What Is Cardiotoxicity?
Cardiotoxicity refers to the damage to the muscles and valves of the heart that arises as a complication of cancer treatments. People who receive cancer treatments like chemotherapy, targeted therapy, and radiation therapy are more prone to develop cardiotoxicity. It can develop several years after receiving cancer treatments, especially in adults who received specific cancer treatments during childhood. It can cause severe damage to the heart and makes it difficult to pump blood throughout the body. It is potentially a life-threatening condition that needs early diagnosis and proper treatments to be cured. Periodic assessments of cancer patients for cardiotoxicity are useful in diagnosing the condition at a much earlier stage and preventing its fatal complications.
What Are the Causes of Cardiotoxicity?
Cardiotoxicity is most commonly caused by specific cancer treatments such as;
Chemotherapy: Chemotherapy-induced cardiotoxicity is a major factor responsible for increased mortality and morbidity in cancer survivors. Chemotherapy induces severe damage to heart muscles and valves, leading to abnormal heart rhythms, high blood pressure, and heart failure. The different chemotherapeutic agents that cause cardiotoxicity include;
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Anthracyclines: Anthracycline is a class of chemotherapy drugs used to treat several cancers, such as leukemia, breast cancer, sarcoma, lymphoma, and multiple myeloma. Anthracycline-induced cardiotoxicity is mostly caused by an anthracycline drug called Doxorubicin. Doxorubicin induces cardiotoxicity by generating free radicals in the body, which ultimately leads to heart dysfunction and heart failure.
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Alkylating Agents: Alkylating agents are anticancer drugs used in the treatment of lung cancer, breast cancer, and different types of blood cancer. The alkylating agents that induce cardiotoxicity include Cyclophosphamide, Cisplatin, Mitomycin, and Carmustine.
Targeted Drug Therapy: Targeted drug therapy is a type of chemotherapy used to treat several cancers. Examples of targeted therapy drugs that cause cardiotoxicity include Trastuzumab, Lapatinib, and Sorafenib. These drugs induce reversible myocyte dysfunction and damage to the heart muscle.
Radiation Therapy: People who receive radiation therapy for breast and lung cancer are more prone to developing cardiotoxicity. This is because high doses of radiation therapy can cause severe damage to different components of the heart, including heart valves, capillaries, coronary arteries, heart muscles, and conducting system.
Some of the other risk factors that induce cardiotoxicity include;
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Anorexia nervosa which is a type of eating disorder characterized by an intense fear of weight gain, distorted perception of weight, and abnormally low body weight.
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Long-term abuse or heavy ingestion of stimulants such as Cocaine.
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Heavy metal poisoning.
What Are the Different Heart Problems That Cardiotoxicity Causes??
Cardiotoxicity may cause different heart problems, such as;
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Cardiomyopathy: Cardiomyopathy is a cardiac muscle disease that makes the heart difficult to pump blood to different body parts and ultimately leads to heart failure.
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Myocardial Infarction: A heart attack, medically termed myocardial infarction, is an emergency medical condition that occurs due to a lack of blood supply to the heart muscle.
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Arrhythmia: Arrhythmia refers to an irregular heartbeat. People with arrhythmia may have a faster or slower heartbeat.
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Heart Valve Disease: Heart valve disease occurs due to damage to the different valves of the heart. Valvular stenosis, valvular atresia, and valvular insufficiency are different heart valve diseases caused by cardiotoxicity.
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Congestive Heart Failure: Congestive heart failure is a chronic condition that occurs when the heart loses its ability to pump blood, leading to severe complications.
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Hypertension: Hypertension is a systemic condition in which blood pressure is higher than usual.
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Pericardial Effusion: Fluid buildup in and around the heart.
What Are the Symptoms of Cardiotoxicity?
The symptoms may vary with heart problems related to cardiotoxicity. The most common symptoms of cardiotoxicity include;
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Chest pain.
