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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, and excessive alcohol. About half of cases are linked to genetics. Smoking and obesity are associated with about 36% and 20% of cases, respectively. Lack of exercise has been linked to 7–12% of cases. Exposure to the herbicide Agent orange may increase risk. Both rheumatoid arthritis and systemic lupus erythematosus 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. In 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.
Cardiovascular disease affects low- and middle-income countries even more than high-income countries. There is relatively little information regarding social patterns of cardiovascular disease within low- and middle-income countries, but within high-income countries low income and low educational status are consistently associated with greater risk of cardiovascular disease. Policies that have resulted in increased socio-economic inequalities have been associated with greater subsequent socio-economic differences in cardiovascular disease implying a cause and effect relationship. Psychosocial factors, environmental exposures, health behaviours, and health-care access and quality contribute to socio-economic differentials in cardiovascular disease.
Particulate matter has been studied for its short- and long-term exposure effects on cardiovascular disease. Currently, PM is the major focus, in which gradients are used to determine CVD risk. For every 10 μg/m of PM long-term exposure, there was an estimated 8–18% CVD mortality risk. Women had a higher relative risk (RR) (1.42) for PM induced coronary artery disease than men (0.90) did. Overall, long-term PM exposure increased rate of atherosclerosis and inflammation. In regards to short-term exposure (2 hours), every 25 μg/m of PM resulted in a 48% increase of CVD mortality risk. In addition, after only 5 days of exposure, a rise in systolic (2.8 mmHg) and diastolic (2.7 mmHg) blood pressure occurred for every 10.5 μg/m of PM. Other research has implicated PM in irregular heart rhythm, reduced heart rate variability (decreased vagal tone), and most notably heart failure. PM is also linked to carotid artery thickening and increased risk of acute myocardial infarction.
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.
The relation between dietary fat and atherosclerosis is controversial. Writing in "Science", Gary Taubes detailed that political considerations played into the recommendations of government bodies. The USDA, in its food pyramid, promotes a diet of about 64% carbohydrates from total calories. The American Heart Association, the American Diabetes Association and the National Cholesterol Education Program make similar recommendations. In contrast, Prof Walter Willett (Harvard School of Public Health, PI of the second Nurses' Health Study) recommends much higher levels of fat, especially of monounsaturated and polyunsaturated fat. These differing views reach a consensus, though, against consumption of trans fats.
The role of dietary oxidized fats/lipid peroxidation (rancid fats) in humans is not clear.
Laboratory animals fed rancid fats develop atherosclerosis. Rats fed DHA-containing oils experienced marked disruptions to their antioxidant systems, and accumulated significant amounts of phospholipid hydroperoxide in their blood, livers and kidneys.
Rabbits fed atherogenic diets containing various oils were found to undergo the greatest amount of oxidative susceptibility of LDL via polyunsaturated oils. In another study, rabbits fed heated soybean oil "grossly induced atherosclerosis and marked liver damage were histologically and clinically demonstrated." However, Fred Kummerow claims that it is not dietary cholesterol, but oxysterols, or oxidized cholesterols, from fried foods and smoking, that are the culprit.
Rancid fats and oils taste very bad even in small amounts, so people avoid eating them.
It is very difficult to measure or estimate the actual human consumption of these substances. Highly unsaturated omega-3 rich oils such as fish oil are being sold in pill form so that the taste of oxidized or rancid fat is not apparent. The health food industry's dietary supplements are self regulated and outside of FDA regulations. To properly protect unsaturated fats from oxidation, it is best to keep them cool and in oxygen free environments.
In 2011, coronary atherosclerosis was one of the top ten most expensive conditions seen during inpatient hospitalizations in the U.S., with aggregate inpatient hospital costs of $10.4 billion.
Risk factors contributing to PAD are the same as those for atherosclerosis:
- Smoking – tobacco use in any form is the single most important modifiable cause of PAD internationally. Smokers have up to a tenfold increase in relative risk for PAD in a dose-response relationship. Exposure to second-hand smoke from environmental exposure has also been shown to promote changes in blood vessel lining (endothelium) which is a precursor to atherosclerosis. Smokers are 2 to 3 times more likely to have lower extremity peripheral arterial disease than coronary artery disease. More than 80%-90% of patients with lower extremity peripheral arterial disease are current or former smokers. The risk of PAD increases with the number of cigarettes smoked per day and the number of years smoked.
