MELBOURNE – The overall prevalence of atrial fibrillation in people who have or have had cancer is 10 times that of individuals without cancer, according to a study presented at the International Society on Thrombosis and Haemostasis congress.
, of the division of hematology and hemostaseology at the Medical University of Vienna reported on a nationwide cohort study using health insurance data from more than 8.3 million people in Austria, including roughly 159,000 with a diagnosis of cancer and 113,000 with a diagnosis of atrial fibrillation.
The analysis found that, in individuals whose records showed a diagnosis of cancer, there was a 950% higher relative risk of also having a diagnosis of atrial fibrillation, compared with those with no cancer diagnosis.
The overall prevalence of atrial fibrillation among individuals with a cancer diagnosis was 9.8%, compared with 1.2% in those without cancer.
There was significant variation in relative risk according to age. Although the prevalence of atrial fibrillation increased with age, the highest relative risks were seen in the youngest age groups.
In those aged 12 years or under with a cancer diagnosis, the relative risk of atrial fibrillation was 150 times greater than in those without cancer, and in those aged 13-18 years, it was 200 times higher. At the other end of the age spectrum, individuals aged 70-79 years with a recorded cancer diagnosis, the relative risk of atrial fibrillation was still 130% higher than the noncancer population, and in those aged 80-90 years it was a significant 54% higher.
However, the analysis did not find any effect of gender on the risk of atrial fibrillation associated with cancer, regardless of the age group.
Researchers also examined the influence of different cancer types. They found the highest relative risk of atrial fibrillation was in persons with hematologic malignancies – at nine times the risk in the noncancer population – and the lowest was in the endocrine cancer patients, who had three times the risk.
Dr. Ay told the conference that the association between cancer and atrial fibrillation had been suggested in the literature, but it was still an unexplored field. “The exact magnitude of this association between cancer and atrial fibrillation is still unclear.”
There was also the question of what mechanisms might underlie the association. Dr. Ay pointed out that the health insurance database did not allow researchers to explore the temporal relationship between the two diagnoses, and therefore could not tell which came first.
One audience member queried whether the fact that cancer patients were likely to be visiting a clinician more frequently might mean that the atrial fibrillation would be more likely to be diagnosed.
To that, Dr. Ay suggested the significantly higher relative risk in children was supportive of the notion that cancer itself, or treatment effects, were influencing atrial fibrillation risk.
“There is evidence suggesting that cancer treatments are triggering atrial fibrillation,” he said in an interview. “Also, patients with cancer have situations of in which they are sick – they have neutropenia or sepsis and so on – which can also trigger atrial fibrillation.”
Given the limitations of the retrospective cohort study, Dr. Ay said he was hoping to do a prospective study that would enable baseline measurements of cancer patients to determine how much of the atrial fibrillation was preexisting.
“We have also more and more cancer survivors, and over the years they’re living longer and the likelihood of getting atrial fibrillation increases,” he added.
Commenting on the data,, chief of hematology at the Memorial Sloan Kettering Cancer Center in New York, said it was very important to quantify the association between cancer and atrial fibrillation.
“What’s striking to me is how many people with cancer come in with preexisting atrial fibrillation,” he said. “It could be that they have cancer and they’re already messed up, but we have, on a given day, several people coming in with newly diagnosed cancers, already on warfarin or apixaban or rivaroxaban because they have atrial fibrillation.”
Dr. Ay reported advisory board positions and speaking engagements for the pharmaceutical sector.