Causes and Risk Factors of Heart Disease

Because heart disease is a general term for a number of different conditions, the cause of your case depends on the type you have. The bad news about heart disease is that it remains extremely prevalent in our society—it's the leading cause of death for both men and women in the United States. The good news is that many of the factors that determine your risk of developing heart disease are, to a large extent, under your control.

Common Causes

The causes of heart disease depend on the general type you have.

Atherosclerotic Disease

Atherosclerosis, a condition in which plaque builds up and hardens in your arteries, blocking and narrowing the passages, can lead to atherosclerotic diseases such as coronary artery disease, peripheral artery disease, and carotid artery disease. Though the exact cause of atherosclerosis isn't known, there are factors that can lead to artery damage, which can then lead to plaque building up where the damage occurs.

Plaque is made up of fat, cholesterol, calcium, and other substances. If plaque build-ups rupture, this can lead to blood clots, which make the arteries even more narrow and can lead to problems like angina (chest pain), heart attack, stroke, and transient ischemic attacks (TIAs).

Cardiac Arrhythmias

Cardiac arrhythmias are abnormal heart rhythms, whether too fast, too slow, or irregular. Common causes of arrhythmias include:

• Heart defects that you're born with (congenital)
• Coronary artery disease (a type of atherosclerotic disease)
• High blood pressure
• Diabetes
• Heart valve disease
• Certain medications, including over-the-counter medicines, herbal remedies, and prescription medications
• Smoking
• Drinking alcohol or caffeine in excessive amounts
• Drug use
• Stress

Heart Valve Disease

Heart valve disease has many causes. While it can result from infectious endocarditis or rheumatic heart disease, valvular heart disease is more commonly caused by heart dilation (or cardiac remodeling), calcium deposits on the valves that may occur with aging, and congenital cardiac problems.

Any of the four heart valves can develop either stenosis or regurgitation. A bicuspid aortic valve is the most common congenital heart valve problem. Among adults, the most common types of significant heart valve disease are aortic stenosis, aortic regurgitation, mitral stenosis and mitral regurgitation. The most commonly diagnosed heart valve problem in adults is mitral valve prolapse (MVP), but the large majority of people who are diagnosed with MVP have a very mild form that will never cause significant heart problems.

Heart Infections

A heart infection is caused by a bacterium, virus, parasite, or chemical getting into your heart muscle. This can occur when microbes from your mouth or elsewhere in your body get into your bloodstream and attach to the damaged areas of your heart. It can also happen when a microbe gets into your body through a break in your skin from surgery or drug use. The resulting infection is usually fairly mild, but it sometimes becomes serious. Areas of your heart that can become infected and inflamed include the chamber and valves (endocarditis), the protective sac around your heart (pericarditis), and the muscular layer of your heart (myocarditis).

Heart Failure

The most common cause of heart failure is cardiomyopathy, a condition in which there is an abnormality in the heart muscle. Dilated cardiomyopathy, which is characterized by a prominent enlargement, thinning, and stretching of the left ventricle, is the most common type of cardiomyopathy. The exact cause of dilated cardiomyopathy is unknown, but it may be due to damage to the heart that results in less blood flow. You can either be born with this heart defect or it can result from things that cause thinning and stretching of the left ventricle, including drug use, a heart infection, an alcohol use disorder, a heart attack, or other types of heart disease like high blood pressure and arrhythmias.

Hypertrophic cardiomyopathy is usually due to a genetic disorder of the heart that produces a thickening (hypertrophy) of the heart muscle. It can produce several kinds of cardiac problems, including heart failure. The severity of hypertrophic cardiomyopathy varies tremendously from person to person and is related to the specific genetic variant (of which there are many) that is producing it. This type of cardiomyopathy can also occur over time from high blood pressure or aging.

Restrictive cardiomyopathy, which causes the heart to become stiff and rigid, is the least common type. It can happen for no reason or it can be caused by conditions such as connective tissue disorders, a buildup of iron or protein in your body, and by certain treatments for cancer.

