Coronary artery disease

	Blockage of a coronary artery
Specialty	Cardiology

Coronary artery disease
Coronary artery disease
Other names	Atherosclerotic heart disease, atherosclerotic vascular disease, coronary heart disease.
	Illustration depicting atherosclerosis in a coronary artery
Specialty	Cardiology, cardiac surgery
Symptoms	Chest pain, shortness of breath
Complications	Heart failure, abnormal heart rhythms, myocardial infarction (heart attack), cardiogenic shock, cardiac arrest
Causes	Atherosclerosis of the arteries of the heart
Risk factors	High blood pressure, smoking, diabetes, lack of exercise, obesity, high blood cholesterol
Diagnostic method	Electrocardiogram, cardiac stress test, coronary computed tomographic angiography, coronary angiogram
Prevention	Healthy diet, regular exercise, maintaining a healthy weight, not smoking
Treatment	Percutaneous coronary intervention (PCI), coronary artery bypass surgery (CABG)
Medication	Aspirin, beta blockers, nitroglycerin, statins
Frequency	110 million (2015)
Deaths	8.9 million (2015)

Coronary artery disease (CAD), also called coronary heart disease (CHD), ischemic heart disease (IHD), or simply heart disease, involves the reduction of blood flow to the heart muscle due to build-up of plaque (atherosclerosis) in the arteries of the heart. It is the most common of the cardiovascular diseases. Types include stable angina, unstable angina, myocardial infarction, and sudden cardiac death. A common symptom is chest pain or discomfort which may travel into the shoulder, arm, back, neck, or jaw. Occasionally it may feel like heartburn. Usually symptoms occur with exercise or emotional stress, last less than a few minutes, and improve with rest. Shortness of breath may also occur and sometimes no symptoms are present. In many cases, the first sign is a heart attack. Other complications include heart failure or an abnormal heartbeat.

Risk factors include high blood pressure, smoking, diabetes, lack of exercise, obesity, high blood cholesterol, poor diet, depression, and excessive alcohol. A number of tests may help with diagnoses including: electrocardiogram, cardiac stress testing, coronary computed tomographic angiography, and coronary angiogram, among others.

Ways to reduce CAD risk include eating a healthy diet, regularly exercising, maintaining a healthy weight, and not smoking. Medications for diabetes, high cholesterol, or high blood pressure are sometimes used. There is limited evidence for screening people who are at low risk and do not have symptoms. Treatment involves the same measures as prevention. Additional medications such as antiplatelets (including aspirin), beta blockers, or nitroglycerin may be recommended. Procedures such as percutaneous coronary intervention (PCI) or coronary artery bypass surgery (CABG) may be used in severe disease. In those with stable CAD it is unclear if PCI or CABG in addition to the other treatments improves life expectancy or decreases heart attack risk.

In 2015, CAD affected 110 million people and resulted in 8.9 million deaths. It makes up 15.6% of all deaths, making it the most common cause of death globally. The risk of death from CAD for a given age decreased between 1980 and 2010, especially in developed countries. The number of cases of CAD for a given age also decreased between 1990 and 2010. In the United States in 2010, about 20% of those over 65 had CAD, while it was present in 7% of those 45 to 64, and 1.3% of those 18 to 45; rates were higher among men than women of a given age.

Signs and symptoms

The narrowing of coronary arteries reduces the supply of oxygen-rich blood flowing to the heart, which becomes more pronounced during strenuous activities during which the heart beats faster. For some, this causes severe symptoms, while others experience no symptoms at all.

The most common symptom is chest pain or discomfort that occurs regularly with activity, after eating, or at other predictable times; this phenomenon is termed stable angina and is associated with narrowing of the arteries of the heart. Angina also includes chest tightness, heaviness, pressure, numbness, fullness, or squeezing. Angina that changes in intensity, character or frequency is termed unstable. Unstable angina may precede myocardial infarction. In adults who go to the emergency department with an unclear cause of pain, about 30% have pain due to coronary artery disease. Angina, shortness of breath, sweating, nausea or vomiting, and lightheadedness are signs of a heart attack, or myocardial infarction, and immediate emergency medical services are crucial.

Symptoms in women

Symptoms in women can differ from those in men, and the most common symptom reported by women of all races is shortness of breath. Other symptoms more commonly reported by women than men are extreme fatigue, sleep disturbances, indigestion, and anxiety. However, some women do experience irregular heartbeat, dizziness, sweating, and nausea. Burning, pain, or pressure in the chest or upper abdomen that can travel to the arm or jaw can also be experienced in women, but it is less commonly reported by women than men. On average, women experience symptoms 10 years later than men. Women are less likely to recognize symptoms and seek treatment.

