Abstract

To the Editor:

Cancer remains the second most common cause of death in the United States while atrial fibrillation (AF) is the most common arrhythmia in elderly people. Though there are several proposed risk factors for AF, it is unclear if cancer is a risk factor for AF or vice-versa. Recent data suggest that AF may be an inflammatory complication resulting from initiation of an inflammatory response to any inciting agent such as stress, surgery, and infection.¹ Chung et al analyzed the association between cancer, AF and inflammatory state and reported that atrial arrhythmias were significantly more common in patients with a history of malignancy ([18.3%] vs [5.6%], P = 0.018).¹A statistically significant elevation of serum levels of C-reactive protein was found in patients with AF and in patients with a history of cancer.²However, cancer was not found to be an independent predictor of atrial arrhythmias in multivariable analysis. Walsh et al reported that AF correlated with worse two-year survival (P = 0.04) in 175 cancer patients. However, in a Cox regression analysis AF was not found to be an independent predictor of survival.³ Cancer progression causing extreme inflammatory stress, surgical treatments especially intrathoracic procedures, chemo- and radiation therapies are all potential inciting factors for AF.⁴ Chemotherapeutic agents such as cytotoxic agents and targeted therapies including monoclonal antibodies that target tyrosine kinase receptors, anti-angiogenic drugs, small molecule tyrosine kinase inhibitors and chemoprevention agents such as cyclooxygenase-2 inhibitors and high-dose corticosteroids affect the cardiovascular system and can contribute to AF.⁵ Additional reasons such as persistent pain, hypoxia, tachycardia, electrolyte abnormalities and malnourishment which are common manifestations in cancer patients can cause several autonomic, metabolic and endocrine abnormalities contributing to AF. Management of AF also remains a challenge in cancer patients due to increased risk of bleeding, unpredictable anticoagulant response and lack of controlled studies in this population. There are no specific American College of Cardiology/American Heart Association/European Society of Cardiology guidelines to date for the management of AF in this unique set of patients. The incidence of AF in cancer patients remains underrecognized. There is a need for more epidemiological studies showing the association between AF and various types of cancers to establish specific cancers at risk for AF and optimize treatment and preventive strategies for favorable patient outcome.