Other conditions that can weaken and damage your heart, leading to heart failure, include:

• Coronary artery disease
• Heart attack
• High blood pressure
• Damaged heart valves
• Myocarditis, a heart infection
• Congenital heart defects
• Heart arrhythmias
• Chronic diseases like diabetes, thyroid disease, and HIV
• Too much iron or protein in your body

Acute (sudden) heart failure can be caused by:

• Viruses that attack the heart
• Allergic reaction
• Blood clots in your lungs
• Severe infections
• Certain medications
• Illnesses that affect your entire body

Genetics

There are many inherited heart diseases or conditions that affect your heart, including:

• Arrhythmogenic right ventricular cardiomyopathy: This inherited disorder causes the muscle tissue in your heart to die and be replaced by fatty, scar tissue. ARVD is rare, but it can cause arrhythmias, heart failure, and sudden cardiac death in young people.
• Brugada syndrome: This is a family of inherited cardiac arrhythmias. In people who have one of the forms of Brugada syndrome, dangerous arrhythmias can be triggered by various drugs and electrolyte imbalances. In this syndrome, there's a defect in the channels where your heart's electrical activity takes place, leading to potentially life-threatening heart arrhythmias.
• Cardiac amyloidosis: This is a type of restrictive cardiomyopathy in which the heart becomes stiff and rigid because of protein clumps replacing normal heart tissue. It can be inherited, but it can also be caused by other diseases.
• Cardiac myxoma: This noncancerous heart tumor is inherited in around 1 in 10 cases. It can cause heart arrhythmias, block blood flow, and lead to an embolism, in which tumor cells break off and travel through the bloodstream.
• Familial dilated cardiomyopathy: While many causes of dilated cardiomyopathy are unknown, up to one-third of people who develop this condition inherit it from their parents, known as familial dilated cardiomyopathy.
• Familial valvular heart disease: Valve disorders and defects can be congenital, meaning you're born with them, due to gene mutations. The most common congenital valve abnormalities are the bicuspid aortic valve, mitral valve prolapse, pulmonary valve stenosis, and Ebstein anomaly of the tricuspid valve.
• Hypertrophic cardiomyopathy: This type of cardiomyopathy is usually inherited due to a change in the genes of the proteins in your heart muscle that causes it to thicken.
• Long QT syndrome: This abnormality in the heart's electrical system is usually inherited, but can also be caused by drug use, and can produce a severe arrhythmia that causes fainting or sudden death.
• Loeyz-Dietz syndrome: This genetic disorder causes the aorta, the blood vessel through which blood flows from the heart to the rest of the body, to become enlarged. This can stretch and weaken it, resulting in an aneurysm, a bulge in the aortic wall, as well as tears in the wall. People with this syndrome are often born with heart defects like an atrial septal defect, patent ductus arteriosus, or bicuspid aortic valve.
• Marfan syndrome: This genetic disorder affects the aorta in the same way as Loeyz-Dietz syndrome. The two syndromes can be distinguished by the different gene mutations they each have.
• Familial hypercholesterolemia: This inherited disorder, which is caused by a chromosomal defect, begins at birth and results in extremely high LDL cholesterol (the "bad" type), putting you at high risk of developing atherosclerosis. Heart attacks at a young age can occur as a result.

Lifestyle Risk Factors

Most of the risk factors for heart disease involve your lifestyle choices. This means that you can lower your chances of developing heart disease by pinpointing the areas that put you at risk and taking steps to change them.

• Smoking: Smokers are more likely to develop atherosclerosis and have heart attacks. This is because carbon monoxide can damage the lining of your blood vessels and nicotine raises your blood pressure. Being around other people's smoke can also increase your risk of developing heart disease.
• Unhealthy diet: A diet that's high in fat, sugar, and cholesterol can contribute to developing heart diseases like atherosclerosis. Consuming too much salt can lead to high blood pressure. Eating a diet that's rich in fruits, vegetables, and whole grains can help reduce your risk.
• Obesity: Being obese increases your risk of heart disease because it leads to other risk factors such as high cholesterol, diabetes, and high blood pressure.
• Sedentary lifestyle: Regular exercise lowers your risk for heart disease in part by helping to keep your cholesterol lower, your diabetes controlled, your weight down, and (for some people) blood pressure lower.
• Excessive alcohol consumption: Drinking too much alcohol can result in raised blood pressure and it increases your cholesterol level, which can lead to atherosclerosis. It can also cause heart arrhythmias, stroke, and cardiomyopathy. Limit your alcohol consumption to two drinks a day for men and one drink a day for women.
• Stress: The exact relationship between stress and heart disease is still being studied, but excessive and prolonged stress definitely contributes to long-term illnesses like high blood pressure. Stress may also influence your behavior and the lifestyle risks you take that contribute to heart disease. For instance, you may drink more alcohol and/or smoke when you're under stress, both known contributors to developing heart disease.
• Poor hygiene: When you don't regularly wash your hands, you're more at risk for picking up bacteria and viruses that can lead to a heart infection, particularly if you already have a heart condition. Poor dental hygiene can also lead to heart disease, especially heart infections.

