Differential effects of nonselective versus selective {beta}-blockers on cardiac sympathetic activity and hemostasis in patients with heart failure

The Journal of Nuclear Medicine, 10/10/2013

De Peuter OR et al. - Carvedilol, a nonselective β-blocker, may be more effective than the selective β-blocker metoprolol in reducing the risk of thromboembolic events in heart failure. The aim of this study was, first, to assess whether there is a differential response in cardiac sympathetic activity by 123I-meta-iodobenzylguanidine (123I-MIBG) imaging when either β-blocker is used. Compared with metoprolol, carvedilol resulted in greater reduction of sympathetic activity after 6 wk of treatment and lower von Willebrand factor concentrations in both Arg16/Gln27 and Gly16/Glu27 individuals. Therefore, carvedilol may reduce the risk of thromboembolic events in patients with heart failure, irrespective of β2-receptor haplotype status.

Methods

  • In this prospective, randomized, open-label crossover study with masked outcome assessments, stable heart failure patients (left ventricular ejection fraction < 40%) homozygous for the Arg16/Gln27 (n = 13) or Gly16/Glu27 haplotype (n = 8) of theβ2-receptor were randomized to equipotent dosages of carvedilol or metoprolol for two 6-wk periods.
  • Primary outcome was sympathetic activity as measured by 123I-MIBG myocardial washout.
  • Secondary outcomes included markers of hemostasis.

Results

  • 123I-MIBG cardiac washout was lower during carvedilol than metoprolol treatment (12.9% ± 3.9% vs. 22.1% ± 2.8%, respectively, P = 0.003), irrespective of β2-adrenergic receptor haplotype.
  • In addition, treatment with carvedilol resulted in a lower von Willebrand factor than did metoprolol (149% ± 13% vs. 157% ± 13%, respectively, P = 0.01), irrespective of β2-adrenergic receptor haplotype.

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