Coronary artery disease ( CAD), also called coronary heart disease ( CHD), or ischemic heart disease ( IHD),
is a type of heart disease involving Ischemia to the cardiac muscle due to a build-up of atheromatous plaque in the arteries of the heart. It is the most common of the cardiovascular diseases. CAD can cause stable angina, unstable angina, myocardial ischemia, and myocardial infarction.A common symptom is angina, which is chest pain or discomfort that may travel into the shoulder, arm, back, neck, or jaw. Occasionally it may feel like heartburn. In stable angina, 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 Heart arrhythmia.
Risk factors include high blood pressure, tobacco smoking, diabetes mellitus, lack of exercise, obesity, high blood cholesterol, poor diet, depression, and excessive alcohol consumption.
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 males than females of a given age.
With advanced disease, 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 and has an increased oxygen demand. For some, this causes severe symptoms, while others experience no symptoms at all.
Job stress appears to play a minor role, accounting for about 3% of cases. In one study, females who were free of stress from work life saw an increase in the diameter of their blood vessels, leading to decreased progression of atherosclerosis. In contrast, females who had high levels of work-related stress experienced a decrease in the diameter of their blood vessels and significantly increased disease progression.
High levels of cholesterol in the bloodstream lead to atherosclerosis. With increased levels of LDL in the bloodstream, "LDL particles will form deposits and accumulate within the arterial walls, which will lead to the development of plaques, restricting blood flow". The resultant reduction in the heart's blood supply due to atherosclerosis in coronary arteries "causes shortness of breath, angina pectoris (chest pains that are usually relieved by rest), and potentially fatal heart attacks (myocardial infarctions)".
The RNA changes are mostly related to ciliary and endocytic transcripts, which in the circulating immune system would be related to the immune synapse. One of the most differentially expressed genes, fibromodulin (FMOD), which is increased 2.8-fold in CAD, is found mainly in connective tissue and is a modulator of the TGF-beta signaling pathway. However, not all RNA changes may be related to the immune synapse. For example, Nebulette, the most down-regulated transcript (2.4-fold), is found in cardiac muscle; it is a 'cytolinker' that connects actin and desmin to facilitate cytoskeletal function and vesicular movement. The endocytic pathway is further modulated by changes in tubulin, a key microtubule protein, and fidgetin, a tubulin-severing enzyme that is a marker for cardiovascular risk identified by genome-wide association study. Protein recycling would be modulated by changes in the proteasomal regulator SIAH3 and the ubiquitin ligase MARCHF10. On the ciliary aspect of the immune synapse, several of the modulated transcripts are related to ciliary length and function. STRC is a partner to mesothelin, a related superhelix protein, whose transcript is also modulated in CAD. DCDC2, a double-cortin protein, modulates ciliary length. In the signaling pathways of the immune synapse, numerous transcripts are directly related to T-cell function and the control of differentiation. Butyrophilin is a co-regulator for T cell activation. Fibromodulin modulates the TGF-beta signaling pathway, a primary determinant of Tre differentiation. Further impact on the TGF-beta pathway is reflected in concurrent changes in the BMP receptor 1B RNA (BMPR1B), because the bone morphogenic proteins are members of the TGF-beta superfamily, and likewise impact Treg differentiation. Several of the transcripts (TMEM98, NRCAM, SFRP5, SHISA2) are elements of the Wnt signaling pathway, which is a major determinant of Treg differentiation.
Typically, coronary artery disease occurs when part of the smooth, elastic lining inside a coronary artery (the arteries that supply blood to the heart muscle) develops atherosclerosis. With atherosclerosis, the artery's lining becomes hardened, stiffened, and accumulates deposits of calcium, fatty lipids, and abnormal inflammatory cells – to form a plaque. Calcium phosphate (hydroxyapatite) deposits in the muscular layer of the blood vessels appear to play a significant role in stiffening the arteries and inducing the early phase of coronary arteriosclerosis. This can be seen in a so-called metastatic mechanism of calciphylaxis as it occurs in chronic kidney disease and hemodialysis. Although these people have kidney dysfunction, almost fifty percent of them die due to coronary artery disease. Plaques can be thought of as large "pimples" that protrude into the channel of an artery, causing partial obstruction to blood flow. People with coronary artery disease might have just one or two plaques or might have dozens distributed throughout their coronary arteries. A more severe form is chronic total occlusion (CTO) when a coronary artery is completely obstructed for more than 3 months.