- Diabetes mellitus – causes between two and four times increased risk of PAD by causing endothelial and smooth muscle cell dysfunction in peripheral arteries. The risk of developing lower extremity peripheral arterial disease is proportional to the severity and duration of diabetes.
- Dyslipidemia – a high level of low-density lipoprotein (LDL cholesterol) and a low level of high-density lipoprotein (HDL cholesterol) in the blood) - elevation of total cholesterol, LDL cholesterol, and triglyceride levels each have been correlated with accelerated PAD. Correction of dyslipidemia by diet and/or medication is associated with a major improvement in rates of heart attack and stroke.
- Hypertension – elevated blood pressure is correlated with an increase in the risk of developing PAD, as well as in associated coronary and cerebrovascular events (heart attack and stroke). Hypertension increased the risk of intermittent claudication 2.5- to 4-fold in men and women, respectively.
- Risk of PAD also increases in individuals who are over the age of 50, male, obese, heart attack, or stroke or with a family history of vascular disease.
- Other risk factors which are being studied include levels of various inflammatory mediators such as C-reactive protein, fibrinogen, hyperviscosity, hypercoagulable state.
In 2008, the US had an estimate of 16 million atherosclerotic heart disease and 5.8 million strokes. Cardiovascular diseases that were caused by arteriosclerosis also caused almost 812,000 deaths in 2008, more than any other cause, including cancer. About 1.2 million Americans are predicted to have a heart attack each year.
Hypertension or high blood pressure affects at least 4 billion people worldwide. Hypertensive heart disease is only one of several diseases attributable to high blood pressure. Other diseases caused by high blood pressure include ischemic heart disease, stroke, peripheral arterial disease, aneurysms and kidney disease. Hypertension increases the risk of heart failure by two or three-fold and probably accounts for about 25% of all cases of heart failure. In addition, hypertension precedes heart failure in 90% of cases, and the majority of heart failure in the elderly may be attributable to hypertension. Hypertensive heart disease was estimated to be responsible for 1.0 million deaths worldwide in 2004 (or approximately 1.7% of all deaths globally), and was ranked 13th in the leading global causes of death for all ages. A world map shows the estimated disability-adjusted life years per 100,000 inhabitants lost due to hypertensive heart disease in 2004.
Peripheral arterial disease is more common in the following populations of people:
- All people who have leg symptoms with exertion (suggestive of claudication) or ischemic rest pain.
- All people aged 65 years and over regardless of risk factor status.
- All people between the age of 50 to 69 and who have a cardiovascular risk factor (particularly diabetes or smoking).
- Age less than 50 years, with diabetes and one other atherosclerosis risk factor (smoking, dyslipidemia, hypertension, or hyperhomocysteinemia).
- Individuals with an abnormal lower extremity pulse examination.
- Those with known atherosclerotic coronary, carotid, or renal artery disease.
- All people with a Framingham risk score 10%-20%
- All people who have previously experienced chest pain
There are more women than men with hypertension, and, although men develop hypertension earlier in life, hypertension in women is less well controlled. The consequences of high blood pressure in women are a major public health problem and hypertension is a more important contributory factor in heart attacks in women than men. Until recently women have been under-represented in clinical trials in hypertension and heart failure. Nevertheless, there is some evidence that the effectiveness of antihypertensive drugs differs between men and women and that treatment for heart failure may be less effective in women.
Arteriosclerosis is the thickening, hardening and loss of elasticity of the walls of arteries. This process gradually restricts the blood flow to one's organs and tissues and can lead to severe health risks brought on by atherosclerosis, which is a specific form of arteriosclerosis caused by the buildup of fatty plaques, cholesterol, and some other substances in and on the artery walls.
Many approaches have been promoted as methods to reduce or reverse atheroma progression:
- eating a diet of raw fruits, vegetables, nuts, beans, berries, and grains;
- consuming foods containing omega-3 fatty acids such as fish, fish-derived supplements, as well as flax seed oil, borage oil, and other non-animal-based oils;
- abdominal fat reduction;
- aerobic exercise;
- inhibitors of cholesterol synthesis (known as statins);
- low normal blood glucose levels (glycosylated hemoglobin, also called HbA1c);
- micronutrient (vitamins, potassium, and magnesium) consumption;
- maintaining normal, or healthy, blood pressure levels;
- aspirin supplement
- cyclodextrin can solubilize cholesterol, removing it from plaques
Put simply, take steps to live a healthy, sustainable lifestyle.
