Current glucocorticoid users are almost twice as likely to develop atrial fibrillation or flutter as people who have never used the drugs, results of a case–control study suggest.
As reported in the Archives of Internal Medicine, Christian Fynbo Christiansen (Aarhus University Hospital, Denmark) and colleagues found that 6.4% of 20,221 patients with a first diagnosis of atrial fibrillation or flutter were current users of glucocorticoids, with a prescription filled within 60 days of the index date, compared with 2.6% of 202,130 age- and gender-matched control individuals.
Logistic regression analysis showed that current glucocorticoid users therefore had a significant 1.92-fold increased odds of atrial fibrillation or flutter compared with never users, after adjusting for age group, gender, comorbidity, and drug use.
New glucocorticoid users, whose first prescription was filled within 60 days of the index date, had a greater increase in odds of atrial fibrillation or flutter than long-term current users whose first prescription was filled earlier, at respective adjusted odds ratios (ORs) of 3.62 and 1.66 relative to never users.
Former glucocorticoid use (last prescription filled more than 60 days before index date) was not associated with atrial fibrillation or flutter, being found in 11.7% and 9.9% of patients and controls, respectively, and associated with an OR of 1.00 versus never use.
Glucocorticoids are widely used to treat inflammatory and autoimmune diseases. Subgroup analyses confirmed the findings held true for patients with and without chronic obstructive pulmonary disease, or asthma and cardiovascular diseases. The increased odds of arrhythmias were also evident but the associations “statistically imprecise” among patients with connective tissue disease and rheumatoid arthritis, the researchers say.
Christiansen and colleagues note that the results build on data from two previous case–control studies that found a link between glucocorticoid use and atrial fibrillation.
The mechanism linking glucocorticoid use and atrial fibrillation or flutter remains unclear, but the researchers write: “Our finding of the highest risk among new users… indicates either a short-term adverse effect (eg, development of hypertension within a few days after the commencement of glucocorticoid treatment) or an effect associated with the severity of the underlying disease (eg, inflammation).
“Glucocorticoids may also increase plasma volume and induce hypokalemia by mineralocorticoid-like action, and it has been suggested that even a subclinical fluctuation in serum potassium level from a local cellular potassium efflux owing to a direct effect on the cell membrane may induce arrhythmias.”
My guess is that those with autoimmune diseases would suffer even worse consequences if they DIDN'T have glucocorticoids available to them.