Increased risk of Atrial Fibrillation in Certain Ankylosing Spondylitis Patients

Ankylosing spondylitis (AS) patients younger than 40 and those treated with tumor necrosis factor inhibitors (TNFi) are at a higher risk of developing atrial fibrillation, a heart condition that causes an irregular and often abnormally fast heart rate, a population study shows.

These results support the need for early screening for atrial fibrillation and stroke prevention among these high-risk patients.

The study, “Ankylosing spondylitis: A novel risk factor for atrial fibrillation — A nationwide population-based study,” was published in the journal International Journal of Cardiology.

It is well-documented that AS increases the risk of cardiovascular diseases, namely aortitis (inflammation of the aorta), valvular disease, and conduction abnormalities such as atrioventricular block — where blood conduction between different areas of the heart is impaired.

Atrial fibrillation, the most common cardiac arrythmia, is frequently associated with inflammatory conditions, including AS.

Researchers here investigated the risk of atrial fibrillation in AS patients in South Korea, taking into consideration other cardiovascular risk factors and accounting for the severity of AS based on medication.

The study analyzed 14,129 patients newly diagnosed with AS recruited from the Korean National Health Insurance Service database between 2010 and 2014. A control group of 70,645 non-AS individuals was used for comparison. Individuals were followed for 3.5 years for new-onset atrial fibrillation. The mean age of subjects was 41.8 years, and males made up 71.5% in both groups.

After the follow-up period, new-onset atrial fibrillation was diagnosed in 114 patients (2.3%) of the AS group and 372 patients (1.5%) of the non-AS group. AS patients showed a higher incidence of atrial fibrillation than the non-AS group, with a 28% increased risk of atrial fibrillation development.

Most (95%) patients were treated with non-steroidal anti-inflammatory drugs (NSAIDs), including methotrexate (sold under the brand names Trexall and Rheumatrex, among others) prescribed to 2,635 (18.7%) patients, and sulfasalazine (brand name Azulfidine, among others) in 8,699 (61.6%) patients.

A total of 3,899 AS patients (27.6%) were on TNFi therapies. These patients were younger, included more men, and had lower cardiovascular risk factors than the AS group without TNFi therapy. In addition, the TNFi therapy group used more NSAIDs, methotrexate (33.6%), and sulfasalazine (79.8%) than the group not on TNFi therapy.

Patients receiving TNFi had a 60% increased risk of atrial fibrillation compared with the control group. Patients who did not receive this type of therapy had a statistically insignificant risk of developing the condition.

Importantly, AS patients receiving TNFi who were also either on methotrexate or sulfasalazine did not show an increased risk of atrial fibrillation compared with those not on TNFi.

Because “patients who were prescribed TNFi would have more severe symptoms that could not be controlled by NSAIDs and conventional disease-modifying anti-rheumatic drugs,” researchers believe that these results “mean that the greater the inflammation, the greater the incidence of AF and this strongly supports the view that inflammation is associated with AF.”

When classifying patients according to age, those from 20 to 39 years old had a threefold increase in atrial fibrillation compared with individuals of the same age in the control group. In the older age group (those over 40), the absolute incidence of atrial fibrillation increased, but the impact of AS on its development was not as strong as in the younger age group. According to the researchers, this “emphasizes the need for early AF [atrial fibrillation] screening,”

AS patients with cardiovascular risk factors also had higher absolute incidence rates of atrial fibrillation risk. However, ankylosing spondylitis only enhanced the risk of atrial fibrillation in patients without such risk factors.

These results highlight “the need for early [atrial fibrillation] screening” in high-risk AS patients, which can have an important impact in the quality of their clinical follow-up,” the researchers wrote.

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