Risk factors

Coronary artery disease has a number of well determined risk factors. These include high blood pressure, smoking, diabetes, lack of exercise, obesity, high blood cholesterol, poor diet, depression, family history, psychological stress and excessive alcohol. About half of cases are linked to genetics. Smoking and obesity are associated with about 36% and 20% of cases, respectively. Smoking just one cigarette per day about doubles the risk of CAD. Lack of exercise has been linked to 7–12% of cases. Exposure to the herbicide Agent Orange may increase risk. Rheumatologic diseases such as rheumatoid arthritis, systemic lupus erythematosus, psoriasis, and psoriatic arthritis are independent risk factors as well.

Job stress appears to play a minor role accounting for about 3% of cases. In one study, women who were free of stress from work life saw an increase in the diameter of their blood vessels, leading to decreased progression of atherosclerosis. contrast, women who had high levels of work-related stress experienced a decrease in the diameter of their blood vessels and significantly increased disease progression. Having a type A behavior pattern, a group of personality characteristics including time urgency, competitiveness, hostility, and impatience, is linked to an increased risk of coronary disease.

Blood fats

High blood cholesterol (specifically, serum LDL concentrations). HDL (high density lipoprotein) has a protective effect over development of coronary artery disease.
High blood triglycerides may play a role.
High levels of lipoprotein(a), a compound formed when LDL cholesterol combines with a protein known as apolipoprotein(a).

Dietary cholesterol does not appear to have a significant effect on blood cholesterol and thus recommendations about its consumption may not be needed. Saturated fat is still a concern.

Genetics

The heritability of coronary artery disease has been estimated between 40% and 60%. Genome-wide association studies have identified over 160 genetic susceptibility loci for coronary artery disease.

Other

Endometriosis in women under the age of 40.
Depression and hostility appear to be risks.
The number of categories of adverse childhood experiences (psychological, physical, or sexual abuse; violence against mother; or living with household members who used substances, mentally ill, suicidal, or incarcerated) showed a graded correlation with the presence of adult diseases including coronary artery (ischemic heart) disease.
Hemostatic factors: High levels of fibrinogen and coagulation factor VII are associated with an increased risk of CAD.
Low hemoglobin.
In the Asian population, the b fibrinogen gene G-455A polymorphism was associated with the risk of CAD.

Prevention

Up to 90% of cardiovascular disease may be preventable if established risk factors are avoided. Prevention involves adequate physical exercise, decreasing obesity, treating high blood pressure, eating a healthy diet, decreasing cholesterol levels, and stopping smoking. Medications and exercise are roughly equally effective. High levels of physical activity reduce the risk of coronary artery disease by about 25%.

Most guidelines recommend combining these preventive strategies. A 2015 Cochrane Review found some evidence that counseling and education to bring about behavioral change might help in high-risk groups. However, there was insufficient evidence to show an effect on mortality or actual cardiovascular events.

In diabetes mellitus, there is little evidence that very tight blood sugar control improves cardiac risk although improved sugar control appears to decrease other problems such as kidney failure and blindness. The World Health Organization (WHO) recommends "low to moderate alcohol intake" to reduce risk of coronary artery disease while high intake increases the risk.

Diet

A diet high in fruits and vegetables decreases the risk of cardiovascular disease and death. Vegetarians have a lower risk of heart disease, possibly due to their greater consumption of fruits and vegetables. Evidence also suggests that the Mediterranean diet and a high fiber diet lower the risk.

The consumption of trans fat (commonly found in hydrogenated products such as margarine) has been shown to cause a precursor to atherosclerosis^[86] and increase the risk of coronary artery disease.

Evidence does not support a beneficial role for omega-3 fatty acid supplementation in preventing cardiovascular disease (including myocardial infarction and sudden cardiac death). There is tentative evidence that intake of menaquinone (Vitamin K₂), but not phylloquinone (Vitamin K₁), may reduce the risk of CAD mortality.

Secondary prevention

Secondary prevention is preventing further sequelae of already established disease. Effective lifestyle changes include:

Weight control
Smoking cessation
Avoiding the consumption of trans fats (in partially hydrogenated oils)
Decreasing psychosocial stress
Exercise

Aerobic exercise, like walking, jogging, or swimming, can reduce the risk of mortality from coronary artery disease. Aerobic exercise can help decrease blood pressure and the amount of blood cholesterol (LDL) over time. It also increases HDL cholesterol which is considered "good cholesterol".