In developed countries, with improved public health, infection control and increasing life spans, atheroma processes have become an increasingly important problem and burden for society.
Atheromata continue to be the primary underlying basis for disability and death, despite a trend for gradual improvement since the early 1960s (adjusted for patient age). Thus, increasing efforts towards better understanding, treating and preventing the problem are continuing to evolve.
According to United States data, 2004, for about 65% of men and 47% of women, the first symptom of cardiovascular disease is myocardial infarction (heart attack) or sudden death (death within one hour of symptom onset).
A significant proportion of artery flow-disrupting events occur at locations with less than 50% lumenal narrowing. Cardiac stress testing, traditionally the most commonly performed noninvasive testing method for blood flow limitations, generally only detects lumen narrowing of ~75% or greater, although some physicians advocate nuclear stress methods that can sometimes detect as little as 50%.
The sudden nature of the complications of pre-existing atheroma, vulnerable plaque (non-occlusive or soft plaque), have led, since the 1950s, to the development of intensive care units and complex medical and surgical interventions. Angiography and later cardiac stress testing was begun to either visualize or indirectly detect stenosis. Next came bypass surgery, to plumb transplanted veins, sometimes arteries, around the stenoses and more recently angioplasty, now including stents, most recently drug coated stents, to stretch the stenoses more open.
Yet despite these medical advances, with success in reducing the symptoms of angina and reduced blood flow, atheroma rupture events remain the major problem and still sometimes result in sudden disability and death despite even the most rapid, massive and skilled medical and surgical intervention available anywhere today. According to some clinical trials, bypass surgery and angioplasty procedures have had at best a minimal effect, if any, on improving overall survival. Typically mortality of bypass operations is between 1 and 4%, of angioplasty between 1 and 1.5%.
Additionally, these vascular interventions are often done only after an individual is symptomatic, often already partially disabled, as a result of the disease. It is also clear that both angioplasty and bypass interventions do not prevent future heart attack.
The older methods for understanding atheroma, dating to before World War II, relied on autopsy data. Autopsy data has long shown initiation of fatty streaks in later childhood with slow asymptomatic progression over decades.
One way to see atheroma is the very invasive and costly IVUS ultrasound technology; it gives us the precise volume of the inside intima plus the central media layers of about of artery length. Unfortunately, it gives no information about the structural strength of the artery. Angiography does not visualize atheroma; it only makes the blood flow within blood vessels visible. Alternative methods that are non or less physically invasive and less expensive per individual test have been used and are continuing to be developed, such as those using computed tomography (CT; led by the electron beam tomography form, given its greater speed) and magnetic resonance imaging (MRI). The most promising since the early 1990s has been EBT, detecting calcification within the atheroma before most individuals start having clinically recognized symptoms and debility. Interestingly, statin therapy (to lower cholesterol) does not slow the speed of calcification as determined by CT scan. MRI coronary vessel wall imaging, although currently limited to research studies, has demonstrated the ability to detect vessel wall thickening in asymptomatic high risk individuals. As a non-invasive, ionising radiation free technique, MRI based techniques could have future uses in monitoring disease progression and regression. Most visualization techniques are used in research, they are not widely available to most patients, have significant technical limitations, have not been widely accepted and generally are not covered by medical insurance carriers.
From human clinical trials, it has become increasingly evident that a more effective focus of treatment is slowing, stopping and even partially reversing the atheroma growth process. There are several prospective epidemiologic studies including the Atherosclerosis Risk in Communities (ARIC) Study and the Cardiovascular Health Study (CHS), which have supported a direct correlation of Carotid Intima-media thickness (CIMT) with myocardial infarction and stroke risk in patients without cardiovascular disease history. The ARIC Study was conducted in 15,792 individuals between 5 and 65 years of age in four different regions of the US between 1987 and 1989. The baseline CIMT was measured and measurements were repeated at 4- to 7-year intervals by carotid B mode ultrasonography in this study. An increase in CIMT was correlated with an increased risk for CAD. The CHS was initiated in 1988, and the relationship of CIMT with risk of myocardial infarction and stroke was investigated in 4,476 subjects ≤65 years of age. At the end of approximately six years of follow-up, CIMT measurements were correlated with cardiovascular events.
