This pharmacogenetic substudy of the prospective, double-blind, randomized CIBIS-ELD trial determined the impact of the ?1-adrenoceptor Arg189Gly polymorphism on heart-rate responses to bisoprolol or carvedilol in elderly patients with heart failure (421 with sinus rhythm, 107 with atrial fibrillation). Patients were randomized 1:1 to bisoprolol or carvedilol with a fortnightly dose-doubling scheme and guideline target doses. Patients with sinus rhythm responded essentially identically to bisoprolol and carvedilol, independent of genotype. Atrial fibrillation patients homozygous for Arg389 had a much smaller response to carvedilol than carriers of at least one Gly389 allele (mean difference 12 bpm, P < 0.00001). Carvedilol up to 2 × 12.5 mg did not reduce heart rate in Arg389Arg homozygotes at all. Interestingly, the immediate response to carvedilol did not differ between genotypes. The Arg389Gly polymorphism has a major impact on the heart-rate response to carvedilol (but not bisoprolol) in patients with heart failure plus atrial fibrillation.
