A COMPARISON OF RATE CONTROL AND RHYTHM CONTROL IN PATIENTS WITH ATRIAL FIBRILLATION
Wyse DG, Waldo AL, DiMarco JP, Domanski MJ, Rosenberg Y, Schron EB, Kellen JC, Greene HL, Mickel MC, Dalquist JE, Corley SD; 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. 2012 Dec 5;347(23):1825-33. doi: 10.1056/NEJMoa021328. PMID: 12466506.
- A-fib: MC sustained arrhythmia.
- Problem: poorly controlled/irregular ventricular rate
- Tx goal: NSR maintenance
- There are two approaches to the treatment of atrial fibrillation: one is cardioversion and treatment with antiarrhythmic drugs to maintain sinus rhythm, and the other is the use of rate-controlling drugs, allowing atrial fibrillation to persist. In both approaches, the use of anticoagulant drugs is recommended.
- Initial therapy – “Rhythm Control”: (NSR is the goal)
~cardioversion ⇢ Antiarrhythmic drugs
- Alternative therapy – “Rate control”: control ventricular response with AV node blocking drugs
~ AV Junction ablation
- Rate control permits use of drugs less toxic than antiarrhythmics
- Anticoagulation is important in both (esp rate control)
- This is a randomized multicenter comparison of these two strategies tracking mortality as a main outcome
- N = 4060 pts (70 +/- 9 y/o)
~ Representative of majority of patients with A-Fib
The mean follow- up time was 3.5 years, with a maximum of 6 years.
- Rhythm control:
~ Antiarrhythmic drug used was chosen by the treating physician. Attempts to maintain sinus rhythm could include cardioversion as necessary. The following drugs were acceptable for use, according to the protocol: amiodarone, disopyramide, flecainide, moricizine, procainamide, propafenone, quinidine, sotalol, and combinations of these drugs. When dofetilide became available, it also could be used.
- 23.8% mortality
- Rate control:
~Drugs that were acceptable in the protocol for this purpose were beta-blockers, calcium-channel blockers (verapamil and diltiazem), digoxin, and combinations of these drugs. Heart-rate control during atrial fibrillation was assessed both at rest and during activity, which usually consisted of a six-minute walk. The goal was a heart rate not higher than 80 beats per minute at rest and not higher than 110 beats per minute during the six-minute walk test.
- 21.3% mortality
- After standard approaches to treatment were exhausted, but not before the failure of at least two trials of either a rhythm-control drug or a rate-control drug, patients could be considered for non- pharmacologic therapy, such as radio-frequency ablation, a maze procedure, and pacing techniques, as appropriate to their randomized strategy.
- The goal for anticoagulation with warfarin was an international normalized ratio (INR) of 2.0 to 3.0. In the rhythm-control group, continuous anticoagulation was encouraged but could be stopped at the physician’s discretion if sinus rhythm had apparently been maintained for at least 4, and preferably 12, consecutive weeks with antiarrhythmic-drug therapy. In the rate-control group, continuous anticoagulation was mandated by the protocol
To sum it up:
- Both groups: stroke when subtherapeutic INR
- Continuous anticoagulation is warranted in all patients with atrial fibrillation and risk factors for stroke, even when sinus rhythm appears to be restored and maintained
- Rhythm control offers no survival advantage over rate control
- The patients in the rhythm-control group (cardioversion) were significantly more likely to be hospitalized and have adverse drug effects than those in the rate-control group
- Results probably cannot be generalized to younger patients without risk factors for stroke (i.e., patients with primary, or “lone,” atrial fibrillation), particularly those with paroxysmal atrial fibrillation.