RACE II: Strict vs Lenient Control of Heart Rate in Atrial Fibrillation


2010, Heart Rate Control in patients with Atrial Fibrillation in Preventing CV events, NEJM

RACE II Visual Summary

RACE II was a randomized, prospective, open label, multicenter (33 centers in Netherlands), parallel-group,non-industry sponsored, controlled noninferiority trial investigatingthe role of lenient ratecontrol (HR<110 bpm) versus strict rate control (HR<80 bpm) in preventing cardiovascular events in patients with permanent atrial fibrillation (AF).

614 patients randomized [lenient rate control (n=311) vs. strict rate control (n=303)]. Enrollment was between 2005 & 2007 with follow up for 2-3 years.Patient <= 80 years, with permanent AF for up to 12 months, having mean resting HR > 80 bpm, and on oral anticoagulation therapy or aspirin (if no risk factors for thromboembolic complication present) were included. Those with paroxysmal AF, known contraindications to either strict or lenient rate control, NYHA class IV or HF admission <3 months, cardiac surgery <3 months, stroke, current or planned PPM, ICD or CRT, SSS or AV conduction disturbance, untreated hyperthyroidism, or inability to walk/bike were excluded.

AV nodal blocking agents (beta-blockers, non-dihydropyridine CCBs, or digoxin; alone or in combination) were administered and dose adjusted to achieve target heart rate. More patients in the lenient control arm achieved the target heart rate than in the strict control arm (97.7% vs 75.2%; P<0.001). The mean heart rate in the lenient and strict control arms were 93 & 76 bpm respectively at the end of dose adjustment phase and 85 & 76 bpm respectively at the end of the study follow up period. INR was similar in the two arms.

Primary outcome was the composite of cardiovascular death, HF hospitalization, stroke, systemic embolism, major bleeding and arrhythmic events (syncope, sustained VT, cardiac arrest, life-threatening adverse effect of rate control agents, and implantation of PPM or ICD). Primary outcome was met in 12.9% in the lenient control arm vs 14.9% in the strict control arm [absolute difference of 2% (90% CI -7.6 to 3.5%; P < 0.001); HR 0.84 (90% CI 0.58 to 1.21)].

Individual components of the primary outcome were similar in the two arms. All-cause death, symptoms from AF, number of patients in each NYHA class I to III, frequency of hospitalization and adverse events were similar in the two arms as well. Authors (Van Gelder IC et al) concluded that “in patients with permanent atrial fibrillation, lenient rate control is as effective as strict rate control and is easier to achieve”.