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Shortness of breath.
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Heart palpitations.
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Abdominal enlargement.
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Dizziness.
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Fluid retention in the legs.
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Low or high blood pressure.
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Fatigue.
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Weight gain.
How Is Cardiotoxicity Diagnosed?
Healthcare providers use several tests and measures to diagnose cardiotoxicity by measuring the heart’s pumping and valve function. The different tests include;
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Left Ventricular Ejection Fraction: Left ventricular ejection fraction (LEVF) is a heart test that measures the amount of oxygenated blood pumped by the left ventricle with each contraction. The normal ejection fraction range is about 50 to 75 percent, whereas less than 40 percent indicates severe heart conditions like heart failure and cardiomyopathy.
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Cardiac Stress Test: A cardiac stress test is a heart test that measures the heart’s ability to respond to intense activity in a controlled clinical environment. For example, in this test, the patient may be asked to ride a stationary bike or walk on a treadmill while connected to a machine that measures blood pressure and heart rate.
The healthcare providers recommend specific imaging tests to diagnose cardiotoxicity. It includes;
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Multigated Acquisition Scan (MUGA): MUGA scan is a cardiological test that evaluates the function of the heart’s ventricles. First, the healthcare provider injects a small amount of radioactive chemical called technetium-99m-pertechnetate (Tc-99m) into a vein. The radioactive material then binds to the red blood cells. Next, the healthcare provider uses a special camera to image the movement of radioactive tracers throughout the body as the heart beats.
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Cardiac CT (Computed Tomography) Scan: A cardiac CT scan provides cross-sectional images of the heart. It is most useful in diagnosing cardiotoxicity in people who have received radiation therapy to the chest as a part of cancer treatment.
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Cardiac MRI (Magnetic Resonance Imaging): Some healthcare providers consider cardiac MRI as a gold standard in detecting cardiotoxicity. It uses a magnetic field and radio waves to produce detailed images of the heart's internal structures. It also helps evaluate how blood flows through the heart.
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Echocardiogram: An echocardiogram is the most commonly used imaging tool in diagnosing cardiotoxicity. It uses ultrasound waves and electrodes to check the heart rhythm and view the blood flow through the heart.
How Is Cardiotoxicity Treated?
Healthcare providers may prescribe certain medications to help the heart work more efficiently. The medications include;
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Beta-Blockers: Beta-blockers are medications that help lower the stress on the heart and blood vessels. It helps strengthen the heart muscle, slows the patient's heart rate, reduces blood pressure, treats arrhythmias and hypertension, and prevents heart failure. The beta blockers used in the treatment of cardiotoxicity include Metoprolol and Atenolol.
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ACE Inhibitors: Angiotensin-converting enzyme inhibitors are a class of drugs that helps blood vessels dilate and open. It helps treat heart failure and hypertension by improving the blood flow to the heart and reducing blood pressure. The common ACE inhibitors used in the treatment of cardiotoxicity include Lisinopril and Fosinopril sodium.
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Diuretics: Diuretics treat cardiotoxicity by restoring and maintaining the normal volume of blood in the body. An example of diuretics used in cardiotoxicity is Furosemide.
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Vasodilators: Vasodilators are a group of drugs that dilate blood vessels and allow blood to flow more easily. An example of vasodilators used in the treatment of cardiotoxicity is Isosorbide dinitrate.
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Digoxin: Digoxin helps treat heart failure and arrhythmias associated with cardiotoxicity.
Conclusion
There are no specific measures to prevent cardiotoxicity. However, patients who receive cancer should discuss their risk of developing cardiotoxicity with healthcare providers. Cardiotoxicity that occurs after using Trastuzumab drug is reversible, and it can be treated well with medications like angiotensin-converting enzyme (ACE) inhibitors, diuretics, vasodilators, etc. However, anthracycline-induced cardiotoxicity is often not reversible and requires long-term treatment.