Paroi artérielle et Risque Cardiovasculaire in Asia Africa/Middle East and Latin America (PARC-AALA) is another important large-scale study, in which 79 centers from countries in Asia, Africa, the Middle East, and Latin America participated, and the distribution of CIMT according to different ethnic groups and its association with the Framingham cardiovascular score was investigated. Multi-linear regression analysis revealed that an increased Framingham cardiovascular score was associated with CIMT, and carotid plaque independent of geographic differences.
Cahn et al. prospectively followed-up 152 patients with coronary artery disease for 6–11 months by carotid artery ultrasonography and noted 22 vascular events (myocardial infarction, transient ischemic attack, stroke, and coronary angioplasty) within this time period. They concluded that carotid atherosclerosis measured by this non-interventional method has prognostic significance in coronary artery patients.
In the Rotterdam Study, Bots et al. followed 7,983 patients >55 years of age for a mean period of 4.6 years, and reported 194 incident myocardial infarctions within this period. CIMT was significantly higher in the myocardial infarction group compared to the other group. Demircan et al. found that the CIMT of patients with acute coronary syndrome were significantly increased compared to patients with stable angina pectoris.
It has been reported in another study that a maximal CIMT value of 0.956 mm had 85.7% sensitivity and 85.1% specificity to predict angiographic CAD. The study group consisted of patients admitted to the cardiology outpatient clinic with symptoms of stable angina pectoris. The study showed CIMT was higher in patients with significant CAD than in patients with non-critical coronary lesions. Regression analysis revealed that thickening of the mean intima-media complex more than 1.0 was predictive of significant CAD our patients. There was incremental significant increase in CIMT with the number coronary vessel involved. In accordance with the literature, it was found that CIMT was significantly higher in the presence of CAD. Furthermore, CIMT was increased as the number of involved vessels increased and the highest CIMT values were noted in patients with left main coronary involvement. However, human clinical trials have been slow to provide clinical & medical evidence, partly because the asymptomatic nature of atheromata make them especially difficult to study. Promising results are found using carotid intima-media thickness scanning (CIMT can be measured by B-mode ultrasonography), B-vitamins that reduce a protein corrosive, homocysteine and that reduce neck carotid artery plaque volume and thickness, and stroke, even in late-stage disease.
Additionally, understanding what drives atheroma development is complex with multiple factors involved, only some of which, such as lipoproteins, more importantly lipoprotein subclass analysis, blood sugar levels and hypertension are best known and researched. More recently, some of the complex immune system patterns that promote, or inhibit, the inherent inflammatory macrophage triggering processes involved in atheroma progression are slowly being better elucidated in animal models of atherosclerosis.
Arteriosclerotic heart disease (ASHD), is a thickening and hardening of the walls of the coronary arteries. Atherosclerosis is a potentially serious condition where arteries become clogged with fatty substances called plaques, or atheroma.
For those at high risk, a combination of lifestyle modification and statins has been shown to decrease mortality.
A 2017 SBU report found evidence that workplace exposure to silica dust, engine exhaust or welding fumes is associated with heart disease. Associations also exist for exposure to arsenic, benzopyrenes, lead, dynamite, carbon disulphide, carbon monoxide, metalworking fluids and occupational exposure to tobacco smoke. Working with the electrolytic production of aluminium or the production of paper when the sulphate pulping process is used is associated with heart disease. An association was also found between heart disease and exposure to compounds which are no longer permitted in certain work environments, such as phenoxy acids containing TCDD(dioxin) or asbestos.
Workplace exposure to silica dust or asbestos is also associated with pulmonary heart disease. There is evidence that workplace exposure to lead, carbon disulphide, phenoxyacids containing TCDD, as well as working in an environment where aluminium is being electrolytically produced, is associated with stroke.
Smoking does not directly cause high blood pressure. However it is a known risk factor for other serious cardiovascular disease.
Arterial stiffness occurs as a consequence of biological aging and arteriosclerosis. Inflammation plays a major role in arteriosclerosis development, and consequently it is a major contributor in large arteries stiffening. Increased arterial stiffness is associated with an increased risk of cardiovascular events such as myocardial infarction and stroke, the two leading causes of death in the developed world. The World Health Organisation predicts that in 2010, cardiovascular disease will also be the leading killer in the developing world and represents a major global health problem.
