GRK5 and systolic heart failure: Considering that ADRB1 and GRK5 polymorphisms were represented differently among ethnicities, and influenced the β-blocker treatment effect with systolic heart failure (SHF), thus our study was designed to identify whether GRK5 Gln41Leu and ADRB1 Arg389Gly polymorphisms would affect on SHF in Chinese population.