Ask the Expert: Heart Health

February 1, 2017

Breast cancer treatments can save lives. But they can also have side effects. One serious potential side effect of some breast cancer treatments is heart damage. But you and your healthcare providers can take action to protect your heart.

In February, Living Beyond Breast Cancer expert Gretchen G. Kimmick, MD, MS answered your questions about heart health, including how different breast cancer treatments can affect your heart, how to keep your heart strong after a breast cancer diagnosis, and more. 

Remember: we cannot provide diagnoses, medical consultations or specific treatment recommendations. This service is designed for educational and informational purposes only. The information is general in nature. For specific healthcare questions or concerns, consult your healthcare provider because treatment varies with individual circumstances. The content is not intended in any way to substitute for professional counseling or medical advice.

I’ve had chemo, surgery, radiation, and targeted therapy for early-stage breast cancer and I’m worried about long-term heart issues. Should I be tested to be sure that no long-term damage has taken place?

If you had an anthracycline, such as doxorubicin (Adriamycin), or the targeted therapy trastuzumab (Herceptin), there is a small increased risk of weakening of the heart muscle, also called congestive heart failure (CHF). We generally monitor heart function during therapy with trastuzumab. If you have completed therapy and had one of these medicines, it would be reasonable to check heart function with an echocardiogram every 5 years.

But at this point there is no data to support that any monitoring is worthwhile, so your doctor may simply monitor for symptoms of decrease in heart function. Symptoms that would raise concern for CHF include swelling in the legs, inability to sleep flat on your back in bed, waking at night short of breath and having to sit up, decrease in exercise tolerance or shortness of breath.  

What effects can the chemotherapy medicine doxorubicin (Adriamycin) have on the heart? Should treatment with it be stopped after a certain amount of time to prevent heart problems?

Doxorubicin (Adriamycin) can cause injury to the heart muscle, which may lead to congestive heart failure (CHF). The higher the cumulative dose of doxorubicin, the higher the risk for CHF. In early-stage disease, we typically limit cumulative dose to less than 300 mg/m2. In settings where treatment is controlling incurable cancer, the balance between the treatment side effects and cancer’s side effects need to be carefully weighed. If the treatment is working and there are no symptoms of CHF, the benefits are outweighing the risks!  

What effect can radiation therapy have on the heart? Are there ways to make heart problems from radiation less likely?

If the heart is included in the area of the body being radiated, there can be scarring of the heart muscle and hardening of the arteries. The severity depends on the dose of radiation to the heart and the duration of time after the radiation. The risk is decreased by minimizing the heart’s exposure to radiation with newer radiation techniques, such as the “breath-hold” technique when radiation is given to the left breast to prevent cancer recurrence after breast conserving surgery.  

What kind of lifestyle changes should I make to strengthen my heart during and after breast cancer treatment?

At this point, we are still building evidence to support that lifestyle changes make a difference in side effects from breast cancer treatment. But lifestyle changes certainly make a difference to heart health in general. So, we suggest a healthy diet, such as the Mediterranean diet, and regular exercise, according to the American Heart Association (AHA) guidelines. The AHA guidelines recommend at least 150 minutes per week of moderate exercise or 75 minutes per week of vigorous exercise (or a combination of moderate and vigorous activity). Research shows that you can even experience benefits if you divide your time into two or three segments of 10 to 15 minutes per day. You should also see your primary care provider to have your blood pressure, blood glucose, and cholesterol monitored and managed. 

I’ve been on a number of treatments, including chemotherapy and targeted therapies. Should my heart be monitored regularly? How is heart health managed differently in people with MBC?

In the setting of metastatic breast cancer, where treatment is controlling incurable cancer, the balance between the treatment side effects and cancer’s symptoms are carefully weighed. If the treatment is working and there are no symptoms of CHF, the benefits are outweighing the risks!

If treatment includes chemotherapy or other therapies that can hurt the heart, then your doctor will carefully monitor for symptoms of decline in heart function. Your doctor may check the heart or have you see a cardiologist to consider starting medicines that would prevent decline in heart function, so you stay in better shape for longer. There is also a medicine, called dexrazoxane (Zinecard), that can protect the heart and decrease heart toxicity from anthracyclines, so you can continue to take anthracyclines for longer without them causing heart problems.   

