Long-term rhythm, not rate, control may prolong life with AF

By Sarah Guy

Rhythm control therapy for atrial fibrillation (AF) may improve survival rates compared with rate control therapy when used long term, show study results published in the Archives of Internal Medicine.

While patients treated with either type of drug had similar mortality rates within 4 years of treatment initiation, by 8 years, the mortality rate had dropped by almost a quarter among rhythm control- compared with rate control-treated patients, say the researchers.

The reduction in risk for death was even more pronounced in patients who had maintained the treatment they were initially assigned to, indicating that "the use of rhythm control therapy may be beneficial for patients with AF in whom antiarrhythmic drugs are effective and well tolerated."

"The results suggest that the development of antiarrthymic drugs with fewer adverse effects but retained or improved efficiency may result in important gains in the survival of patients with AF," suggest Louise Pilote (Royal Victoria Hospital in Montreal, Quebec, Canada) and co-authors.

Their study included 26,130 Canadian patients aged at least 66 years old who were newly diagnosed with AF during hospitalization between 1999 and 2007. All initiated treatment within 7 days of discharge.

A total of 24.5% initiated rhythm control treatment, with amiodarone (51.0%) and sotalol (24.0%) the most common prescriptions. Beta-blockers (56.0%), digoxin (40.0%), and/or calcium-channel blockers (30%) were the most common rate-control drugs prescribed.

After a short-term increase in mortality among rhythm control-treated patients, mortality rates were comparable between groups for the first 3 years after treatment initiation.

By contrast, after 5 years posttreatment, Pilote and colleagues found a steady decrease in mortality among rhythm control-treated patients.

Specifically, the risk for mortality among rhythm control patients was 7% and 3% higher at 6 months and 1 year, respectively, versus rate control patients, whereas it was 5%, 11%, and 23% less than rate control patients after 3, 5, and 8 years of treatment.

After accounting for treatment crossover, the research team found that long-term mortality reduction was even higher for patients who initiated and maintained rhythm control therapy. The risk for mortality at 5 and 8 years was 24% and 39% less in the rhythm than the rate control group.

While recent trials have indicated no difference in mortality rates between the two therapy types, Pilote and co-researchers believe this could be because patients who participate in trials are not representative of patients in the general population, which is represented in their study.

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