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May 5 - Irregular Heartbeat Affects Women Taking Osteoporosis Drug

Chronically irregular heartbeat (atrial fibrillation) affected women who had taken the bisphosphonate drug Fosamax (alendronate) to combat the bone-thinning disease osteoporosis nearly twice as often as women who had never used it according to new research.

The investigation was the work of researchers from Group Health and the University of Washington, both in Seattle, and colleagues from other research centers in Seattle and San Francisco. It was recently published in the Archives of Internal Medicine. Generic versions of alendronate were approved by the FDA for the treatment of osteoporosis.

Susan Heckbert, MD, PhD, MPH, study leader and a professor of epidemiology and researcher at the Cardiovascular Health Research Unit at the University of Washington, said in a prepared statement that "we studied more than 700 female Group Health patients whose atrial fibrillation was first detected during a three-year period."

Heckbert and colleagues matched the women, who were diagnosed with atrial fibrillation between October 2001 and December 2004, to more than 900 randomly selected female controls who did not have the condition. The controls were also from Group Health and matched the intervention group on age and presence or absence of high blood pressure. They researchers found the following:

* More women with atrial fibrillation than controls had ever used alendronate (47 vs. 40 women).

* Women who had ever taken alendronate had an 86% higher risk of having atrial fibrillation compared with women who had never taken it or any other bisphosphonate drug.

* This figure was obtained after adjusting for the matching variables, a diagnosis of osteoporosis, and a history of cardiovascular disease.

The researchers wrote that "based on the population-attributable fraction, we estimated that 3 per cent of incident AF [atrial fibrillation] in this population might be explained by alendronate use." They concluded that "even use of alendronate was associated with an increased risk of incident AF in clinical practice."

Heckbert says osteoporosis affects mostly older women and impairs their quality of life by setting the stage for fractures. "Careful judgment is required to weigh the risks and benefits of any medication for any individual patient," she explains. "For most women at high risk of fracture, alendronate's benefit of reducing fractures will outweigh the risk of atrial fibrillation."

But she says women who are at high risk of fractures and are also at risk of atrial fibrillation--for instance if they have heart failure, diabetes, or heart disease--may want to talk to their doctor about alternative treatments. Estrogen is an alternative treatment for fracture risk, but other studies on hormone therapy have linked this drug to other heart risks.

About one in 100 people and nearly nine in 100 over the age of 80 have atrial fibrillation. In most cases, Heckbert says, there are no symptoms and it isn't life threatening, but it can cause palpitations, fainting, fatigue, or even congestive heart failure.

Source: Catharine Paddock, PhD, Medical News Today

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