Boston, MA - Pharmacologic rate control in patients with both atrial fibrillation and systolic heart failure should be preferred over the drug- and defibrillation-based rhythm-control approach, concluded investigators from the Atrial Fibrillation and Congestive Heart Failure (AF-CHF) trial, now published in the June 19, 2008 New England Journal of Medicine [1].

Its finding of comparable clinical outcomes for the two methods suggests that clinicians can safely use the far less invasive and usually less costly rate-control approach in a particularly high-risk subset of AF patients for whom the best method was still an open question.

The issue had been essentially settled for the broad population with AF based on a number of randomized trials, the most cited of which is probably AFFIRM [2], but they left open the possibility that one method might prove superior in the many heart-failure patients who have atrial fibrillation.

AF-CHF, which followed more than 1300 patients for a mean of three years, had been presented at the American Heart Association 2007 Scientific Sessions and reported by heartwire at the time.

Many of us believed that you had to force the rhythm control, because you actually did believe it had a favorable impact on mortality. But that's not the case.

"Our results cannot be generalized to patients with heart failure and preserved left ventricular function," caution the authors, led by Dr Denis Roy (Montreal Heart Institute and Université de Montréal, QC). Atrial fibrillation is common in such patients, but little is known in that setting about its therapy or prognostic import, they write.

Still, AF-CHF was a complete wash for the primary end point of cardiovascular mortality as well as the secondary end points of all-cause mortality and worsening HF, in the setting of NYHA class 3-4 heart failure, an LVEF <35%, and ECG-documented AF among patients well-treated with standard HF medications.

In patients with both AF and heart failure, "if they're not terribly symptomatic from the atrial fibrillation, it's fine to then go ahead and use a rate-control strategy," Dr Michael E Cain (University at Buffalo, NY), the coauthor of an editorial accompanying the AF-CHF paper [3], told heartwire. "Many of us believed that you had to force the rhythm control, because you actually did believe it had a favorable impact on mortality. But that's not the case." The AF-CHF trial, he said, "I think has taken care of that question."

Cardiovascular mortality was 27% in the rhythm-control group (n=682) and 25% in the rate-control group (n=694), for a hazard ratio of 1.05 (p=0.67) after adjustment for baseline variables reflecting LV function, heart-failure class, comorbidities, use of implantable devices, duration of AF, renal function, and medical therapy.

Studies must also test the superiority of ablation therapy, as compared with rate control, since ample data show that rate control is an acceptable strategy and one that is almost certainly more cost-effective than any other approach.

On the other hand, hospitalizations were more frequent in the rhythm-control group, the difference reaching significance (46% vs 39%, p=0.001) during the first follow-up year. "This finding probably reflects the need for repeated cardioversion and adjustment of antiarrhythmic therapy [with rhythm control], which is consistent with the results of previous studies," write Roy et al.

An accompanying editorial, coauthored by Cain and Dr Anne B Curtis (University of South Florida, Tampa), makes a case for ablation therapy in patients with both heart failure and AF. Noting that trial after trial has shown no outcomes difference between treatments that aim to control ventricular rate and those that strive to maintain sinus rhythm, they write that "sufficient data are available to lay the blame for these setbacks on the drug-based rhythm-control strategy itself, rather than on the conclusion that sinus rhythm is no better for patients than atrial fibrillation."

Interviewed, Cain considered whether nature actually made a mistake, such that sinus rhythm isn't that important. "Or is it that the treatment doesn't work in some patients, or perhaps the treatment is worse than the disease?" AF ablation "is probably the best approach that we have" to answer those questions, because it achieves rhythm control more effectively than drugs and doesn't have the side effects that detract from the overall effectiveness of drugs.

In their editorial, Cain and Curtis—noting that AF ablation trials are ongoing—observe that "studies must also test the superiority of ablation therapy as compared with rate control, since ample data show that rate control is an acceptable strategy and one that is almost certainly more cost-effective than any other approach."