High-dose corticosteroid therapy may be associated with an increased risk for atrial fibrillation, according to an article in the May 8 issue of Archives of Internal Medicine. Corticosteroids had previously been linked to atrial fibrillation in case reports, the authors wrote.

Cornelis S. van der Hooft, MD, Erasmus University Medical Center, Rotterdam, the Netherlands, and colleagues evaluated 7,983 adults who were age 55 years or older in 1990. The researchers followed the participants through January 1, 2000, or until they developed atrial fibrillation or died. Participants underwent regular medical examinations throughout the study and their prescription information was gathered from pharmacies.

Between July 1, 1991, and the end of the study, 435 cases of atrial fibrillation developed, 385 of which met the researchers’ qualifications for analysis. Among those who had received a prescription for high-dose corticosteroids within one month of the beginning of the study, the risk of atrial fibrillation was six times as high as it was among those who had never taken the medication.

The patients’ underlying conditions did not affect their risk for atrial fibrillation; those who were prescribed high-dose corticosteroids for asthma or chronic obstructive pulmonary disease had the same increased risk of developing atrial fibrillation as those patients who took the medication to treat arthritis, allergies or blood cancers.

Corticosteroids could affect heart function through several different mechanisms, the authors wrote. The medication may affect the balance of potassium in heart muscle cells, which in turn causes the muscle to contract irregularly.

Corticosteroids also may cause retention of sodium and fluid, which can lead to high blood pressure, congestive heart failure or enlarged atria, all risk factors for atrial fibrillation.

“Our findings suggest that patients receiving high-dose corticosteroid therapy are at increased risk of developing atrial fibrillation,” the authors concluded. “Therefore, careful monitoring of these patients by clinical examination and by performing an electrocardiogram before and after high-dose (pulse) therapy could increase the chance to diagnose and treat this serious arrhythmia as early as possible. Because persons who develop atrial fibrillation are at increased risk of serious cardiovascular complications such as heart failure and ischemic stroke and have a chance to develop chronic atrial fibrillation, early detection of atrial fibrillation is essential.”