Other Risk Factors

There are some risk factors that you have no control over, including:

• Age: As you get older, your heart muscle may get weaker and/or thicker and your arteries may become damaged. Most people who die from heart disease are age 65 or older.
• Sex: Men have a higher risk of having a heart attack than women do and they're more at risk to develop heart disease. Women's risk increases after menopause but is still lower than men's.
• Heredity: If you have a family history of heart disease, your risk is greater, especially if it involves one or both of your parents and diagnosis was made before the age 55 in a man or before age 65 in a woman.
• Race: African Americans, Mexican Americans, Native Americans, Native Hawaiians, and some Asian Americans have higher rates of heart disease.

Certain treatable medical conditions can also increase your risk of heart disease, including:

• High blood pressure: When the pressure in your arteries and blood vessels is too high, it causes high blood pressure, which, if uncontrolled, can lead to your arteries thickening and hardening. There are often no symptoms, so it's important to get your blood pressure checked periodically since it can be controlled with medication and/or lifestyle changes.
• High cholesterol: When you consume more cholesterol than your body can use, it builds up in your artery walls, including the arteries in your heart. This can cause your arteries to narrow and atherosclerosis to occur, decreasing blood flow to your heart and other organs. Cholesterol can also be elevated due to the body producing too much cholesterol or the body not adequately getting rid of cholesterol. Like high blood pressure, high cholesterol can also be treated with lifestyle modifications and/or medication.
• Diabetes: Even when your blood sugar levels are under control, your risk of heart disease and stroke is higher than that of the general population, especially if your diabetes is poorly controlled. The risk of death from heart disease is also much higher in people who have diabetes. It's important to make sure that your blood sugar level is well-controlled and that your healthcare provider is monitoring your heart health closely as well, especially as you get older.

Keep in mind that your chance of developing heart disease increases with each additional risk factor that applies to you, so work with your healthcare provider to keep these medical conditions treated and under control.

Heart Disease Doctor Discussion Guide

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Determining Your Risk

If your healthcare provider has not performed a formal cardiac risk assessment, you should estimate your risk yourself. If your risk appears to be intermediate or high, you need to talk to your healthcare provider about taking aggressive measures to prevent heart disease. To assess your own risk of heart disease, you need to consider the following information:

• Smoking history
• Your total and HDL cholesterol levels
• Your blood pressure
• Whether you have evidence of diabetes or metabolic syndrome
• Whether you are overweight for your age and height
• Whether close relatives have had premature heart disease

With this information, you can place yourself into one of three categories: low, intermediate, or high. Of course, if you believe you are at risk and have trouble performing this assessment yourself, speak with your healthcare provider about your concern and ask that he or she assist you.

Low-Risk Category

All of the following must be present:

• Nonsmoker
• Total cholesterol less than 200 mg/dL, HDL cholesterol greater than 40 mg/dL
• Systolic blood pressure less than 120, diastolic blood pressure less than 80
• No evidence of diabetes
• Not overweight
• No family history of premature cardiovascular disease

If you are at low risk, you don't need any special medical interventions to reduce your risk, except perhaps for routine coaching on maintaining a healthy lifestyle. About 35 percent of American adults fall into this category.

High-Risk Category

You're at high risk if any of the following apply to you:

• Known coronary artery disease or another vascular disease
• Type 2 diabetes
• Over age 65 with more than one risk factor

If you're in the high-risk group, this means one of two things: Either your risk of developing heart disease within the next few years is quite high, or you already have heart disease and are unaware. Unfortunately, a substantial proportion of people who learn they're in the high-risk category turn out to already have significant coronary artery disease (CAD). They just don't know about it because, so far, they aren't having symptoms.

Intermediate Risk Category

You're in this group if you don't fit into either the low- or high-risk groups.

If you're in this group, you should take aggressive steps to modify the risk factors keeping you out of the low-risk category. Also, you should discuss with your healthcare provider whether further testing should be done to characterize your risk more accurately. Such testing might include having your C-reactive protein (CRP) level measured and getting a calcium scan.