Impact of β1-Adrenergic Receptor Polymorphisms on Susceptibility to Heart Failure, Arrhythmogenesis, Prognosis, and Response to Beta-Blocker Therapy

Beta1-adrenergic receptor polymorphisms have been implicated with inconsistent results in the pathogenesis, clinical presentation, and prognosis of patients with heart failure (HF). The impact of 2 functional polymorphisms (β1-Arg389Gly and β1-Ser49Gly) on HF susceptibility, arrhythmogenesis, and prognosis was evaluated in Brazilian outpatients. Genotyping at codons 389 and 49 was performed using polymerase chain reaction with restriction fragment length polymorphism analysis in 201 outpatients with systolic HF and 141 apparently healthy controls. Enrolled patients were followed up at the HF clinic, and vital status was evaluated using electronic hospital records, telephone contact, and a local death certificate database. Allele frequencies were similar between patients with HF and controls, with neither polymorphism related to HF susceptibility. The β1-389Gly homozygotes had significantly less nonsustained ventricular tachycardia on Holter monitoring (17% vs 48% for Arg/Arg patients; p = 0.015) and improved HF-related survival, with no events after a median follow-up of 40 months (log-rank statistics = 0.025). The negative impact of β1-389Arg allele on HF-related survival was substantially reduced using high-dose β-blocker therapy (80% survival for high-dose vs 42% for low-dose β blockers or nonusers; log-rank statistics = 0.0003). The β1-Ser49Gly polymorphism was not associated with nonsustained ventricular tachycardia or HF prognosis. In conclusion, β1-Arg389Gly and β1-Ser49Gly polymorphisms had no influence on HF susceptibility. However, the Gly389 allele was associated with a lower prevalence of ventricular arrhythmias and better HF-related survival. A pharmacogenetic interaction is suggested because β blockers were more effective in β1-389Arg allele carriers.