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| |  Lenient Heart-Rate Control an Option for Patients With Atrial Fibrillation: Presented at ACC By Walter Alexander ATLANTA -- March 16, 2010 -- Among patients with permanent atrial fibrillation (both low- and high-risk), lenient rate control may be adopted as first-choice rate-control strategy, according to results from the Rate Control Efficacy in Permanent Atrial Fibrillation II (RACE II) study. Isabelle C. Van Gelder, MD, University Medical Center Groningen, Groningen, the Netherlands, reported the findings here on March 15 at the 59th Annual Scientific Sessions of the American College of Cardiology (ACC) during a Late-Breaking presentation. Dr. Van Gelder noted that atrial fibrillation is not benign. Patients may be symptomatic and are vulnerable to stroke and heart failure. While rate control has become front-line therapy for atrial fibrillation, optimal heart-rate control levels have not been established. RACE II is the first randomised trial to investigate the best level of heart-rate control in patients with atrial fibrillation. It tested whether therapy aimed at achieving a resting heart rate of <110 beats per minute (bpm) in patients with atrial fibrillation was noninferior to therapy targeted at a resting heart rate of <80 bpm. Participants (n = 614) were aged <=80 years with permanent atrial fibrillation for up to 1 year, with heart rates >80 bpm. All were receiving oral anticoagulation. The primary endpoint was a composite of cardiovascular mortality, heart failure hospitalisation, stroke, systemic emboli, major bleeding, syncope, sustained ventricular tachycardia, cardiac arrest, life-threatening adverse effects of rate control drugs, pacemaker implantation for bradycardia, or implantable cardioverter defibrillator implantation for ventricular arrhythmias. Patients were randomised to lenient (n = 311) or strict (n = 303) rate control, with lenient defined as a heart rate determined by 12-lead electrocardiogram of <110 bpm at rest and strict control was defined as heart rates <80 bpm at rest and <110 bpm during moderate exercise (defined as 25% of maximal). Treatment consisted of beta blockers, non-dihydropyridine calcium-channel blockers, and digoxin, alone or in combination with dosages increased or drugs combined until the heart rate target was achieved. During months 12 to 36 of the 3-year study, heart rates remained significantly lower (P < .001) in the strict-control group (~85 vs ~75 bpm). Rate-control targets were met in 98% of patients in the lenient-control group and in 67% of the strict-control group. Achieving targets required a far lower visit total in the lenient-control group (75 vs 684 visits; P < .001). The primary combined outcome was reported in 38 patients in the lenient-control group and 43 patients in the strict-control group. The estimated cumulative incidence of these events at 3 years was 12.9% in the lenient-control group and 14.9% in the strict-control group (P < .001 for the prespecified noninferiority margin). Symptom and adverse event frequencies were similar between the 2 strategies. Dr. Van Gelder concluded, “In patients with permanent atrial fibrillation, lenient rate control is as effective as strict control and easier to achieve.” In an interview, Ray Gibbons, MD, Mayo Clinic, Rochester, Minnesota, expressed reservations over the fact that the resting heart rate of 110 bpm allowed in the lenient group was high and is thought to be a risk for tachycardia-induced heart failure, and that the baseline symptom rate overall was low and may reflect exclusion of patients progressing to heart failure within the year. Nonetheless, he concluded, “RACE II is an important study. I think it will prompt careful review and likely change in the next edition of guidelines.” [Presentation title: The Rate Control Efficacy in Permanent Atrial Fibrillation (RACE II). Late-Breaking Clinical Trials II]
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