An observational study in which researchers compared whether the rhythm in which drugs are administered to patients with atrial fibrillation (AF) is more effective than the rate control with regard to mortality in these patients, demonstrated that after four years of treatment there is only a small difference within in mortality. However, the study published Online First in Archives of Internal Medicine revealed that the rhythm control may be linked to better long-term outcomes.
According to background information of the study, around 2.3 million Americans and 250,000 Canadians suffer from AF, which is a rapid, irregular heartbeat that requires complex treatments that often involves rate control agents, antiarrhythmic or anticoagulant drugs and/or ablative techniques, i.e. a procedure involving a catheter to eliminate the anatomic source of the atrial fibrillation.
The researchers write:
"Controversy continues concerning the choice of rhythm control vs. rate control treatment strategies for atrial fibrillation (AF). A recent clinical trial showed no difference in five-year mortality between the two treatments. We aimed to determine whether the two strategies have similar effectiveness when applied to a general population of patients with AF with longer follow-up."
For their study, Raluca Ionescu-Ittu, Ph.D., of the Harvard School of Public Health in Boston and team selected patients above the age of 66 years from a population-based Canadian database in Quebec from 1999 to 2007 who received no AF-related drugs in the year before they were hospitalized, but who received AF drugs within seven days of being discharged from hospital.
The researchers state:
"We found that with increasing follow-up time the mortality among the patients who newly initiated rhythm control therapy gradually decreased relative to those who initiated rate control drugs, reaching 23 percent reduction after eight years of follow-up," noting that recent clinical trials that compared the two treatments "concluded that there are no differences in mortality between the two treatment strategies."
They conclude writing: "For the first four years after treatment initiation, our results in a population-based sample are similar to the results from the recent clinical trials. In addition, we found a tendency toward a long-term protective effect for rhythm control drugs. The long-term benefits of rhythm control drugs in AF found in this study need to be assessed in future studies."
Thomas A. Dewland, M.D., and Gregory M. Marcus, M.D., M.A.S., from the University of California in San Francisco, asked in a linked editorial: "How do we best interpret this unexpected result given contrary evidence from prior randomized trials?"
"Although the findings of Ionescu-Ittu et al are provocative, they are insufficient to recommend a universal rhythm control strategy for all patients with AF. Randomization is a powerful tool that unfortunately cannot be reliably reproduced with statistical modeling."