A condition known as cardiomyopathy

By Shamard Charles, MD, MPH 

 Medically reviewed by Jeffrey S. Lander, MD

A weak heart muscle (cardiomyopathy) can be caused by conditions like diabetes, coronary heart disease, and high blood pressure. When the heart is weak, it's often unable to either fill up properly (heart failure with preserved ejection fraction) or pump efficiently (heart failure with reduced ejection fraction).

This leads to reduced blood flow throughout the body, meaning organs and tissues—including the heart—don't get an adequate supply of oxygen and vital nutrients.

This article discusses weak heart symptoms, causes, and when it is time to see a healthcare provider.

Weak Heart Muscle Symptoms and Signs

In a healthy heart, blood is pumped from the right side of the heart to the lungs, where it picks up oxygen. The oxygen rich blood then travels from the lungs to the left side of the heart, where it is pumped out to the rest of the body.

When the heart is weakened, it tries to compensate by pumping even faster. Over time, this stretches or thickens the heart muscle, both of which can further weaken it.

Reduced blood flow to the kidneys is a particular concern, as it impairs their ability to regulate the excretion of fluids from the body. This leads to fluid retention and the buildup of fluids in the limbs, thorax (chest cavity), and lungs.

This can lead to an array of symptoms associated with a weak heart, including:1

• Shortness of breath with activity or even at rest

• Peripheral edema (swelling of the legs, ankles, and feet)

• Ascites (abdominal bloating of to fluid buildup)

• Rapid, pounding, or fluttering heartbeat

• Chest pressure or discomfort

• Coughing while lying down

• Difficulty lying flat to sleep

• Chronic fatigue

• Dizziness, lightheadedness, or fainting

Causes

Narrowing of the arteries, high blood pressure, obesity, and lifestyle factors like smoking are a few of the possible causes of a weak heart. Sometimes, more than one condition may be at play.

The body's ability to compensate for the effects these have on the heart may be beneficial initially, but the adaptations often contribute to the most serious cases of heart failure in the long run.

Lifestyle

Lifestyle factors are an important cause of a weakening heart. This also means that heart disease may be preventable for many people.

A sedentary lifestyle, heavy alcohol use, and poor diet put strain on the heart. As pressure builds up, the heart muscle can thicken and lose its ability to pump effectively.

Smoking is particularly noteworthy. The carcinogenic chemicals in cigarette smoke not only damage the lungs, which are integral to the cardiac cycle, but also the heart muscle, increasing your risk of cardiovascular disease.

In addition, chemicals in cigarette smoke change your blood chemistry, leading to changes such as blood vessel narrowing and plaque formation. These can permanently damage your heart and blood vessels.2

The impact of your lifestyle on your heart health is complex and multifactorial in nature. For example, cigarette smoke not only weakens the heart muscle directly, but narrows the arteries. Smoking is also associated with obesity and high blood pressure, other causes of a weak heart.3

Narrowing of the Arteries

Hardening and narrowing of the arteries (atherosclerosis) is when cholesterol and other substances build up in the walls of arteries and form hard material called plaques.

Coronary artery disease (CAD) is the result of severe atherosclerosis and can become more problematic when the blood that is pumped out of the heart is not enough to support bodily functions.

Over time, CAD can weaken the heart muscle and contribute to heart failure and arrhythmias.4

High Blood Pressure

High blood pressure (hypertension) forces your heart to work harder to pump blood. More forceful pumping of the heart leads to a thickening of the muscle, specifically the left ventricle, which can increase your risk of:

• Arrhythmias

• Heart failure

• Heart attack

• Sudden cardiac death

Sustained blood pressure above 120/80 mmHg for adults also narrows the arteries and enlarges the heart, compromising the structural integrity of the heart muscle.

An enlarged and weakened heart cannot pump blood efficiently throughout the body, making it impossible to meet the body’s demands.

Obesity

Obesity increases cardiovascular risk because the body requires more blood to supply oxygen and nutrients to vital tissues and organs. In order to meet this need, the body increases blood pressure.

