Rate control efficacy in permanent atrial fibrillation:a comparison between lenient versus strict rate control in patients with and without heart failure. Background, aims, and design of RACE II

BACKGROUND: Recent studies demonstrated that rate control is an acceptable alternative for rhythm control in patients with persistent atrial fibrillation (AF). However, optimal heart rate during AF is still unknown.OBJECTIVE: To show that in patients with permanent AF, lenient rate control is not inferior to strict rate control in terms of cardiovascular mortality, morbidity, neurohormonal activation, New York Heart Association class for heart failure, left ventricular function, left atrial size, quality of life, and costs.METHODS: The RACE II study is a prospective multicenter trial in The Netherlands that will randomize 500 patients with permanent AF (< or = 12 months) to strict or lenient rate control. Strict rate control is defined as a mean resting heart rate < 80 beats per minute (bpm) and heart rate during minor exercise < 110 bpm. After reaching the target, a 24-hour Holter monitoring will be performed. If necessary, drug dose reduction and/or pacemaker implantation will be performed. Lenient rate control is defined as a resting heart rate < 110 bpm. Patients will be seen after 1, 2, and 3 months (for titration of rate control drugs) and yearly thereafter. We anticipate a 25% 2.5-year cardiovascular morbidity and mortality in both groups.RESULTS: Enrollment started in January 2005 in 29 centers in The Netherlands and is expected to be concluded in June 2006. Follow-up will be at least 2 years with a maximum of 3 years.CONCLUSION: This study should provide data how to treat patients with permanent AF.