Assessing Patients Undergoing Cancer Treatment

By Balaji Tamarappoo, MD, PhD

New chemotherapy agents have improved cancer survival, yet some may cause lasting damage to the heart. This is particularly concerning for patients who are at risk for or have existing heart disease. Although cardiotoxicity does not affect all patients, detecting problems early on provides the opportunity for proactive treatment. The goal is to help patients complete their cancer treatment without incurring damage to the heart.

Prior to starting chemotherapy, we advise obtaining an echocardiogram to determine baseline heart function. This will serve as a point of reference for any changes that may occur during or following completion of therapy.

Anthracyclines in general, and doxorubicin in particular, are among the most common chemotherapeutic agents known to be cardiotoxic. Cumulative doses of 400-500 mg per meter2 of body surface area can cause heart failure or cardiomyopathy at any time up to several years after treatment ends.

When a patient has received around 250 mg per meter2 of body surface area, we begin to become concerned about toxicity. We obtain a second echocardiogram at this point and compare it to the baseline echo. If all is well, the patient may continue treatment. If any abnormalities of heart function are seen, we may be able to add beta-blockers and ACE inhibitors to prevent further damage during treatment. This also provides an opportunity for the oncologist to consider alternative chemotherapy.

After treatment has been completed, we look again. If no disturbing changes have taken place, we have the patient return at one year. From this point on, a repeat echo is only necessary if the patient experiences symptoms of a heart problem.

Trastuzumab is an agent known to cause heart failure and arrhythmias during treatment. Although these side effects are reversible, and long-term effects are rare, they need to be addressed. The drug is usually given for one year, so echocardiograms at baseline, 6 months and end of treatment are advised. Treatment with tyrokinase inhibitors may cause hypertension that needs appropriate treatment.

Patients taking beta-blockers or ACE inhibitors may find that their oncologist discontinues these medications if they experience side effects from chemotherapy. It is wise to follow these patients closely to ensure the medications are restarted after the cancer has been addressed.

While chemotherapy agents can affect the heart muscle, radiation therapy tends to primarily affect the valves. Pre- and post-radiation echos are reasonable to evaluate valve function. If calcifications are seen, the patient should be followed every couple of years to monitor the development of valve disease.

Because heart damage can develop within the first year after therapy, and even several years after therapy, it is important for cancer patients to be followed by a cardiologist or cardio-oncologist, who can be alert for the development of symptoms including weakness, fatigue, swelling of the legs and feet, chest pain, arrhythmias or dizziness and provide immediate evaluation and early treatment, if needed.

A cardio-oncologist is also warranted when a patient with a prior history of cancer develops new cardiac problems or heart failure requiring advanced treatment.

Although echocardiography provides a cost-effective method of monitoring these patients, the addition of strain imaging provides a superior method of visualizing myocardial deformation. In the Cardio-Oncology Center at Cleveland Clinic, we are focusing our research on the value of strain imaging. Currently, we are assessing whether abnormal strain measurements on a clinically stable patient signify a bad prognosis later in life.