RISK FACTORS AND PREVENTION MEASURES

CAD progresses slowly. In most patients, atherosclerosis builds over decades. The process begins before most people are out of their teenage years, but the coronary effects of atherosclerosis usually do not show up until middle age.

The most common symptom of coronary artery disease is chest pain, which can be accompanied by dyspnea and fatigue. These are the symptoms that often bring the patient with CAD to see a healthcare provider. CAD can also be asymptomatic for years. Those patients who have been diagnosed with CAD because of occasional, temporary chest discomfort can at the same time be suffering acute “silent” MIs without apparent symptoms.

More than half of the patients who die suddenly from CAD have had no previous symptoms. Frequently, those patients who suffer from silent MIs also have type 2 diabetes or other risk factors that may accelerate the effects of the disease and increase the mortality rate. Some of these risk factors are preventable or may be treated with lifestyle changes to improve outcomes. Other risk factors cannot be prevented or improved (Virani et al., 2021).

Nonpreventable Risk Factors

AGE

Age is the strongest risk factor for coronary artery disease. Most cases occur in patients aged 40 years or older, although mortality and morbidity are higher in the elderly. More than 80% of people who die of CAD are ages 65 years or older. Elderly women who have heart attacks are more likely than men are to die from them within a few weeks (Cleveland Clinic, 2021a).

GENDER

Men are at slightly higher risk than women to have MIs and have them at an earlier age than women. It is thought that the higher estrogen levels in premenopausal women protect them from some of the heart damage done by atherosclerosis, but this protection disappears after menopause. Women are more likely than men to die of an MI, possibly because they are so much older when the MI occurs (Cleveland Clinic, 2021a).

ETHNICITY

Disparities in CAD due to ethnicity may be due to a complex set of issues including diet, obesity, lack of access to care, mistrust of healthcare workers, fewer ethnic minority healthcare professionals to relate to, and more.

African Americans have a higher prevalence of, and a higher death rate from, CAD than European Americans. In part, the difference results from the higher incidence of hypertension, obesity, and metabolic syndrome among African Americans. This racial disparity is also thought to result from the fact that African Americans, on average, tend to seek treatment later than European Americans for a variety of reasons regarding access, past and present. African Americans are also less likely to receive invasive treatment.

Heart disease risk is also higher among Mexican Americans, American Indians, Native Hawaiians, and some Asian Americans. This may be due in part to higher rates of obesity and diabetes in these populations. African Americans tend to have more severe high blood pressure than Whites and a higher risk of heart disease (Cleveland Clinic, 2021a).

GENETICS/FAMILY HISTORY

Children of parents with heart disease are more likely to develop it themselves. Most people with a strong family history of heart disease have one or more other contributing risk factors (Cleveland Clinic, 2021a).

First-degree relatives who are biologically related (parents, children, and siblings) share approximately 50% of their genetic material with each other. For this reason, members of the same family tend to inherit the same diseases and traits. It is sometimes difficult to determine if genetics is the basis for CAD in families or if environmental risk behaviors such as smoking or obesity contribute to the appearance of the same diseases in families.

A genetic disorder can change the way that a protein works so that the body processes cholesterol differently. This may increase the occurrence of atherosclerosis. Genetic differences are inherited in the DNA of the ovum and sperm. The parents’ genetic code is copied into every cell of the offspring (UOHI, 2021).

Preventable Risk Factors and Evidenced-Based Prevention Measures

SMOKING/TOBACCO USE

In the United States, smoking has decreased 24% in the past 50 years but remains a serious health problem. People who smoke have a risk of developing CAD or lung disease that is 30% higher than that of nonsmokers. Nicotine causes the sympathetic nervous system to constrict arteries and raises blood pressure, causing arterial wall damage. The damage encourages the formation of atherosclerotic plaque.

Cigarette smoking is also an important independent risk factor for sudden cardiac death in patients with CAD. Cigarette smoking adds a cumulative effect when other risk factors are present to greatly increase the risk for CAD. People who smoke cigars, pipes, e-cigarettes, or “vape” seem to have a higher risk of death from CAD as well. The mortality rate for current smokers is three times that of people who have never smoked. Exposure to secondhand smoke also increases the risk of heart disease for nonsmokers (Cleveland Clinic, 2021a).