Microvascular angina is a type of angina pectoris in which chest pain and chest discomfort occur without signs of blockages in the larger coronary arteries of their hearts when an angiogram (coronary angiogram) is being performed. The exact cause of microvascular angina is unknown. Explanations include microvascular dysfunction or epicardial atherosclerosis. For reasons that are not well understood, females are more likely than males to have it; however, and other risk factors unique to females may play a role.
For stable symptomatic patients, several non-invasive tests can diagnose CAD depending on pre-assessment of the risk profile. Noninvasive imaging options include; Computed tomography angiography (CTA) (anatomical imaging, best test in patients with low-risk profile to "rule out" the disease), positron emission tomography (PET), single-photon emission computed tomography (SPECT)/nuclear stress test/myocardial scintigraphy and stress echocardiography (the three latter can be summarized as functional noninvasive methods and are typically better to "rule in"). Exercise ECG or stress test is inferior to non-invasive imaging methods due to the risk of false-negative and false-positive test results. The use of non-invasive imaging is not recommended on individuals who are exhibiting no symptoms and are otherwise at low risk for developing coronary disease., citing
The diagnosis of microvascular angina (previously known as cardiac syndrome X – the rare coronary artery disease that is more common in females, as mentioned, is a diagnosis of exclusion. Therefore, usually, the same tests are used as in any person suspected of having coronary artery disease:
In minor to moderate cases, nitroglycerine may be used to alleviate acute symptoms of stable angina or may be used immediately before exertion to prevent the onset of angina. Sublingual nitroglycerine is most commonly used to provide rapid relief for acute angina attacks and as a complement to anti-anginal treatments in patients with refractory and recurrent angina. When nitroglycerine enters the bloodstream, it forms free radical nitric oxide, or NO, which activates guanylate cyclase and in turn stimulates the release of cyclic GMP. This molecular signaling stimulates smooth muscle relaxation, resulting in vasodilation and consequently improved blood flow to heart regions affected by atherosclerotic plaque.
Stable coronary artery disease (SCAD) is also often called stable ischemic heart disease (SIHD).
Polygenic score is another way of risk assessment. In one study, the relative risk of incident coronary events was 91% higher among participants at high genetic risk than among those at low genetic risk.
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.
A 2024 study published in The Lancet Diabetes & Endocrinology found that the oral glucose tolerance test (OGTT) is more effective than hemoglobin A1c (HbA1c) for detecting dysglycemia in patients with coronary artery disease. The study highlighted that 2-hour post-load glucose levels of at least 9 mmol/L were strong predictors of cardiovascular outcomes, while HbA1c levels of at least 5.9% were also significant but not independently associated when combined with OGTT results.
The consumption of trans fat (commonly found in Hydrogenation products such as margarine) has been shown to cause a precursor to atherosclerosis 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).
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.
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. 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
Early studies suggested that antibiotics might help patients with coronary disease reduce the risk of heart attacks and strokes. However, a 2021 Cochrane meta-analysis found that antibiotics given for secondary prevention of coronary heart disease are harmful to people with increased mortality and occurrence of stroke. So, antibiotic use is not currently supported for preventing secondary coronary heart disease.
It is recommended that blood pressure typically be reduced to less than 140/90 mmHg. The diastolic blood pressure should not be below 60 mmHg. Beta-blockers are recommended first line for this use.
]] 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.
The World Health Organization reported that: "The world's biggest killer is ischemic heart disease, responsible for 13% of the world's total deaths. Since 2000, the largest increase in deaths has been for this disease, rising by 2.7 million to 9.1 million deaths in 2021."
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. Indian Heart Association Why South Asians Facts , 29 April 2015; accessed 26 October 2015.
Coronary artery disease is the leading cause of death for both males and females 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 males will develop CAD in the future, and one in three healthy 40-year-old females. It is the most common reason for death of males and females over 20 years of age in the United States.
After analysing data from 2 111 882 patients, the recent meta-analysis revealed that the incidence of coronary artery diseases in breast cancer survivors was 4.29 (95% CI 3.09–5.94) per 1000 person-years.
A more controversial link is that between Chlamydophila pneumoniae infection and atherosclerosis. While this intracellular organism has been demonstrated in atherosclerotic plaques, evidence is inconclusive regarding whether it can be considered a causative factor. Treatment with antibiotics in patients with proven atherosclerosis has not demonstrated a decreased risk of heart attacks or other coronary vascular diseases.
Myeloperoxidase has been proposed as a biomarker.
Plant-based nutrition has been suggested as a way to reverse coronary artery disease, but strong evidence is still lacking for claims of potential benefits.
Several immunosuppressive drugs targeting the chronic inflammation in coronary artery disease have been tested.
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