Abstract 3139: Beta Adrenoceptor Polymorphisms are Associated with Differential Hemodynamic Responses During Dobutamine Stress Echocardiography
Introduction: Single nucleotide polymorphisms (SNPs) of the beta adrenoceptors have been associated with different responses to catecholamines in healthy volunteers. We aimed to explore the association between these SNPs and the hemodynamic response to dobutamine in patients referred for dobutamine stress echocardiography (DSE).
Methods: Consecutive patients referred for DSE at the UCSF Adult Echocardiography Laboratory received incremental dobutamine infusions of 5, 10, 20, 30, and 40 mcg/kg/min. The heart rate (HR) and systolic blood pressure (SBP) were recorded at each stage and the protocol was stopped when target HR (85% of maximal age predicted HR) was achieved or symptoms developed. The predictor variables for the analysis were the genotypes of two beta-1 (B1AR: Ser49Gly, Arg389Gly) and two beta-2 (B2AR: Gly16Arg, Gln27Glu) SNPs. The outcome variables were the change in SBP and achievement of target HR. The associations between predictor and outcome variables were quantified by multivariate regression (adjusting for sex, race, and baseline HR/SBP), reporting odds ratios (OR), coefficients (coef) and 95% confidence intervals (CI).
Results: The study included 47 subjects. B1AR Gly49 homozygotes/heterozygotes were more likely to reach target HR than Ser49 homozygotes (OR 5.8/CI 1.2–28.0/P=0.029). B2AR Glu27 homozygotes/heterozygotes had higher SBPs than Gln27 homozygotes at the 10 and 20 mcg/kg/min dobutamine doses (coef 20 mmHg/CI 8–33/P=0.002 and 26 mmHg/CI 3– 49/P=0.026, respectively). B2AR Gly16 homozygotes/heterozygotes had higher SBPs than Arg16 homozygotes at 20 mcg/kg/min (coef 32 mmHg, CI 7–57, P=0.014). Smaller sample sizes at the higher dobutamine doses limited the statistical power of those analyses.
Conclusion: Beta adrenoceptor SNPs are associated with differential heart rate and blood pressure responses in patients referred for DSE. Genetic variation may impact the sensitivity of DSE by modulating the ability to achieve target heart rate and may partially explain the observed variability in blood pressure response during DSE.