Use of Rhythm Control Strategy in Patients With AF and CHF Not Superior to Rate Control

November 14, 2003

November 14, 2003 — The management of atrial fibrillation (AF) using a rhythm control strategy provides no survival advantage over rate control in patients with congestive heart failure (CHF), according to the results of a retrospective study presented recently at the American Heart Association Scientific Sessions 2003 in Orlando, Florida. [1]

The long debate of whether rhythm control is superior to rate control in AF patients was recently quieted by the findings of several studies, including the large randomized Atrial Fibrillation Follow-up Investigation of Rhythm Management (AFFIRM) trial, [2] in which neither strategy was shown to be superior to the other with respect to mortality. However, as noted by Sana Al-Khatib, MD, Duke University Medical Center (Durham, North Carolina), who presented the findings at the meeting, "only 23% of patients in AFFIRM had CHF and it's not clear how CHF was defined [in the study]." Furthermore, Dr. Al-Khatib told Medscape CRM that because "atrial fibrillation in patients with CHF is associated with a higher mortality, it has been postulated that restoring and maintaining sinus rhythm should improve survival."

No study to date has proven this hypothesis, and many antiarrhythmic medications (with the exception of amiodarone and dofetilide) have been shown to worsen survival of patients with CHF. Thus, according to Dr. Al-Khatib, "many clinicians advocate a strategy of adequate rate control and anticoagulation with warfarin over that of rhythm control with an antiarrhythmic medication."

Study conducted to examine current practice of AF management in patients with CHF

Dr. Al-Khatib and colleagues conducted a study to examine the current practice relating to the management of AF in CHF patients and to determine whether there is any difference in survival between a rate control or rhythm control strategy in these patients.

They screened the Duke Cardiovascular Disease Database -- a collection of extensive demographic, clinical, and laboratory data on all patients who undergo cardiac catheterization at the Duke University Medical Center -- to identify patients with a history of AF, a history of CHF, and ejection fraction (EF) < 50% between 1995 and 2002. Patients with congenital heart disease or with cardiogenic shock were excluded from the study. In addition to recording a patient's in-hospital clinical experience, the database collects information on symptoms at time of cardiac procedures, diagnoses, electrocardiographic findings, medications, severity of coronary artery disease (CAD), and measures of left ventricular function. The database also incorporates post-hospital follow-up at 6 months, 1 year, and annually thereafter.

A total of 1009 patients met inclusion criteria, and patients were classified according to management strategy -- rhythm control (any class I or class III antiarrhythmic medication; n = 491) vs rate control (beta-blockers, calcium-channel blockers, and/or digoxin and no antiarrhythmic drug therapy; n = 518).

Rate control patients less likely to receive warfarin, diuretic, or beta-blocker therapy than rhythm control patients

There was no difference in the percentage of male patients, median EF (~ 34%), or the severity of CHF between the 2 groups. However, patients in the rate control arm tended to be older, were more likely to have angina, cerebrovascular disease, and advanced CAD than were patients in the rhythm control arm. In addition, rate control patients were significantly less likely to receive beta-blocker therapy than their rhythm control counterparts (70% vs 77%, respectively) and were also less likely to be treated with warfarin (47% vs 62%), a diuretic, or an angiotensin-converting enzyme inhibitor.

The majority of rhythm control patients were treated with amiodarone. Seventeen percent of patients were treated with a class IA antiarrhythmic drug, 16% with sotalol, 1.4% received propafenone, and .6% dofetilide. Of interest, Dr. Al-Khatib reported that the use of antiarrhythmic medications increased dramatically from 30.3% in 1995 to 67.5% in 2002.

At median follow-up of 1.3 years, 42% of all study patients (n = 423) died; 49% were treated with rate control therapy and 35% were treated with rhythm control therapy. The 1-year mortality rates were identical in the 2 groups (both 21%). At 2 years, the mortality rates increased, but there was still no significant difference between the rate and rhythm control groups (31% vs 28%, respectively).

After adjusting for medications and baseline variables, no significant difference in mortality was found between the 2 groups (hazard rate, 1.03; 95% confidence interval, 0.83-1.27; P = .79).

Still too many patients not receiving adequate anticoagulation therapy

Overall, the Duke researchers found that clinicians did not favor one strategy over another in patients with AF and CHF; approximately 50% of patients received rhythm control therapy. Dr. Al-Khatib expressed disappointment at the low rate of patients receiving warfarin therapy, particularly in the rate control arm, which she stated was even lower than reported in other studies.

As with the results of the AFFIRM study, the Duke researchers found that a rhythm control strategy confers no survival advantage over rate control in patients with CHF and AF. However, Dr. Al-Khatib emphasized that the Duke findings highlight the need for prospective randomized studies to definitively answer the question of whether rhythm control therapy is superior to rate control therapy in patients with CHF and added that "these future studies should not only look at the effect of these 2 strategies on survival, but they should also investigate the effect of these strategies on patients' quality of life."

AF-CHF study to answer more questions

One such study, the Atrial Fibrillation and Congestive Heart Failure (AF-CHF) trial, is already underway at 109 sites in the United States, Canada, South America, Europe, and Israel. [3]

With an anticipated total enrollment of 1450 patients with AF, CHF, and EF <= 35%, the AF-CHF trial will randomize patients to either rhythm control (electrical cardioversion combined with antiarrhythmic drugs) or rate control (beta-blockers, digoxin, or pacemaker and atrioventricular nodal ablation) to compare the outcome of the 2 treatment strategies.

References
  1. Al-Khatib SM, Shaw L, Shah M, O'Connor C, Califf RM. Atrial fibrillation in congestive heart failure: Is rhythm control therapy superior to rate control therapy? Program and abstracts of the American Heart Association 2003 Annual Meeting; November 9-12, 2003; Orlando, Florida. Abstract.

  2. The Atrial Fibrillation Follow-up Investigation of Rhythm Management (AFFIRM) Investigators. A comparison of rate control and rhythm control in patients with atrial fibrillation. N Engl J Med. 2002;347:1825-1833.

  3. Rationale and design of a study assessing treatment strategies of atrial fibrillation in patients with heart failure: The Atrial Fibrillation and Congestive Heart Failure (AF-CHF) trial. Am Heart J. 2002;144:597-607.

By Staff Writer, Medscape CRM
Reviewer: Albert A. Del Negro, MD

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