Impact of β-2 Thr164Ile and combined β-adrenergic receptor polymorphisms on prognosis in a cohort of heart failure outpatients

Abstract

Genetic polymorphisms of adrenergic receptors (ARs) have been associated with the development, progression, and prognosis of patients with heart failure (HF), with few data for the Brazilian population. We evaluated the role of the beta2-AR Thr164Ile polymorphism at codon 164 on prognosis in a prospective study on 315 adult Brazilian HF patients, predominantly middle-aged Caucasian men in functional class I-II, with severe left ventricular systolic dysfunction. Genomic DNA was extracted from peripheral blood and beta2-AR164 genotypes were detected by PCR followed by restriction fragment length analysis. During a median follow-up of 3 years, 95 deaths occurred and 57 (60%) were HF-related. Unexpectedly, Ile164 carriers (N = 12) had no HF-related events (log-rank P value = 0.13). Analysis using genotype combination with beta1-AR polymorphisms at codons 49 and 389 identified patients with favorable genotypes (Thr164Ile of beta2-AR, Gly49Gly of beta1-AR and/or Gly389Gly of beta1-AR), who had lower HF-related mortality (P = 0.01). In a Cox proportional hazard model adjusted for other clinical characteristics, having any of the favorable genotypes remained as independent predictor of all-cause (hazard ratio (HR): 0.41, 95%CI: 0.17-0.95) and HF-related mortality (HR: 0.12, 95%CI: 0.02-0.90). These data show that the beta2-AR Thr164Ile polymorphism had an impact on prognosis in a Brazilian cohort of HF patients. When combined with common beta1-AR polymorphisms, a group of patients with a combination of favorable genotypes could be identified.