CHICAGO -- April 28, 2008 -- Alendronate may be associated with an increased risk of atrial fibrillation, according to a report in the April 28 issue of Archives of Internal Medicine. This unexpected adverse effect of the drug may be a class effect, as other recent studies have reported atrial fibrillation with other bisphosphonates.
Susan R. Heckbert, MD, PhD, Professor of Epidemiology, University of Washington School of Public Health and Community Medicine, Seattle, Washington, and colleagues studied women (n = 719) with confirmed atrial fibrillation that began between 2001 and 2004 and control women (n = 966) who were the same age but did not have atrial fibrillation.
More patients with atrial fibrillation (n = 47; 6.5%) compared with control patients (n = 40; 4.1%) had ever used alendronate. After adjusting for other risk factors, having taken alendronate was associated with a higher risk of atrial fibrillation compared with never having taken any bisphosphonate. The researchers estimated that approximately 3% of new atrial fibrillation cases in this population may be attributed to alendronate use.
Bisphosphonates may disrupt the function of regulatory proteins, trigger inflammation, and cause small decreases in blood calcium and phosphate levels, any of which could affect the atria and therefore alter the heartbeat, the authors note. "More information is needed about whether bisphosphonates could have effects on atrial tissue in the long term through these or other mechanisms that favour the initiation or persistence of atrial fibrillation," they write.
"In conclusion," the authors continue, "all drugs have benefits and adverse effects. When new information becomes available about a previously unrecognised benefit or adverse effect, physicians and patients must reweigh the current knowledge about benefits and risks in making treatment decisions for each patient. The benefits of fracture prevention in patients at high risk for fracture will generally outweigh the possible risks of atrial fibrillation. However, it is important to carefully weigh the benefits against the possible risk of atrial fibrillation in women who have only modestly increased fracture risk and those who have risk factors for atrial fibrillation, such as diabetes mellitus, coronary disease, or heart failure."
In an accompanying editorial, Jane A. Cauley, DrPH, Professor, Department of Epidemiology, University of Pittsburgh, Pittsburgh, Pennsylvania, and Kristine E. Ensrud, MD, MPH, Professor of Medicine, University of Minnesota Medical School, Minneapolis, Minnesota, echoed the risk-benefit argument, writing that when physicians are deciding whether to treat a patient with a medication, they must consider "the risks associated with no treatment and the benefits, risks, and adverse effects of each therapy."
Clearly communicating the risks and benefits to the patient is also crucial. "It is often overwhelming for patients to fully understand the overall risks and benefits associated with different therapies," they write. "Some researchers have suggested that a more quantitative presentation of risks and benefits in terms of absolute risk reduction, relative risk reduction, or the numbers needed to treat will improve patient understanding and facilitate shared decisions.
"Future research should evaluate the effectiveness of such strategies in presenting risks and benefits of therapies on patient understanding, compliance, and risk of health outcomes," they conclude.
SOURCE: Archives of Internal Medicine, April 28
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