Patients who smoke should be strongly encouraged to quit smoking. An important factor is to educate patients on the risks of smoking and offer assistance in developing an action plan to help the patient stop smoking. The best smoking cessation programs include a combination of the following components:

• Behavioral modification therapies
• Medications such as antidepressants
• Nicotine replacement strategies such as patches or gum
• Counseling to make a plan to quit smoking
• Smoking cessation “quit lines” (such as 1-800-NOBUTTS)
• Free texting programs (e.g., SmokefreeTXT)
  (CDC, 2021a)

HIGH CHOLESTEROL

As cholesterol rises in the blood, so does the risk of CAD. When other risk factors (e.g., hypertension and smoking) are present, this risk increases even more. Low high-density lipoprotein (HDL) cholesterol is also a risk factor for heart disease. Likewise, a high triglyceride level combined with low HDL cholesterol or high low-density lipoprotein (LDL) cholesterol is associated with atherosclerosis, which increases a person’s risk for CAD.

The Healthy People 2020 target is a mean population total cholesterol (TC) level of 177.9 mg/dL for adults, which has not been met. Conversely, the Healthy People 2020 target of ≤13.5% for adults with high total cholesterol (TC) of ≥240 mg/dL has been achieved from the period from 2015 to 2018 for adults, including all race-sex subgroups. Approximately 28.5 million people ages 20 and older have a high serum total cholesterol level of ≥240 mg/dL (Virani et al., 2021).

Cholesterol level is affected by:

• Age
• Gender (women have higher prevalence of high TC than males)
• Heredity
• Ethnicity (higher cholesterol predominantly in Black and Hispanic individuals)
• Diet

Genetic factors, type 2 diabetes, and certain drugs, such as beta blockers and anabolic steroids, also lower HDL cholesterol levels. Smoking, being overweight, and being sedentary can all result in lower HDL cholesterol (Virani et al., 2021).

ATP III CHOLESTEROL CLASSIFICATIONS

LEVEL (mg/dL)	CLASSIFICATION
(Cleveland Clinic, 2020)
LDL Cholesterol (Primary target of therapy)
<100	Optimal
100–129	Near optimal/above optimal
130–159	Borderline high
160–189	High
≥190	Very high
HDL Cholesterol
<40	Low
≥60	High
Total Cholesterol
<200	Desirable
200–239	Borderline high
≥240	High

HYPERTENSION

Hypertension (HTN) causes inflammation, which can damage the lining of arteries and increase fatty deposits, contributing to the development of atherosclerosis and CAD. For people at increased risk for CAD, blood pressure control is an important factor. A diagnosis of HTN is confirmed when two or more elevated blood pressure readings are obtained on separate visits.

BLOOD PRESSURE READINGS (in mm/Hg)

Category	Systolic	Diastolic
(AHA, 2021c)
Normal	<120	and <80
Elevated	120–129	and <80
Hypertension stage 1	130–139	or 80–89
Hypertension stage 2	≥140	or ≥90
Hypertensive crisis	>180	and/or >120

The prevalence of HTN or those taking antihypertensive medications is 7.5% among those ages 18–39 years, 33.2% among those ages 40–59 years, and 63.1% among those ages 60+ years. HTN is a comorbidity in many other diseases and conditions, including diabetes, CAD, heart failure, obesity, and renal failure. Essential hypertension is the primary cause of 32.8 million visits to physicians’ offices and 1.1 million emergency department visits every year.

There are distinct differences in the prevalence of HTN among different ethnicities. Black men and women in the United States have the highest occurrence of hypertension in the world. Black Americans experience HTN much earlier than Whites and measure much higher blood pressures. HTN incidence is:

• 40.6% and 39.9% among non-Hispanic Black males and females
• 29.7% and 25.6% among non-Hispanic White males and females
• 28.7% and 21.9% among non-Hispanic Asian males and females
• 27.3% and 28% among Hispanic males and females
  (CDC, 2021b)

Treating hypertension is an important factor in preventing CAD and includes the following strategies:

• Lifestyle modifications, such as smoking cessation, exercise, weight loss, and dietary changes.
• Medications to control blood pressure, such as beta blockers, calcium channel blockers, angiotensin receptor blockers, and thiazide diuretics. U.S. adults who are treated with prescription pharmacological means for HTN achieve increased blood pressure control in 70.4% of all cases.
  (CDC, 2021b)

PHYSICAL INACTIVITY

A sedentary lifestyle is a risk factor for CAD. Patients with a sedentary lifestyle are also more likely to be overweight, obese, or hypertensive, which contributes to the risk of developing CAD. While the frequency of U.S. adults engaging in measurable physical activity has improved in the last several years, a 2018 study, the Physical Activity Guidelines for Americans, found that only 24.0% of adults reported participating in adequate aerobic and muscle-strengthening activity to meet U.S. recommendations (Piercy et al., 2018).

