Effects of carvedilol or metoprolol on PAI-1, tPA-mass concentration or Von Willebrand factor in chronic heart failure - a COMET substudy

NT-proBNP and D-Dimer in acute decompensated heart failure: assessment of diagnostic accuracy and correlation with echocardiographic parameters

PURPOSE

Abnormalities in coagulation and inflammation exist in heart failure. This study compares the diagnostic accuracy of NT-proBNP and D-Dimer and the correlation of these biomarkers with echocardiographic parameters in acute decompensated heart failure.

METHODS

A retrospective cross-sectional/observational study was performed using 162 patients with acute decompensated heart failure and 253 age-matched controls. Patients were ruled out for a pulmonary embolus by CT or VQ scans. The study protocol was approved by Institutional Review Board, Lubbock, TX. Correlation of NT-proBNP and D-Dimer values was done with echocardiographic parameters. Statistical significance was assumed at p < 0.05.

RESULTS

D-Dimer showed a positive correlation with NT-proBNP (r = 0.665, p = 001). The AUC for NT-proBNP, D-Dimer and a combination of D-Dimer plus NT-proBNP were 0.963, 0.928 and 0.982 respectively. The AUC value for D-Dimer versus the combination of D-Dimer and NT-roBNP was not significant (p = 0.21). Correlation of NT-proBNP was significant with the echocardiographic parameters but D-Dimer did not significantly correlate with any of the echocardiographic parameters studied.

CONCLUSIONS

Comparison of the AUC values for D-Dimer versus the combination of D-Dimer and NT-proBNP showed no significance suggestive of comparable diagnostic accuracy in the study population. The lack of correlation between D-Dimer and echocardiographic parameters suggests an independent pathophysiological mechanism underlying upregulation of D-Dimer in acute decompensated heart failure. Further systematic studies are needed to define mechanism of D-Dimer increase in heart failure.

β-blockade abolishes the augmented cardiac tPA release induced by transactivation of heterodimerised bradykinin receptor-2 and β2-adrenergic receptor in vivo

Bradykinin (BK) receptor-2 (B2R) and β2-adrenergic receptor (β2AR) have been shown to form heterodimers in vitro. However, in vivo proofs of the functional effects of B2R-β2AR heterodimerisation are missing. Both BK and adrenergic stimulation are known inducers of tPA release. Our goal was to demonstrate the existence of B2R-β2AR heterodimerisation in myocardium and to define its functional effect on cardiac release of tPA in vivo. We further investigated the effects of a non-selective β-blocker on this receptor interplay. To investigate functional effects of B2R-β2AR heterodimerisation (i. e. BK transactivation of β2AR) in vivo, we induced serial electrical stimulation of cardiac sympathetic nerves (SS) in normal pigs that underwent concomitant BK infusion. Both SS and BK alone induced increases in cardiac tPA release. Importantly, despite B2R desensitisation, simultaneous BK infusion and SS (BK+SS) was characterised by 2.3 ± 0.3-fold enhanced tPA release compared to SS alone. When β-blockade (propranolol) was introduced prior to BK+SS, tPA release was inhibited. A persistent B2R-β2AR heterodimer was confirmed in BK-stimulated and non-stimulated left ventricular myocardium by immunoprecipitation studies and under non-reducing gel conditions. All together, these results strongly suggest BK transactivation of β2AR leading to enhanced β2AR-mediated release of tPA. Importantly, non-selective β-blockade inhibits both SS-induced release of tPA and the functional effects of B2R-β2AR heterodimerisation in vivo, which may have important clinical implications.

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

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 (123)I-meta-iodobenzylguanidine ((123)I-MIBG) imaging when either β-blocker is used. Second, we assessed whether that response correlates with levels of various serum factors that serve as markers for coagulability.

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 the β2-receptor were randomized to equipotent dosages of carvedilol or metoprolol for two 6-wk periods. Primary outcome was sympathetic activity as measured by (123)I-MIBG myocardial washout. Secondary outcomes included markers of hemostasis.

RESULTS

(123)I-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.

CONCLUSION

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.