ADRB1 and atrial fibrillation: Despite differences between the current study and previous literature, the association between the C allele of ADRB1 Arg389Gly and the improvement in testing outcome, along with the higher frequency of the Arg389Gly CC genotype and Arg389Gly C allele in the elite AF population provides evidence that the Arg389Gly C allele may be the preferred allele in AF.