Several degenerative changes that occur with age in the walls of large elastic arteries are thought to contribute to increased stiffening over time, including the mechanical fraying of lamellar elastin structures within the wall due to repeated cycles of mechanical stress; changes in the kind and increases in content of arterial collagen proteins, partially as a compensatory mechanism against the loss of arterial elastin and partially due to fibrosis; and crosslinking of adjacent collagen fibers by advanced glycation endproducts (AGEs).
Genetic contributions are usually due to the additive effects of multiple genes, though occasionally may be due to a single gene defect such as in the case of familial hypercholesterolaemia.
Genetic abnormalities are in some cases completely responsible for hypercholesterolemia, such as in familial hypercholesterolemia, where one or more genetic mutations in the autosomal dominant APOB gene exist, the autosomal recessive "LDLRAP1" gene, autosomal dominant familial hypercholesterolemia ("HCHOLA3") variant of the "PCSK9" gene, or the LDL receptor gene. Familial hypercholesterolemia affects about one in five hundred people.
When the heart contracts it generates a pulse or energy wave that travels through the circulatory system. The speed of travel of this pulse wave (pulse wave velocity (PWV)) is related to the stiffness of the arteries. Other terms that are used to describe the mechanical properties of arteries include elastance, or the reciprocal (inverse) of elastance, compliance. The relationship between arterial stiffness and pulse wave velocity was first predicted by Thomas Young in his Croonian Lecture of 1808 but is generally described by the Moens–Korteweg equation or the Bramwell–Hill equation. Typical values of PWV in the aorta range from approximately 5 m/s to >15 m/s.
Measurement of aortic PWV provides some of the strongest evidence concerning the prognostic significance of large artery stiffening. Increased aortic PWV has been shown to predict cardiovascular, and in some cases all cause, mortality in individuals with end stage renal failure, hypertension, diabetes mellitus and in the general population. However, at present, the role of measurement of PWV as a general clinical tool remains to be established. Devices are on the market that measure arterial stiffness parameters (augmentation index, pulse wave velocity). These include the Complior, CVProfilor, PeriScope, Hanbyul Meditech, Mobil-O-Graph NG, BP Plus (Pulsecor), PulsePen, BPLab Vasotens, Arteriograph, Vascular Explorer, and SphygmoCor.
Kidney failure is very common in patients suffering from congestive heart failure. It was shown that kidney failure complicates one-third of all admissions for heart failure, which is the leading cause of hospitalization in the United States among adults over 65 years old. These complications led to longer hospital stay, higher mortality, and greater chance for readmission. Another study found that 39% of patients in NYHA class 4 and 31% of patients in NYHA class 3 had severely impaired kidney function. Similarly, kidney failure can have deleterious effects on cardiovascular function. It was estimated that about 44% of deaths in patients with end-stage kidney failure (ESKF) are due to cardiovascular disease.
A 2015 SBU-report including a systematic review of non-chemical riskfactors for occupation cardiovascular disease found an association between certain occupational risk factors and developing cardiovascular disease in those:
- With mentally stressfull work with a lack of control of their own working situation — with a effort-reward imbalance
- Who experience low social support at work; who experience injustice or experience insufficient opportunities for personal development; or those who experience job insecurity
- Those who work night schedules; or have long working weeks
- Those who are exposed to noise
Specifically the risk of stroke was also increased by:
- Exposure to ionizing radiation
Hypertension develops more often in those who experience job strain and who have shift-work. Differences between women and men in risk are small, however men risk suffering and dieing of heart attacks or stroke twice as often as women during working life.
It has been suggested that vitamin D deficiency is associated with cardiovascular risk factors. It has been observed that individuals with a vitamin D deficiency have higher systolic and diastolic blood pressures than average. Vitamin D inhibits renin secretion and its activity, it therefore acts as a "negative endocrine regulator of the renin-angiotensin system". Hence, a deficiency in vitamin D leads to an increase in renin secretion. This is one possible mechanism of explaining the observed link between hypertension and vitamin D levels in the blood plasma.
Also, some authorities claim that potassium might both prevent and treat hypertension.
The following risk factors have been associated with increased incidence of CRS.
- Older age
- Comorbid conditions (diabetes mellitus, uncontrolled hypertension, anemia)
- Drugs (anti-inflammatory agents, diuretics, ACE inhibitors, ARBs)
- History of heart failure or impaired left ventricular ejection fraction
- Prior myocardial infarction
- New York Heart Association (NYHA) functional class
- Elevated cardiac troponins
- Chronic kidney disease (reduced eGFR, elevated BUN, creatinine, or cystatin)