CardioExchange Archive

CardioExchange, an NEJM practice community for medical professionals dedicated to improving cardiac patient care, was active from 2009 to 2015. CardioExchange fostered discussion between clinicians from across the globe.

June 4th, 2012

Observational Study Finds Possible Long-Term Mortality Advantage for Rhythm Control Drugs in Atrial Fibrillation

Challenging a decade-old influential trial, a large observational study of patients with atrial fibrillation (AF) suggests that rhythm control drugs may outperform rate control drugs after 4 years.

Raluca Ionescu-Ittu and colleagues analyzed data from 26,130 patients 66 years or older diagnosed with AF in Quebec, Canada. Patients were followed for a mean of 3.1 years and for a maximum of 9 years. In apparent agreement with the AFFIRM trial, the investigators observed a small early increase in mortality associated with rhythm control therapy, followed by similar mortality between the groups until year 4. After year 4, however, mortality was lower in the rhythm control arm.

Total unadjusted mortality

  • Rhythm control: 48.3%
  • Rate control: 50.1%

Unadjusted mortality at 5 years:

  • Rhythm control: 41.7%
  • Rate control: 46.3%

Adjusted hazard ratios for rhythm control at:

  • 6 months: 1.07 (1.01-1.14)
  • 1 year: 1.03 (0.95-1.11)
  • 3 years: 0.95 (0.90-1.02)
  • 5 years: 0.89 (0.81-0.96)
  • 8 years: 0.77 (0.62-0.95)

The authors point out numerous differences between their study population and the AFFIRM study population, including the fact that their subjects were older, were more likely to be female and to have CHF, and were more likely to receive beta-blockers in the rate control group. Acknowledging the limitations of observational studies, they write that “the long-term benefits of rhythm control drugs in AF found in this study need to be assessed in future studies.”

In an accompanying editorial, Thomas Dewland and Gregory Marcus write that the results of the observational study are “provocative” but “insufficient to recommend a universal rhythm control strategy for all patients with AF.” They remind their readers, however, “that no clinical trial has definitively shown that maintenance of sinus rhythm is inferior to rate control, and expert consensus recommends a rhythm control strategy for individuals with arrhythmia-attributable symptoms.”

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