Heart arrhythmia refers to an abnormal heartbeat, which can be of various types – bradycardia, tachycardia, or fibrillation. These arrhythmias can be caused by several factors, including heart disease, stress, and some medications.

Another potential factor that might cause heart arrhythmia is cancer.

Several studies have looked into the association between cancer and heart arrhythmias.

While the evidence for a clear link is still not conclusive, there are some indications that cancer and its treatments may increase the risk of heart arrhythmias in certain patients. Here are some of the findings and possible explanations.

1. Cancer Treatment and Heart Arrhythmia

Chemotherapy and radiation therapy, which are widely used in cancer treatment, can cause heart toxicity, leading to heart arrhythmias.

For instance, anthracyclines, a class of chemotherapeutic drugs, can damage heart cells and cause cardiomyopathy, which can manifest as an irregular heartbeat. According to a study published in the Journal of the American College of Cardiology, anthracyclines appear to have a dose-dependent association with arrhythmias, meaning that higher doses are more likely to cause arrhythmias than lower doses.

Another study published in the journal Cardio-Oncology found that survivors of breast cancer who received anthracyclines, trastuzumab, or both, had a higher incidence of atrial fibrillation and non-sustained ventricular tachycardia than those who received other treatments or no treatment.

Radiation therapy for cancer of the chest region can also damage the heart and increase the risk of arrhythmias. For example, radiation-induced fibrosis can cause scarring and stiffness of the heart tissue, leading to arrhythmias.

A study published in Circulation: Arrhythmia and Electrophysiology found that radiation therapy was associated with an increased risk of atrial fibrillation and flutter, as well as supraventricular and ventricular arrhythmias.

2. Cancer and Paraneoplastic Syndromes

Paraneoplastic syndromes are a group of rare disorders that can occur in some cancer patients, in which cancer cells produce hormones or other substances that affect the normal functioning of organs and tissues.

Some paraneoplastic syndromes can cause heart arrhythmias or other cardiovascular complications. For example, a rare syndrome called paraneoplastic autonomic neuropathy (PAN) can cause damage to the autonomic nervous system, which controls heart rate and blood pressure.

As a result, patients with PAN may experience tachycardia, bradycardia, or other arrhythmias, as well as orthostatic hypotension (a sudden drop in blood pressure upon standing up).

Another paraneoplastic syndrome that can affect the heart is carcinoid syndrome, which is caused by a type of neuroendocrine tumor called carcinoid tumor.

Carcinoid tumors produce serotonin and other vasoactive substances that can cause diarrhea, flushing, and heart valve damage. In some cases, carcinoid syndrome can cause right-sided heart failure, which can lead to arrhythmias such as ventricular tachycardia or fibrillation.

3. Shared Risk Factors for Cancer and Arrhythmias

Some risk factors for cancer and heart arrhythmias overlap, which may partly explain why some cancer patients are more prone to heart arrhythmias than others.

For example, older age, hypertension, diabetes, and obesity are known risk factors for both cancer and cardiovascular diseases. In addition, certain genetic mutations or variants may predispose individuals to both cancer and arrhythmias.

For instance, mutations in the BRCA1 and BRCA2 genes, which are known to increase the risk of breast and ovarian cancer, have also been associated with an increased risk of atrial fibrillation, according to a study published in the European Heart Journal. Another genetic variant called JAK2 V617F, which is commonly found in patients with myeloproliferative neoplasms (MPN), has also been linked to an increased risk of atrial fibrillation and other arrhythmias, as well as thrombotic events.

4. How to Monitor and Manage Heart Arrhythmias in Cancer Patients

Given the complex interplay between cancer and heart arrhythmias, it is important for cancer patients and their healthcare providers to be aware of the potential risks and to monitor for any signs of heart problems.

Patients who receive anthracyclines or radiation therapy to the chest area should have regular cardiac evaluations, including electrocardiograms (ECGs) and echocardiograms, to detect any changes in heart function or rhythm.

If a cancer patient develops heart arrhythmias, the treatment will depend on the severity and type of arrhythmia, as well as the patient’s overall health and cancer status.

In some cases, arrhythmias can be managed with medications, such as beta blockers or calcium channel blockers, which can slow down the heart rate and reduce the risk of more severe arrhythmias. In other cases, more aggressive treatments may be necessary, such as implantable cardioverter-defibrillators (ICDs) or ablation therapy.

5. Conclusion

While the evidence supporting a direct link between cancer and heart arrhythmias is not yet definitive, there are several potential mechanisms by which cancer and cancer treatments can contribute to arrhythmias, either through direct cardiac toxicity or paraneoplastic syndromes. Healthcare providers who treat cancer patients should be aware of these risks and monitor for any signs of heart problems.

Likewise, cancer patients should be proactive in informing their healthcare providers of any changes in their heart rhythm or other symptoms that may indicate heart problems.