Many medications treat diseases and improve health. However, some drugs can have unintended side effects, specifically affecting the heart. These are known as cardiotoxic medications, meaning they can damage the heart’s structure or interfere with its normal function. Awareness of these potential effects helps patients and caregivers understand the need for careful monitoring during treatment. Understanding which medications pose this risk and how they affect the heart is important for patient safety.
Medications That Can Harm the Heart
Certain cancer treatments, particularly chemotherapy, are known to have cardiotoxic effects. Anthracyclines, such as doxorubicin and daunorubicin, are examples that can damage heart muscle. Some targeted therapies, like trastuzumab, also risk heart dysfunction. Platinum compounds, such as cisplatin, and antimetabolites like 5-fluorouracil, are linked to cardiovascular issues including thrombosis and myocardial infarction.
Psychiatric medications can also affect heart health, with some antipsychotics and tricyclic antidepressants causing cardiac issues. Clozapine and ziprasidone, for instance, have been associated with heart rhythm problems and myocarditis or cardiomyopathy. Tricyclic antidepressants also contribute to heart rate changes and electrical abnormalities.
Anti-inflammatory drugs, non-steroidal anti-inflammatory drugs (NSAIDs), can increase cardiovascular risk. Long-term use or high doses of NSAIDs, including ibuprofen and diclofenac, can elevate blood pressure, cause fluid retention, and exacerbate heart failure. This risk is relevant for individuals with pre-existing heart conditions.
Some diabetes medications can increase heart failure risk. Older drugs like thiazolidinediones (e.g., pioglitazone, rosiglitazone) can cause fluid retention and weight gain, placing extra strain on the heart. Certain dipeptidyl peptidase-4 (DPP-4) inhibitors, such as saxagliptin and alogliptin, are also linked to increased hospitalization for heart failure.
Paradoxically, some medications used to treat irregular heartbeats, known as antiarrhythmics, can cause new or worsened rhythm problems. Drugs like amiodarone and flecainide, while used to stabilize heart rhythms, can affect the heart muscle over time, leading to bradycardia or arrhythmias. Digoxin, another antiarrhythmic, can also cause proarrhythmic effects, especially with increased intracellular calcium.
How These Medications Affect the Heart
Cardiotoxic medications can affect the heart in several ways, often by damaging its structures or disrupting its functions. One common way is through damage to the heart muscle, leading to a condition called cardiomyopathy. Certain drugs can weaken or thin the heart muscle, making it less effective at pumping blood throughout the body. This can lead to reduced left ventricular ejection fraction, a measure of how well the heart pumps blood.
Another mechanism involves disturbances to the heart’s electrical system, resulting in arrhythmias. Some medications interfere with the electrical signals that regulate heartbeats, causing them to be too fast (tachycardia), too slow (bradycardia), or irregular. This can manifest as prolongation of the QT interval on an electrocardiogram, which can increase the risk of serious rhythm disturbances.
Some drugs can affect the blood vessels that supply the heart, causing narrowing or spasms of the coronary arteries. This reduction in blood flow to the heart muscle can lead to conditions like myocardial ischemia or even heart attacks. For example, some chemotherapy agents can induce cardiac ischemia.
Fluid retention is another way medications can strain the heart. Certain drugs cause the body to hold onto excess fluid, increasing the volume of blood the heart needs to pump. This added workload can put significant stress on the heart, potentially leading to or worsening heart failure.
Some medications can trigger inflammation of the heart muscle (myocarditis) or the surrounding tissues (pericarditis). This inflammation can impair the heart’s function, contributing to cardiac dysfunction. Certain chemotherapy agents, for example, have been associated with inflammatory lesions.
Signs of Heart Damage and Monitoring
Recognizing signs of heart damage from medications is important for timely intervention. Common symptoms include shortness of breath, particularly with exertion or when lying flat, and swelling in the legs, ankles, or feet. Patients might also experience unusual fatigue, chest pain, dizziness, or heart palpitations (a feeling of racing or skipping beats). Unexplained weight gain can also be a sign of fluid retention, which burdens the heart.
These symptoms can be subtle and might be mistaken for other conditions or side effects of the underlying illness being treated. Patients should communicate any new or worsening symptoms to their doctor immediately, even if they seem minor. Early reporting can lead to earlier detection and management of cardiotoxicity.
Medical professionals use diagnostic tests to monitor for heart damage. An echocardiogram, often referred to as an “echo,” is an ultrasound of the heart that provides images of its structure and assesses its pumping function, including the left ventricular ejection fraction. An electrocardiogram (ECG or EKG) measures the heart’s electrical activity and rhythm, helping to identify any irregularities or conduction abnormalities.
Blood tests detect biomarkers that indicate heart stress or damage. Cardiac troponins (cTnI and cTnT) are markers released when heart muscle cells are injured. Natriuretic peptides (BNP or NT-proBNP) are elevated when the heart is under stress or experiencing fluid overload. Regular clinical assessments, including blood pressure monitoring and symptom reviews, are also part of ongoing care to catch changes early.
Reducing Risks and Managing Cardiotoxicity
Several factors increase susceptibility to cardiotoxicity. Individuals with pre-existing heart conditions, such as coronary artery disease or a history of heart failure, face higher risk. Older age, high blood pressure, diabetes, and kidney disease also predispose patients to cardiac side effects. The cumulative dose of certain cardiotoxic drugs, particularly anthracyclines, also influences heart damage risk.
Preventative strategies are often employed to minimize the risk of cardiotoxicity. Doctors carefully adjust medication doses and may administer certain drugs slowly to reduce the immediate impact on the heart. Cardioprotective medications may be prescribed alongside cardiotoxic treatments to shield the heart. For instance, angiotensin-converting enzyme (ACE) inhibitors, beta-blockers, and statins can help reduce heart failure in patients undergoing certain chemotherapy regimens. Dexrazoxane is specifically used to reduce anthracycline-induced cardiotoxicity.
Regular monitoring is an important part of prevention, allowing for early detection of any changes in heart function. Lifestyle modifications also help maintain heart health. Adopting a heart-healthy diet, regular physical activity, avoiding smoking, and limiting excessive alcohol consumption can help reduce overall cardiovascular strain.
If cardiotoxicity is established, management focuses on mitigating damage and treating any resulting heart conditions. The prescribing doctor may adjust the dose of the cardiotoxic medication or, if medically appropriate, discontinue it to prevent further harm. If cardiotoxicity leads to heart failure, standard treatments for this condition are initiated. These often include diuretics to reduce fluid retention, and specific heart medications like ACE inhibitors, angiotensin receptor blockers (ARBs), and beta-blockers to improve heart function and manage symptoms. In some cases, patients may be referred to a cardiologist for specialized care and consideration of cardiac rehabilitation programs to help restore heart function and improve quality of life.