My heart was monitored through treatment and found to be healthy. But my oncologist recommended I see a cardiologist and have regular heart monitoring for the rest of my life. Is that common?

It would not be unreasonable for you to meet a cardiologist, but we are still in the process of determining which patients need to see and be monitored by a cardiologist and which patients do not.  

Do cancer doctors understand long-term effects different treatments can have on the heart? I’m wondering if I can find a doctor who specializes in both breast cancer and heart health.

Yes! Your cancer doctor is familiar with the side effects of breast cancer treatments and their effects on the heart. The long-term benefits and risks, based on information learned from large clinical trials, are considered in all treatment recommendations. Also, cancer doctors are increasingly recommending a healthy diet and exercise to improve overall health and well-being. These lifestyle changes most certainly make a difference to heart health and we are gathering data from clinical trials to see if it makes a difference to breast cancer outcomes.  

I had left breast radiation in 2008 after a lumpectomy. I have been treated for atrial fibrillation (AFib) since 2013. Could the radiation have caused me to develop AFib?

 It is very unlikely that radiation caused atrial fibrillation (AFib). In fact, this association has not been reported.

Radiation’s effects on the heart are due to direct effects of the radiation on the heart muscle. Most of the left ventricle, or main pumping chamber of the heart, and some of the most important blood vessels that carry blood to the heart muscle, are located near the left chest wall. When exposed to radiation, the heart muscle and blood vessels can become scarred, leading to weakening of the heart muscle and narrowing of blood vessels. Weakening of the heart muscle can cause the heart not to work as well. Narrowing of blood vessels can cause myocardial ischemia (in which the heart can't get enough oxygen) and, if severe, heart attacks.

So, if you picture radiation from breast cancer, given across the chest wall, you can see how radiation to the left chest wall/breast might include part of the heart. Right breast radiation is unlikely to include meaningful exposure to the heart.

The cause of AFib is not always known. It is very common with increasing age. Neither the atrium nor the conduction system that controls heart rhythm is in the region of the heart most likely to be included in the radiation field, even for a left-sided breast cancer. 

Is there data on how long people live after early-stage breast cancer treatment and what they die from? In particular, how many die from some form of heart failure?

Yes, but this is a very complicated question. The cause of death, such as breast cancer or other causes, depends on the stage and type of breast cancer, the number and type of other coexisting diagnoses, called comorbidities, including heart disease, and many other factors. We do know that the risk of heart failure is related to genetic factors, as well as the effects of certain chemotherapies and radiation therapy. We also know that survival from breast cancer is improving and women are living long enough that we are now seeing heart disease as a more common cause of death than breast cancer, especially in women who have had early-stage breast cancer.

My ejection fraction is down after chemo and radiation. I was told this is normal and can get better. I am on medicine to protect my heart as I finish trastuzumab (Herceptin). When can I expect my heart to get better?

Ejection fraction, or EF, is usually now measured by a test called an echocardiogram. With echocardiograms, the cardiologist studies the heart images and measures the volume of the heart when it fills with blood and then the volume when it pushes the blood out, or contracts. The difference in these two is called the EF, given as a percentage. So, if your heart pumps to half its volume, the EF is 50 percent. Normal EF is 50-55 percent or greater. The exact number can vary with dehydration, slow or fast heart rate, and other things. To make it even more complex, there is probably a margin of error of 10 percent in either direction, so if we get a reported EF of 60 percent, it may be between 50 and 70 percent.

We have learned that the decline of EF with trastuzumab (Herceptin) is generally reversible.
The field of cardio-oncology is growing. A cardiologist with expertise in cardio-oncology will monitor and take care of you as a person who has a known risk factor for heart failure, so find a cardiologist with this particular interest in your area and go see them.

Are there supplements I can take before, during, or after treatment that can help my heart health?

As far as we know, there are not any supplements that help heart health during cancer treatment. We know that some supplements may interfere with cancer treatment though, so please consult your doctor or check out the “About Herbs” online resource from Memorial Sloan Kettering Cancer Center. 

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