A study published in the Archives of Internal Medicine indicates that in the long-term, rhythm control for atrial fibrillation may be associated with lower mortality than rate control.
Raluca Ionescu-Ittu, Harvard School of Public Health, Harvard University, Boston, USA, and others reported that after the AFFIRM (Atrial Fibrillation Follow-up Investigation of Rhythm Management) study, which did not show a mortality benefit of rhythm control compared with rate control in patients with atrial fibrillation, there has some controversy over whether rhythm control or rate control should be used. Ionescu-Ittu et al noted that some physicians questioned “the generalisability of the AFFIRM trial results to the general population.”
The aim of Ionescu-Ittu’s study was to compare the effects of rhythm control with the effects of rate control on reducing mortality in a retrospective population-based cohort of patients with atrial fibrillation. Of 26, 130 eligible patients, 6,402 were initiated on rhythm control treatment and 19,728 were initiated on rate control. At five years, no difference in mortality rates between the two groups was identified. However, in a restricted sample of patients who survived more than five years and after resetting the “follow-up time to zero at year five”, morality was lower in patients in the rhythm control group. They reported: “In the analysis that accounted for treatment crossovers by modelling the ‘current treatment’, the long-term mortality reduction was even stronger for patients initiated and maintained rhythm control therapy relative to those who initiated and maintained rate control therapy at one, five, and eights after treatment initiation.”
Ionescu-Ittu et al added that after eight years of follow-up, patients initiated on rhythm control therapy were associated with a 23% reduction in mortality compared with patients initiated on rate control.
The authors stressed that there were several factors that could explain the differences in results between their study and clinical studies, such as AFFIRM-for example, there were higher crossover rates in their study compared with the AFFIRM study. However, they added that the differences could, at least in part, be due to the fact they had a longer follow-up time and used a more flexible analysis. They concluded the results of their study indicated that after the first four years of treatment, rhythm control may be more effective than rate control. As this risk reduction was more pronounced among patients who maintained their initial use of rhythm control therapy, Ionescu-Ittu et al wrote: “The results suggest that the development of antiarrhythmic drugs were fewer adverse effects but retained or improved efficacy may result in important gains in the survival of patients with atrial fibrillation.”
In an accompanying editorial, Thomas Dewland and Gregory Marcus, both from Division of Cardiology, Section of Electrophysiology, University of California, San Francisco, USA, called Ionescu-Ittu’s findings “procactive” but added that they were “insufficient to recommend a universal rhythm control strategy for all patients.”