endothelin-1 and bucindolol

Beta-blocker therapy has become a mainstay therapy for the over 5 million patients with chronic heart failure in the United States. Variation in clinical response to beta-blockers is a well-known phenomenon and may be because of genetic differences between patients. We hypothesized that variation in genes of the endothelin system mediate the clinical response to beta-blockers in heart failure.. Single nucleotide polymorphisms (SNPs) in six endothelin system genes were genotyped in 309 heart failure patients in a randomized trial of bucindolol versus placebo therapy. We adjusted for multiple comparisons and tested for association between genotype and time to two prospective endpoints.. Nine SNPs were sufficiently common to undergo statistical analysis. The SNPs had no significant effect on prospective outcomes in the placebo group, or on the primary endpoint of time to death in either arm. Two SNPs (IVS-4 G/A and Lys198Asn) in the endothelin-1 gene, however, predicted time to the combined endpoint of heart failure hospitalization or all-cause death in bucindolol-treated patients. The alleles at these SNPs were in tight linkage disequilibrium appearing on either of two complementary haplotypes. A 'dose-response' trend was observed, with participants carrying the rarer haplotype having the highest hazard ratios as compared to the relative 'protective' effect of the common haplotype.. A common endothelin-1 gene haplotype may be a pharmacogenetic predictor of a favorable clinical response to beta-blocker therapy in heart failure patients. The existence of a less common 'high-risk' haplotype could identify a subpopulation of heart failure patients destined to respond poorly to beta-blocker therapies.

Topics: Adrenergic beta-Antagonists; Aged; Aspartic Acid Endopeptidases; Endothelin-1; Endothelin-Converting Enzymes; Endothelins; Female; Haplotypes; Heart Failure; Humans; Linkage Disequilibrium; Male; Metalloendopeptidases; Middle Aged; Models, Genetic; Pharmacogenetics; Polymorphism, Single Nucleotide; Propanolamines; Proportional Hazards Models; Receptors, Endothelin

Serial neurohormones may serve as markers of efficacy of congestive heart failure (CHF) therapy. We measured serial plasma big-endothelin (Big-ET), ET-1, N-terminal atrial natriuretic peptide, and brain natriuretic peptide (BNP) in 206 patients randomized to bucindolol or placebo in Beta-Blocker Evaluation of Survival Trial (BEST).. Neurohormones were measured at baseline and 3 and 12 months. At baseline, BNP and Big-ET levels were greater in New York Heart Association (NYHA) Class IV than in Class III patients (median 122 pg/mL versus 447 pg/mL, P = .001; and 20.0 pg/mL versus 9.9 pg/mL, P = .003), and in patients with left ventricular ejection fraction (LVEF) < or = 20% compared with LVEF > 20% (median 211 pg/mL versus 99.1 pg/mL; and 12.9 pg/mL versus 8.0 pg/mL, both P = .003). Big-ET and BNP were the strongest predictors of the composite end point of CHF hospitalization or death. LVEF at 12 months correlated inversely with 12-month BNP levels (r = -0.41, P = .0001). Bucindolol had no effect on neurohormones except that bucindolol treated patients had lower Big-ET levels at 3 months than patients receiving placebo (median 9.1 pg/mL versus 10.9 pg/mL, P = .05). A decline in ET-1 was associated with increased risk of the composite endpoint.. Lack of effect of bucindolol on natriuretic peptide levels appears consistent with its overall lack of efficacy in BEST.

Topics: Adrenergic beta-Antagonists; Aged; Atrial Natriuretic Factor; Biomarkers; Endothelin-1; Endothelins; Female; Follow-Up Studies; Heart Failure; Humans; Male; Middle Aged; Natriuretic Peptide, Brain; Propanolamines; Radioimmunoassay; Stroke Volume; Survival Rate; Treatment Outcome