Obesity is also associated with several medical conditions that put you at higher risk of heart disease, including:

• Hypertension

• Diabetes

• Coronary artery disease

• Sleep apnea syndrome

Obesity may also increase atherosclerosis and contribute to structural and functional changes of the heart, which weaken the heart. The altered structure increases the risk of atrial fibrillation and sudden cardiac death.5

Some studies have shown that overweight and mild levels of obesity may have a protective effect on the clinical outcome of some underlying cardiovascular diseases, a phenomenon called the obesity paradox. However, the dangers of obesity far outweigh any purported benefit.5

Congenital Heart Defects

Congenital heart defects are structural problems of the heart that are present at birth and may change the way the heart works.

A normal heart has valves, arteries, and chambers that circulate blood in a cyclical pattern: body to heart, heart to lungs, lungs to heart, and then heart out to the body.

When this is thrown off, it can cause the underdeveloped heart to change shape and function less efficiently. Pressure can build, and the heart muscle can weaken and fail as a result.6

Congenital heart defects range in severity from small holes between chambers to the complete absence of one or more chambers or valves. The greater the severity of the malformation, the greater the likelihood of developing a weakened heart and long-term complications.

Chemotherapy

Certain types of chemotherapy treatments can contribute to a weakened heart. These medications can cause the left chamber of the heart to become enlarged, limiting its ability to pump blood.7

Chemotherapy medications that may cause a weak heart include:7

• Anthracyclines, which are used to treat leukemia and cancers of the breast, stomach, lungs, uterus, and more

• Herceptin (trastuzumab), which is used to treat breast cancer

• Certain types of immunotherapy, such as immune checkpoint inhibitors, which are used to treat cancers like melanoma8

These drugs are more likely to cause a weakened heart in people who have a history of heart issues. If chemotherapy is contributing to cardiomyopathy, a healthcare provider may recommend altering your treatment regimen.7

When to See a Healthcare Provider

Signs and symptoms of a weakened heart may be subtle and easily missed. They can also be inadvertently associated with a more benign condition and even normal aging.

Seek medical attention if you experience any of the aforementioned symptoms.
Even if your symptoms do not signal immediate danger, they may be a warning sign of a larger problem down the line.

If you wait until you experience obvious symptoms of heart failure before seeing a healthcare professional, the condition may already be life threatening.

Treatment for a Weak Heart

Treating the underlying cause of your weak heart is the best way to mitigate symptoms and improve your activity level. Treatment options include:

• Engaging in regular low-intensity aerobic exercise to strengthen the heart

• Eating a heart-healthy diet

• Cutting back on salt (sodium)

• Limiting alcohol consumption

• Quitting smoking (and cutting back until the habit is kicked)

The use of one or several medications aimed at reducing the fluid load on the heart may further help. These include:9

• Diuretics, which help reduce fluid buildup in the body

• Angiotensin-converting enzyme (ACE) inhibitors, which help lower blood pressure and reduce strain on the heart. If you cannot tolerate ACE inhibitors, angiotensin receptor blockers (ARBs) may be used in their place.

• Beta-blockers, to reduce heart rate and blood pressure

• Angiotensin-receptor neprilysin inhibitors (ARNIs), which are a combination of an ARB inhibitor and an agent called sacubitril, can help regulate blood pressure, as well as salt and fluid levels.

• Aldosterone antagonists (such as spironolactone or eplerenone) can help remove excess fluid from the body.

• Sodium-glucose co-transporter 2 inhibitors (SGLT-2s), which are a treatment for diabetes but can also improve outcomes in people with heart failure

• Corlanor (ivabradine), to reduce heart rate

• Lanoxin (Digoxin), which lowers heart rate and strengthens heart contractions

Prevention

Because genetics may play a role in heart health, some people may not be able to completely prevent a weak heart. Still, creating heart-healthy habits can help everyone reduce their chances of developing cardiomyopathy.

Control Blood Pressure

The goal of a heart-healthy lifestyle is to keep your blood pressure around 120/80 mmHg. This ensures that your heart is not overworking itself.

Maintaining healthy blood pressure also lowers the risk of the following:10

• Stroke

• Kidney failure

• Vision loss

• Sexual dysfunction

• Angina due to coronary artery disease

Eat a Healthy Diet

Eating a balanced diet that is full of fruits and vegetables, whole grains, nuts, fish, poultry, and vegetable oils is the best way to prevent heart disease.

Limiting red meat, refined carbohydrates, highly processed foods, and alcohol also goes a long way in keeping your heart healthy.

