Bone drugs may raise risk of irregular heartbeat

The risk of developing a serious irregular heartbeat, resulting in hospitalization or death, is substantially higher among bisphosphonate users than nonusers, results of a study indicate.

Bisphosphonates are medications used to strengthen bones. They are often prescribed to people with the bone-thinning disease osteoporosis. Two examples of bisphosphonates are alendronate (sold as Fosamax) and zoledronic acid (sold as Zometa).

A team at Jackson Memorial Hospital in Miami, Florida, reviewed 1,646 randomized controlled trials in which bisphosphonates were compared with placebo for the treatment of osteoporosis and in which atrial fibrillation was reported as an adverse event.

Atrial fibrillation—the rapid and uncoordinated beating of the upper chambers of the heart—is a fairly common disorder that has been linked to an increased risk of blood clots, stroke, and early death, if not controlled.

Dr. Jennifer Miranda and colleagues identified three studies involving a total of 16,322 patients. Between 76 percent and 100 percent of subjects in the studies were older women taking either Fosamax or Zometa for osteoporosis.

During an average follow-up lasting 1 to 2 years, between 2.5 percent and 3.0 percent of patients taking bisphosphonates developed atrial fibrillation, and approximately 2 percent of them experienced serious atrial fibrillation, defined as an event that resulted in either hospitalization or death, Miranda reported.

Bisphosphonate users were 19 percent more likely to develop atrial fibrillation than nonusers, which was not statistically significant, but their odds of developing serious atrial fibrillation 68 percent higher, which was “highly statistically significant,” the researcher stated.

Although Zometa and Fosamax were the only two agents evaluated, Miranda said it is logical that risk of atrial fibrillation would extend to other bisphosphonates.

“The FDA is interested in studying this further,” Miranda said. “They have put information on their website about it.” She reported the findings this week at the 74th annual international scientific assembly of the American College of Chest Physicians.

“In patients with risk factors for atrial fibrillation, clinicians should be more cautious when choosing treatments for osteoporosis and weigh the risks against the benefit of decreased fracture risk,” Miranda said.

By Martha Kerr
PHILADELPHIA (Reuters Health)