Atrial Fibrillation in a Cancer Setting: Understanding Unmet Needs in Cardio-Oncology Provider Specialty, Anticoagulation, and Stroke Risk in Patients With Atrial Fibrillation and Cancer

A new study by Neal et al. demonstrated that although patients with atrial fibrillation (AF) and cancer were less likely to see a cardiologist or fill anticoagulant prescriptions, cardiology involvement was associated with increased anticoagulant prescription fills and favorable AF-related outcomes. The results of the study were published online in JACC.

Past literature showed that patients with a history of cancer had a >2-fold risk of developing cardiovascular disease (CVD) and were less likely to receive guideline-driven therapy after acute MI compared with those without cancer. These disparities led to a growing interest in understanding existing practices and unmet needs in the field of cardio-oncology. Moreover, cardiotoxicity with resultant AF was a well-established side effect of radiation or chemotherapy, and new-onset AF in otherwise healthy patients was even associated with long-term cancer risk. However, it was still unknown whether early cardiology involvement shortly after atrial fibrillation (AF) diagnosis was associated with favorable outcomes in AF patients who had cancer.  Therefore, the investigators of this study aimed to examine the relationship between early cardiology involvement after AF diagnosis in patients with a history of cancer. The study population was the Truven Health Marketscan database, which was comprised of private insurance claims for several large employers and claims from the Medicare Supplemental database.

Neal et al. examined associations of early cardiology involvement with oral anticoagulation use, stroke, and bleeding among nonvalvular AF patients with a history of cancer. International Classification of Disease-9th Revision-Clinical Modification codes in any position was used to identify cancer diagnosis prior to AF diagnosis.  Specifically, they compared outcomes of cancer patients seen by primary care providers versus cardiologists.  “Early” cardiology involvement and anticoagulation prescription fills were assessed from 3 months prior through 6 months after a new diagnosis of AF. Provider specialty and filled anticoagulant prescriptions 3 months prior to and 6 months after AF diagnosis were obtained. Poisson regression models were used to compute the probability of an oral anticoagulant prescription fill, and Cox regression was used to estimate the risks of stroke and major bleeding.

The investigators found that a total of 17% of AF patients had a history of cancer. Cancer patients seen by cardiology were generally sicker, with higher rates of heart failure, hypertension, prior MI, and peripheral artery disease compared with those seen by primary care. Overall, cardiology involvement was less likely to occur among patients with a history of cancer than those without (relative risk [RR]: 0.92 [95% confidence interval (CI): 0.91 to 0.93]). Patients with a history of cancer were less likely to fill prescriptions for anticoagulants (RR: 0.89 [95% CI: 0.88 to 0.90]) than those without cancer, and similar results were observed across cancer types. On the other hand, patients with cancer were more likely to fill prescriptions for anticoagulants, (RR: 1.48 [95% CI: 1.45 to 1.52]) if seen by a cardiologist. The effects of early cardiology involvement were not limited to anticoagulation use, as cancer patients were also more likely to receive rhythm control therapy (relative risk:1.65; 95% confidence interval: 1.60 to 1.70). However, these patients had higher rates of hospitalizations for AF and heart failure, possibly due to a combination of more aggressive therapy and baseline comorbidities. Additionally, a reduced risk of stroke (hazard ratio: 0.89 [95% CI: 0.81 to 0.99]) was observed among all cancer patients who were seen by a cardiology provider, without an increased risk of bleeding (hazard ratio: 1.04 [95% CI: 0.95 to 1.13]). Similar results were observed when the analysis was stratified by active versus a remote history of cancer. Although the study was not powered to detect differences in provider outcomes among specific cancers, on stratifying malignancies by perceived thrombogenicity, investigators noted that cardiology involvement was consistently associated with a reduction in ischemic stroke in patients with cancers perceived to be more (colon, lung, pancreas, and hematologic) or less (breast and prostate) thrombogenic.

In accompanying editorial, Dr. Sean T. Chen and Chiara Melloni emphasized that the investigators should be commended on an insightful and thought-provoking analysis. According to them, this was one of the first studies identifying the suboptimal use of anticoagulation therapy in this population and the results of the study made a compelling argument that early cardiology involvement was associated with lower rates of stroke without higher bleeding risk, even in those with actively treated cancer. Variations in treatment reflected differing perceptions of thromboembolic and bleeding risk among specialties. However, they spoke of the future of cardio-oncology remarking that “The management of cancer patients must extend beyond their primary malignancy and will require an interdisciplinary approach from oncologists, primary care providers, and other subspecialists. The increase in survivorship is a testament to the dramatic improvements in cancer therapy, but continued emphasis on a patient’s diagnosis of cancer can shift significant attention away from other essential aspects of care. AF has emerged as an important, yet undertreated cardiovascular complication in the setting of malignancy. Future recognition and appropriate management of AF in this setting will be crucial in reducing morbidity and mortality in this vulnerable population.”