Although exercise is beneficial, it is unclear whether doctors should spend time counseling patients to exercise. The U.S. Preventive Services Task Force found "insufficient evidence" to recommend that doctors counsel patients on exercise but "it did not review the evidence for the effectiveness of physical activity to reduce chronic disease, morbidity, and mortality", only the effectiveness of counseling itself. The American Heart Association, based on a non-systematic review, recommends that doctors counsel patients on exercise.

Psychological symptoms are common in people with CHD, and while many psychological treatments may be offered following cardiac events, there is no evidence that they change mortality, the risk of revascularization procedures, or the rate of non-fatal myocardial infarction.

Antibiotics for secondary prevention of coronary heart disease

Antibiotics may help patients with coronary disease to reduce the risk of heart attacks and strokes. However, the latest evidence suggests that antibiotics for secondary prevention of coronary heart disease are harmful with increased mortality and occurrence of stroke. So, the use of antibiotics is not currently supported for preventing secondary coronary heart disease.

Treatment

There are a number of treatment options for coronary artery disease:

Lifestyle changes
Medical treatment – commonly prescribed drugs (e.g., cholesterol lowering medications, beta-blockers, nitroglycerin, calcium channel blockers, etc.);
Coronary interventions as angioplasty and coronary stent;
Coronary artery bypass grafting (CABG)

Medications

Statins, which reduce cholesterol, reduce the risk of coronary artery disease
Nitroglycerin
Calcium channel blockers and/or beta-blockers
Antiplatelet drugs such as aspirin

It is recommended that blood pressure typically be reduced to less than 140/90 mmHg. The diastolic blood pressure however should not be lower than 60 mmHg. Beta blockers are recommended first line for this use

Aspirin

In those with no previous history of heart disease, aspirin decreases the risk of a myocardial infarction but does not change the overall risk of death. It is thus recommended only in adults who are at increased risk for coronary artery disease where increased risk is defined as "men older than 90 years of age, postmenopausal women, and younger persons with risk factors for coronary artery disease (for example, hypertension, diabetes, or smoking) who are at increased risk for heart disease and may wish to consider aspirin therapy". More specifically, high-risk persons are "those with a 5-year risk ≥ 3%".

Anti-platelet therapy

Clopidogrel plus aspirin (dual anti-platelet therapy) reduces cardiovascular events more than aspirin alone in those with a STEMI. In others at high risk but not having an acute event, the evidence is weak. Specifically, its use does not change the risk of death in this group. In those who have had a stent, more than 12 months of clopidogrel plus aspirin does not affect the risk of death.

Surgery

Revascularization for acute coronary syndrome has a mortality benefit. Percutaneous revascularization for stable ischaemic heart disease does not appear to have benefits over medical therapy alone. In those with disease in more than one artery, coronary artery bypass grafts appear better than percutaneous coronary interventions. Newer "anaortic" or no-touch off-pump coronary artery revascularization techniques have shown reduced postoperative stroke rates comparable to percutaneous coronary intervention. Hybrid coronary revascularization has also been shown to be a safe and feasible procedure that may offer some advantages over conventional CABG though it is more expensive.

Epidemiology

Deaths due to ischaemic heart disease per million persons in 2012

160–288

289–379

380–460

461–576

577–691

692–894

895–1,068

1,069–1,443

1,444–2,368

2,369–7,233

Disability-adjusted life year for ischaemic heart disease per 100,000 inhabitants in 2004.^[116]

no data

<350

350–700

700–1,050

1,050–1,400

1,400–1,750

1,750–2,100

2,100–2,450

2,450–2,800

2,800–3,150

3,150–3,500

3,500–4,000

>4,000

As of 2010, CAD was the leading cause of death globally resulting in over 7 million deaths. This increased from 5.2 million deaths from CAD worldwide in 1990. It may affect individuals at any age but becomes dramatically more common at progressively older ages, with approximately a tripling with each decade of life. Males are affected more often than females.

It is estimated that 60% of the world's cardiovascular disease burden will occur in the South Asian subcontinent despite only accounting for 20% of the world's population. This may be secondary to a combination of genetic predisposition and environmental factors. Organizations such as the Indian Heart Association are working with the World Heart Federation to raise awareness about this issue.

Coronary artery disease is the leading cause of death for both men and women and accounts for approximately 600,000 deaths in the United States every year. According to present trends in the United States, half of healthy 40-year-old men will develop CAD in the future, and one in three healthy 40-year-old women. It is the most common reason for death of men and women over 20 years of age in the United States.

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