises when narrowing of the coronary artery lumen exceeds 50% of the original luminal diameter. Stable angina is characterized by chest pain and breathlessness on exertion; symptoms are relieved promptly by rest. A stable coronary atheromatous plaque may become unstable as a result of either plaque erosion or rupture.
Investigation are needed to confirm the diagnosis and assess the need for intervention. The resting electrocardiogram (ECG) is normal in more than half of patients with angina. However, an abnormal ECG substantially increases the probability of coronary disease; in particular, it may show signs of previous myocardial infarction.
Non-invasive testing is helpful.
Exercise testing is useful both in confirming the diagnosis and in giving a guide to prognosis. Alternatives such as myocardial scintigraphy (isotope scanning) and stress echocardiography (ultrasound) provide similar information.
Coronary angiography is regarded as the gold standard for the assessment of CAD and involves the passage of a catheter through the arterial circulation and the injection of radiopaque contrast media into the coronary arteries.
The X-ray images obtained permit confirmation of the diagnosis, aid assessment of prognosis and guide therapy, particularly with regard to suitability for angioplasty and coronary artery bypass grafting.
Non-invasive techniques, including magnetic resonance imaging (MRI) and multi-slice CT scanning, are being developed and tested as alternatives to angiography.
Treatment of stable angina is based on two principles
Improve prognosis by preventing myocardial infarction and death
Relieve or prevent symptoms.
It can be considered a viable alternative to invasive strategies, providing similar results without the complications associated with percutaneous coronary intervention (PCI).In addition, diabetes, hypertension, and dyslipidemia in patients with stable angina should be well controlled. Smoking cessation, without or with pharmacological support, and weight loss should be attempted.
Antithrombotic drugs: One of the major complications arising from atheromatous plaque is thrombus formation. This causes an increase in plaque size and may result in myocardial infarction. Antiplatelet agents, in particular, aspirin, are effective in preventing platelet activation and thus thrombus formation. Aspirin is of proven benefit in all forms of established CHD, although the risk– benefit ratio in people at risk of CHD is less clear.
ACE inhibitors: They are established treatments for hypertension and heart failure and have proven beneficial post myocardial infarction.
Statins: Studies have repeatedly demonstrated the benefit of reducing cholesterol, especially low-density lipoprotein-cholesterol (LDL-C), in patients with CHD.