Lessening medication for atrial fibrillation does not reduce side effects

October 14, 2008

Reducing how often a patient receives amiodarone, a medication used for suppressing atrial fibrillation (irregular heart beat) but which causes side effects, did not decrease the overall amount of amiodarone-related and heart disease related side effects, but did increase the rate of atrial fibrillation recurrence and the risk of death from all causes and cardiovascular hospitalizations, according to a study in the October 15 issue of JAMA.

The adverse events caused by amiodarone are mostly associated with high daily dosages and long-term therapy, according to background information in the article.

Sheba Ahmed, M.D., of the University of Groningen, Netherlands, and colleagues conducted a study to compare the effects of episodic vs. continuous amiodarone treatment on major events related to amiodarone use and to determine if episodic treatment could effectively suppress atrial fibrillation. The trial included 209 patients with recurrent atrial fibrillation who were randomly assigned to receive either episodic or continuous amiodarone treatment. Episodic amiodarone treatment was discontinued after a month of sinus rhythm (the normal regular rhythm of the heart) and reinitiated if atrial fibrillation relapsed. In the continuous treatment group amiodarone was maintained throughout.

After a median (midpoint) follow-up of 2.1 years, 51 (48 percent) of the patients in the episodic vs. 64 (62 percent) in the continuous treatment group had sinus rhythm. The researchers found that in the episodic group, more atrial fibrillation recurrences occurred (80 percent) than in the continuous treatment group (54 percent). The incidence of the primary outcome for the study—any amiodarone or underlying heart disease–related major event—was 35 percent in the episodic vs. 33 percent in the continuous treatment group. There were differences in the incidence of amiodarone major events (19 percent, episodic vs. 24 percent, continuous) and underlying heart disease–related major events (16 percent, episodic vs. 9 percent, continuous), although these differences did not reach statistical significance. All-cause deaths and cardiovascular hospitalizations were higher among those receiving episodic treatment (53 percent vs. 34 percent).

"Considering the above, episodic amiodarone treatment cannot be advocated for most patients with persistent atrial fibrillation," the authors write. "This study shows that episodic amiodarone treatment—in contrast to our expectations—has no clinical advantage over continuous treatment because it did not lower morbidity in patients with persistent atrial fibrillation over 2 years of follow-up."

Source: JAMA and Archives Journals