Studies have shown that the Mediterranean diet and plant-based diets—which are high in whole grains, vegetables, fruits, legumes, and nuts—are particularly heart-healthy and lower the risk of heart disease by as much as 20%.11

Maintain a Healthy Weight

Some studies have found that waist size and excess weight—markers of obesity—are the biggest risk factors for coronary artery disease.5

Exercise

Exercising keeps the heart strong and helps the blood to circulate optimally, counteracting the effects of aging on the cardiovascular system to some degree.12

The U.S. Preventive Services Task Force recommends 30 minutes of moderate-intensity physical activity five days a week to prevent heart failure.

Getting in regular physical activity has so many benefits, such as lowering the risk of:

• Heart disease

• Diabetes

• Stroke

• High blood pressure

• Osteoporosis

• Certain cancers

Not to mention, exercise has the added benefits of:

• Controlling stress

• Improving sleep

• Maintaining a healthy weight

• Reducing the likelihood of developing cognitive decline later in life 

Monitor Drug Interactions

While managing your symptoms of heart failure may require that you take more than one medication, several commonly used prescription drugs, over-the-counter medicines, and supplements can interact dangerously.

This can intensify heart failure symptoms and put you at risk of developing life-threatening complications.

To be on the safe side:

• Make sure all of your medical providers have a complete list of all the medicines you take.

• Do not begin a new medication without first checking in with a healthcare professional.

• Be mindful of the symptoms that may arise with each new medication. If you experience worsening or new symptoms, speak to your healthcare provider immediately.

Some common medications that may be problematic include:

• Nonsteroidal anti-inflammatory drugs (NSAIDs)—common over-the-counter painkillers like Advil and Motrin (ibuprofen)—can cause the body to retain sodium and fluid, worsening heart failure symptoms.

• Heartburn medicines and cold remedies contain sodium, which stimulates fluid retention. 

• Herbal remedies like ephedra, St. John’s wort, ginseng, hawthorn, black cohosh, and green tea can interact and lessen the effects of several common heart medications.

Summary

Many conditions can cause a weakened heart muscle, a condition known as cardiomyopathy. This impacts both blood flow to and out of the heart, depriving the body from oxygen and nutrients it needs to function properly.

You may not notice initial symptoms of a weak heart. But if you are feeling more fatigued than usual, unusual aches and pains, are lightheaded, or have chest pain, seek immediate medical attention.

Sources

Shu Q, Wu L, Zhang R, Zhang Q, Huang J, Meng Y. Age-dependent changes in cardiac performance, motor function, QoL, and mental status in metoprolol-treated chronic heart failure patients. Sci Rep. 2019;9(1):453. doi:10.1038/s41598-018-37520-8

U.S. Department of Health and Human Services. How tobacco smoke causes disease: the biology and behavioral basis for smoking-attributable disease.

Centers for Disease Control and Prevention. Adult obesity causes & consequences.

World Health Organization. Cardiovascular disease.

Csige I, Ujvárosy D, Szabó Z, et al. The impact of obesity on the cardiovascular system. J Diabetes Research. 2018;2018:1-12. doi:10.1155/2018/3407306

American Heart Association. The impacts of congenital defects. 

Memorial Sloan Kettering Cancer Center. About cardiomyopathy caused by chemotherapy.

Shalata W, Abu-salman A, Steckbeck R, Mathew Jacob B, Massalha I, Yakobson A. Cardiac toxicity associated with immune checkpoint inhibitors: a systematic review. Cancers. 2021;13(20):5218. doi:10.3390/cancers13205218

UpToDate. Patient education: heart failure (beyond the basics).

American Heart Association. Health threats from high blood pressure.

Shan Z, Li Y, Baden MY, et al. Association between healthy eating patterns and risk of cardiovascular disease. JAMA Intern Med. 2020;180(8):1090. doi:10.1001/jamainternmed.2020.2176

U.S. Preventive Services Task Force. Healthy diet and physical activity for cardiovascular disease prevention in adults with cardiovascular risk factors: behavioral counseling interventions.

By Shamard Charles, MD, MPH
Shamard Charles, MD, MPH is a public health physician and journalist. He has held positions with major news networks like NBC reporting on health policy, public health initiatives, diversity in medicine, and new developments in health care research and medical treatments.