Feature: Study gives long-term edge to rhythm control

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arrhythmia, electrophsiology - 213.67 Kb

A longstanding debate within the world of arrhythmias has been whether atrial fibrillation (AF) patients fare better with rate or rhythm control. Now, a study published online June 4 in Archives of Internal Medicine may add fuel to the fire after researchers found little differences in mortality within four years of treatment initiation in AF patients administered rate control or rhythm control. However, rhythm control was found to be superior in long-term follow-up.

“Until the publication of the landmark Atrial Fibrillation Follow-up Investigation of Rhythm Management (AFFIRM) trial in 2002, rhythm control (converting patients with AF to normal sinus rhythm) was generally considered superior to rate control,” the authors wrote. “Since then, clinical practice guidelines consider either strategy suitable, although some physicians still prefer the rhythm control strategy.”

Aiming to clear up this controversy, Louise Pilote, MD, MPH, PhD, of Royal Victoria Hospital and McGill University, both in Montreal, and colleagues studied patients 66 years or older who were hospitalized with AF and were not prescribed AF-related drugs in the year prior to admission to evaluate whether the strategies had similar effectiveness in AF patients with longer follow-up.

“Clinical trial results don't always apply to the general population,” Pilote told Cardiovascular Business in an interview. “We wanted to examine the relative effectiveness of rate versus rhythm control in the general population.”

To do so, Pilote et al looked at data from 26,130 patients obtained from the administrative database in Quebec from 1999 to 2007. The researchers measured mortality and followed patients until death or administrative censoring.

The 26,130 patients were followed for a mean of 3.1 years; the authors reported 13,237 deaths in the patient cohort. In total, 24.5 percent were delivered rhythm control treatment. However, the researchers reported a decrease in the use of rhythm control drugs after publication of the AFFIRM trial, which found rhythm control to be superior to rate control. Today either strategy is suitable according to the guidelines, but it seems to continue to be physician preference to use rhythm control.

Of the patients on rate control drugs, 56 percent received beta-blockers, 40 percent digoxin and 30 percent calcium channel blockers. For those on rhythm control, 51 percent received amiodarone and 24 percent sotalol.

It was reported that 3,463 patients in the rhythm control group switched at least once to an alternative treatment compared with 11.2 percent in the rate control group. Mortality data showed that 48.3 percent of patients in the rhythm control group died compared with 50.1 percent in the rate control group.

Crude mortality was reported to be 41.7 percent in the rhythm control group and 46.3 percent in the rate control group after five years of follow-up.

“The weighted standardized survival curves suggest no difference in mortality between the two treatment regimens in the first four years after treatment initiation but diverge later, with the rhythm control group having lower long-term risk,” the authors wrote.

The researchers found a 23 percent reduction in mortality in patients who were newly initiated to rhythm control therapy after eight years of follow-up.

What is the clinical impact of these results? She said that physicians should attempt to make an extra effort to identify patients for rhythm control and try to maintain these patients on rhythm control as long as no complications are seen.

“The first reflex should not be to treat all patients on rate control,” Pilote said.

While the guidelines approve the use of both rhythm and rate control treatment, she said that “patients who are less likely to suffer from complications of rhythm control drugs should be thought of as good candidates.”

Pilote noted that younger patients, those without pulmonary disease and symptomatic patients with atrial fibrillation may best fit the bill.

When asked about costs between the two treatments, she said this is difficult to measure because patients who died did not add any cost to the system. “Cost-effectiveness would favor the drug that is less effective at reducing mortality,” Pilote added.

While Pilote et al did find a greater risk reduction with rhythm control therapy, they urged that the long-term benefits of rhythm control drugs for AF patients will need to be addressed in future studies. However, the