Heart Problems
Cardiotoxicity — heart damage caused by treatment — is an unfortunate side effect of some breast cancer treatments. Chemotherapy and certain targeted therapy medicines are the most common causes. Heart problems can happen during or after treatment.
Cardiotoxicity symptoms
The symptoms of cardiotoxicity may include:
heart palpitations (rapid or fluttering heartbeat)
abnormal heart rhythm (your heart beating irregularly)
chest pains
heart attack
stroke
swelling in feet or legs caused by a build-up of fluid
shortness of breath or other breathing problems
If you have any of these symptoms, call your doctor immediately. Since heart problems also can be caused by other things, including stress and smoking, it's important to figure out exactly what's happening.
Breast cancer treatments that can cause heart damage
You may be at higher risk of heart damage if you’ve received these treatments for breast cancer.
Many chemotherapy medicines are linked to cardiotoxicity, but anthracyclines — including Adriamycin (chemical name: doxorubicin), Doxil (chemical name: doxorubicin), and Ellence (chemical name: epirubicin) — are especially known to cause heart damage.
Several targeted therapy medicines are known to cause heart damage, especially Herceptin (chemical name: trastuzumab) and medicines that have Herceptin as an ingredient. These include Enhertu (chemical name: fam-trastuzumab-deruxtecan-nxki), Herceptin Hylecta (chemical name: trastuzumab and hyaluronidase-oysk), Kadcyla (chemical name: T-DM1 or ado-trastuzumab emtansine), and Phesgo (chemical name: pertuzumab, trastuzumab, and hyaluronidase-zzxf).
Tykerb (chemical name: lapatinib), which is sometimes used to treat HER2 positive breast cancer, also can cause cardiotoxicity.
Kisqali (chemical name: ribociclib), a type of targeted therapy called a CDK4/6 inhibitor, can cause QT prolongation, which means the heart beats quickly and irregularly.
Results of a 2025 study suggest that removing the ovaries before menopause is linked to heart failure later in life. The results also suggest that the younger someone is when the procedure is done, the higher the risk of heart failure. Prophylactic ovary removal is one step women with a higher-than-average risk of breast cancer can take to lower their risk of the disease.
In the past, radiation to the chest was known to cause heart damage. But advances in how radiation therapy is delivered have greatly reduced the amount of radiation the heart is exposed to.
Long-term cardiotoxicity
A 2024 study found that people who received an anthracycline medicine or Herceptin to treat breast cancer had a higher long-term risk of cardiomyopathy — a disease of the heart muscle that makes it hard for the heart to pump blood — and heart failure than people who didn’t receive these medicines. The increased risk was even higher in people diagnosed before age 55.
This is why it’s important to make sure you have good follow-up care after active breast cancer treatment ends. This includes a customized follow-up care plan, based on your unique needs, age, diagnosis, and treatments. If you’ve received any medicines that could damage your heart, it’s a good idea to talk to your doctor about having regular cardiac tests to monitor your heart function.
Heart tests
If you receive any treatments known to affect your heart, your doctor will check your heart function at several points: before you start treatment, during treatment, and after treatment is completed.
Treating cardiotoxicity
If tests show you have any type of heart damage during treatment, your doctor will likely lower the dose of medicine. You also may have to take a break from treatment or stop that treatment altogether. If you’ve completed treatment and notice any symptoms of heart problems, see your doctor right away. There are medicines that can help.
There are also lifestyle changes you can make to keep your heart as healthy as possible during and after breast cancer treatment:
Eat a healthy diet full of fruits, vegetables, whole grains, and low-fat dairy products. Reduce the amount of fatty meat and sugar you eat.
Exercise. Regular exercise can help you maintain a healthy weight, reduce stress, and keep your heart (a muscle) fit. A 2025 study found that each additional 2,500 steps per day taken by women with a history of cancer was linked to a 34% lower risk of dying from heart disease.
Stop smoking. The chemicals in cigarettes are damaging to the heart.
Keep a healthy weight. If you're overweight, your heart has to work harder. Excess weight also raises your risk of high blood pressure, diabetes, and high cholesterol, all of which can harm your heart.
Manage high blood pressure, if you've been diagnosed with it. This includes taking medicine, eating a healthy diet, and exercising.
Try to reduce your stress levels. Relaxation techniques such as meditation and guided imagery can help, as can exercise, spending time in nature, and being around people who make you laugh.
Have regular cholesterol screenings and manage your levels if they’re high. Changes to your diet can help lower the amount of "bad" cholesterol (low-density lipoproteins) and increase the amount of "good" cholesterol (high-density lipoproteins) in your blood.
— Last updated on August 18, 2025 at 3:01 PM