The benefits of physical activity are well-established in many diverse studies. Even low levels of exercise (up to 75 minutes of brisk walking per week) were associated with a reduced risk of mortality in patients with CAD. Time in sedentary behavior is associated with a higher risk of mortality regardless of the underlying pathophysiology (Virani et al., 2021).

Patient goals for physical activity should begin with 10–15 minutes per day and gradually work up to a goal of 30 minutes per day of moderate to vigorous exercise. The more vigorous the activity, the greater the benefits. The level of activity is based on the patient’s baseline condition and other comorbid diseases. Patients should always work with their healthcare provider prior to starting an exercise program.

The cardiovascular benefits of exercise include a positive impact on:

• Lipid metabolism, by increasing HDL
• Blood pressure
• Insulin sensitivity, causing a reduction in blood sugar
• Reduced risk for metabolic syndrome
• Calories burned
• Strengthened bones and muscles
• Improved memory
• Improved mood
• Promoting sleep
• Reduced risk for some cancers
  (CDC, 2021c)

Although a program of regular exercise does not typically reduce LDL cholesterol levels to a significant degree, it will reduce insulin resistance and blood levels of triglycerides, and it will also increase blood levels of HDL cholesterol.

For patients who are just beginning an exercise program, it is important to start slowly and consult a professional, such as an exercise physiologist, for assistance in developing a plan that will work for them. For high-risk patients with comorbidities who are deconditioned or have had recent cardiac events, careful supervision of physical rehabilitation is recommended. Referral to a physical therapist to evaluate, plan, and monitor the patient’s progress with his or her exercise program is an important consideration.

OBESITY

Obesity increases the risk for heart disease by causing the heart to work harder. This increases the resistance against which the left ventricle must pump blood, leading to hypertension. With obesity, high blood cholesterol and triglyceride levels also increase, while HDL levels decrease. Obesity is defined as a body mass index (BMI) (weight in kg divided by the height in meters squared) of ≥30 kg/m², occurring in 39.9% of males and 41.1% of females. Extreme obesity indicates a BMI >40 kg/m² is 6.2% in males and 10.5% in females, the overall prevalence of obesity among youth 2 to 19 years of age is 19.0% of the U.S. adult population (Virani et al., 2021). Patients who have a larger waist measurement than hip measurement are at increased risk for CAD.

The incidence of most cardiovascular diseases, including CAD, are increased in the setting of obesity. Patients who are obese are also at increased risk for developing some cancers, osteoarthritis, metabolic syndrome, and diabetes.

Obesity usually results as an imbalance between caloric intake and expenditure. Diets of obese persons usually have an increase in energy-dense foods that are high in fat and carbohydrates. There is also usually an increase in physical inactivity due to the sedentary nature of many forms of work, changing modes of transportation to the more passive, and increasing urbanization. Referral to a dietitian may be indicated to assist patients with meal planning and monitoring.

Treatment for obesity should include:

• Limiting energy intake from total fats and carbohydrates
• Increasing the amount of fruits, vegetables, legumes, whole grains, lean proteins, and nuts
• Engaging in regular physical activity (60 minutes a day for children and 150 minutes spread through the week for adults)
  (WHO, 2021)

Even a modest weight loss makes a difference. Patients who are overweight should be encouraged to follow a comprehensive weight-loss plan. A goal of achieving a 10% weight loss will lower a person’s risk for CAD. A small but consistent weight loss of 1/2 to 2 pounds per week is the safest way to accomplish this.

DIABETES MELLITUS

Diabetes is a strong risk factor for developing CAD; the two diseases often coexist. Even when glucose levels are under good control, diabetes increases the risk of heart disease and stroke. The risks are even greater if blood sugar is not well controlled.

In the United States, an estimated 26 million adults have been diagnosed with diabetes mellitus (DM), 9.4 million have undiagnosed DM, and 91.8 million have prediabetes. A blood hemoglobin A1C ≥6.5% is the threshold used to diagnose DM. With DM, age-adjusted cardiovascular disease prevalence was higher among males than among females, among Whites than Blacks, and among non-Hispanics than Hispanics. At least 68% of people >65 years of age with DM die of some form of heart disease (Virani et al., 2021).

