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RATE CONTROL MATCHES RHYTHM CONTROL FOR AFIB

Atrial fibrillation (AF) can be managed with 1 of 2 strategies. A rhythm-control strategy uses antiarrhythmic drugs to maintain sinus rhythm (SR), with possible eventual discontinuation of anticoagulation. A rate-control strategy allows AF to persist but slows ventricular rate with atrioventricular-nodal blocking agents or ablation of the atrioventricular junction and pacemaker implantation (anticoagulation is continued). In 2 multicenter, randomized trials, researchers compared the 2 strategies.

Researchers in the U.S. and Canada randomized 4060 AF patients (minimum age, 65; mean, 70) to either rhythm control or rate control; in all patients, AF was likely recurrent and warranted treatment, and risk for stroke was high. Rhythm control involved attempts to achieve SR with at least 2 antiarrhythmic agents; 63% of rhythm-control patients received amiodarone at some point during the study. Rate control allowed use of all standard drugs that slow the ventricular response (e.g., beta-blockers, calcium-channel blockers, digoxin), with heart-rate (HR) goals of 80 bpm at rest and 110 bpm on the 6-minute walk test. Warfarin was used for anticoagulation in both groups; warfarin discontinuation was allowed in the rhythm group if SR was maintained for 4 weeks. Mean follow-up was 3.5 years (maximum, 6).

Five-year estimates showed that 63% of the rhythm group and 35% of the rate group were in SR. Mortality rates were 24% and 21%, respectively (a nonsignificant difference). The annual rate of ischemic stroke was about 1% in both groups, with a slightly higher rate in the rhythm group; most strokes occurred in patients who stopped warfarin or had subtherapeutic INRs. Rhythm patients had significantly higher rates of hospitalization and adverse drug effects.

Dutch researchers randomized 522 patients (mean age, 68) with persistent AF or atrial flutter lasting <1 year to rhythm control (cardioversion initially, then sotalol, and then [as needed] flecainide or propafenone, followed by adjunctive amiodarone) or to rate control (target resting HR, <100 bpm). More than 90% of patients in both groups had risk factors for stroke.

By follow-up (mean, 2.3 years), 39% of the rhythm group and 10% of the rate group were in SR. Incidence of the primary composite endpoint (cardiovascular death, heart failure, thromboembolic complications, bleeding, pacemaker implantation, or severe adverse antiarrhythmic-drug effects) was 23% in the rhythm group and 17% in the rate group (a nonsignificant difference). Thromboembolic complications were more common in the rhythm group (7.9% vs. 5.5%) but not significantly so; most were associated with warfarin discontinuation or subtherapeutic INRs.

Comment: These 2 studies reveal that rate control is an acceptable alternative to rhythm control in older, minimally symptomatic afib patients. The slightly higher rates of thromboembolism with rhythm control in both studies call attention to the importance of maintaining anticoagulation, even in patients whom rhythm control has apparently returned to SR. An accompanying editorial cautions that these findings may not apply to patients with first episodes of AF, to highly symptomatic AF patients, and to lower-risk patients (e.g., those with lone AF). Also remember that catheter ablation is emerging as a potentially curative approach to AF. Further study must show whether catheter ablation can achieve better maintenance of SR, better prevention of death and stroke, and better quality of life than antiarrhythmic therapy can.

— Hugh Calkins, MD

Published in Journal Watch Cardiology January 2, 2004

Citation(s):

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 Dec 5; 347:1825-33.

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• Medline abstract (Free)

Van Gelder IC et al. for the Rate Control versus Electrical Cardioversion for Persistent Atrial Fibrillation Study Group. A comparison of rate control and rhythm control in patients with recurrent persistent atrial fibrillation. N Engl J Med 2002 Dec 5; 347:1834-40.

• Original article (Subscription may be required)
• Medline abstract (Free)

Falk RH. Management of atrial fibrillation -- Radical reform or modest modification? N Engl J Med 2002 Dec 5; 347:1883-4.

• Original article (Subscription may be required)
• Medline abstract (Free)