Atrial fibrillation (AFib) occurs at a higher rate in patients with cancers than in the general population, and an association between AFib and thoracic surgery has been noted since the 1970s. There is also growing evidence of a link between AFib and multiple types of cancers. However, according to a study published Dec. 18 in the Journal of the American College of Cardiology, there is a lack of evidence for the management of AFib in cancer patients, which enforces an individualized approach needed for the treatment of AFib cancer patients.

The review looked at several previously published studies, including a study on 24,125 cancer patients which found a post-operative AFib rate of 4.2 percent versus 2 percent in the general population. In addition, new onset AFib in cancer surgery patients carries a hazard ratio of 1.98 for thromboembolism and 6.3 for heart failure. Another large population study found that patients with AFib were nearly 12 times as likely to have colorectal cancer than matched patients who did not have AFib. AFib occurring during lung cancer surgery increased post-operative mortality and five-year mortality, length of stay and ICU admissions.

The authors note that the physiologic basis for the association between AFib and cancer is not clear. AFib could be a comorbid condition because AFib and cancer share predisposing factors such as age, electrolyte abnormalities, hypoxia and metabolic disorders. Autonomic nervous system imbalances may predispose patients to AFib, and tumors in cardiac or adjacent tissues may play a direct role in AFib. Multiple studies suggest that AFib may be an inflammatory complication of cancer and some types of cancers, particularly cranial tumors and hematologic malignancies, increase the risk of hemorrhage.

The review also noted that multiple oncology agents may induce AFib, including most cytotoxics (cisplatin, 5-fluorouracil, doxorubicin, paclitaxel/docetaxel, ifosfamide, gemcitabine and mitoxantrone), high-dose corticosteroids, antiemetics, targeted therapies and bisphosphonates. Further, cancer is a prothrombotic state that has not been incorporated into thromboembolic event risk predictors such as CHADS2 or CHA2DS2-VASc. Some anti-cancer agents, particularly angiogenesis inhibitors, have been implicated in thromboembolic complications, and response to coagulation may be unpredictable due to the effects of medications or metabolic abnormalities associated with cancer.

"The clinical features of cancer patients render individually tailored therapy crucial, especially in antithrombotic prophylaxis," wrote the study's lead author, Dimitrios Farmakis, MD, University of Athens Medical School, Athens, Greece. "Features like intracranial tumors, chemotherapy-induced thrombocytopenia or coagulation defects may predispose to bleeding and may constitute contraindication to antithrombotic therapy even in patients with high thromboembolic risk. On the other hand, certain malignant tumors and several chemotherapeutic agents are associated with increased thromboembolic risk and thromboembolic prophylaxis may be needed even in patients classified as low-risk."

Moving forward, the authors note that "there are several issues that need to be addressed by future research concerning epidemiology, pathogenesis, diagnosis, prevention and treatment."

Keywords: Neoplasms, Angiogenesis Inhibitors, Taxoids, Autonomic Nervous System, Thromboembolism, Deoxycytidine, Heart Failure, Hematologic Neoplasms, Diphosphonates, Colorectal Neoplasms, Lung Neoplasms, Thrombocytopenia, United States, Hemorrhage