Patients with type 2 DM may have an increased risk of CAD because of shared risk factors such as age and gender; anthropometric (measurement and proportion), metabolic, socioeconomic, and lifestyle variables; psychosocial stress; environmental pollutant exposure; and disturbances in protein and fat metabolism, which may lead to weight problems. As a result, most patients with type 2 diabetes are overweight or obese. Maintaining a normal weight with diet and exercise as well as taking prescribed medications is important to maintain adequate blood sugar control (CDC, 2021d).

Physical exercise significantly improves glucose tolerance and insulin resistance. The benefits of exercise show that higher fitness is associated with a lower risk of incident DM regardless of demographic characteristics and baseline risk factors.

METABOLIC SYNDROME

According to the International Diabetes Federation, the NHLBI, and the AHA, metabolic syndrome is diagnosed when a patient exhibits three of the following risk factors:

• Fasting plasma glucose ≥100 mg/dL or undergoing drug treatment for elevated glucose
• HDL-C <40 mg/dL in males or <50 mg/dL in females or undergoing drug treatment for reduced HDL-C
• Triglycerides ≥150 mg/dL or undergoing drug treatment for elevated triglycerides
• Waist circumference >102 cm in males or >88 cm in females for people of most ancestries living in the United States (Ethnicity and country-specific thresholds can be used for diagnosis in some groups, particularly Asians and individuals of non-European ancestry who have predominantly resided outside the United States.)
• BP ≥130 mmHg systolic or ≥85 mmHg diastolic or undergoing drug treatment for hypertension, or antihypertensive drug treatment in a patient with a history of hypertension

Metabolic syndrome is linked to several related disorders, including nonalcoholic fatty liver, sexual/reproductive dysfunction (erectile dysfunction in men and polycystic ovarian syndrome in women), obstructive sleep apnea, certain cancers, and osteoarthritis, as well as general proinflammatory and prothrombotic tendencies (AHA, 2021g).

OTHER RISK FACTORS

CAD is a multifaceted disease with more than 250 recognized psychosocial, nutritional, genetic, and metabolic risk factors.

Stress may be a contributing factor for developing CAD. For example, stress may cause people to overeat, start smoking, or smoke more than they otherwise would. Psychosocial stress causes inflammation due to an increase in stress hormones that promotes the production of atherosclerosis. Certain types of adversity or trauma are linked to increased occurrence and worse CAD. Some examples of these are childhood trauma, sexual or physical abuse, type A and D personalities, job stress including overtime, depression, and anxiety (Bagheri et al., 2016).

Alcohol/substance abuse is also a risk factor. Drinking too much alcohol can raise blood pressure and contribute to high triglycerides. Alcohol and recreational drug use contribute to cardiovascular disease development, including CAD, ranging from subclinical atherosclerosis to fatal acute coronary syndromes. However, the risk of heart disease in people who drink moderate amounts of alcohol (i.e., one drink per day for women, two drinks per day for men) is lower than in nondrinkers.

Elevated total homocysteine (tHCY) levels pose an increased risk of cardiovascular disease by causing abnormal endothelial cell function and thrombosis. HCY lowering can be achieved by combining folate ingestion with vitamin B supplementation. Higher than normal tHCY levels are also prognostic of an increased risk of death, particularly in the case of NSTEMI.

Plasma homocysteine is a nonprotein amino acid that contains sulfur. HCY is directly associated with cardiovascular diseases such as CAD, hypertension, acute MI, and aortic atherosclerosis. Elevated HCY levels are also related to cardiac dysrhythmias such as recurrence of atrial fibrillation after cardioversion, prolonged QT intervals, and p-wave dispersion as a precursor for newly occurring atrial fibrillation (Medline Plus, 2020).

Nutrition is also an important factor. Eating habits can affect other controllable risk factors such as cholesterol, blood pressure, diabetes, and weight. Evidence has shown that including a diet rich in vegetables, fruits, whole-grain and high-fiber foods, fish, lean protein, and fat-free or low-fat dairy products may lower a person’s risk for developing CAD. AHA guidelines place emphasis on foods and an overall eating pattern rather than on percentages of food components such as fat (see box below).

The average U.S. adult caloric consumption is 2,500 calories for men and 1,800 calories for women. Dietary habits affect multiple cardiovascular risk factors, including both established risk factors (e.g., systolic blood pressure, diastolic blood pressure, LDL-C levels, HDL-C levels, glucose levels, and obesity/weight gain) and novel risk factors (e.g., inflammation, cardiac arrhythmias, endothelial cell function, triglyceride levels, lipoprotein(a) levels, and heart rate)

.