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Systemic and coronary hemodynamic effects of beta-adrenoceptor blocking agents in coronary artery disease
1Cardiovascular Diagnostic Laboratory Center, Toho University School of Medicine, Tokyo, Japan.
Insights
Acebutolol, a cardioselective beta-blocker, reduced heart rate and myocardial oxygen demand in patients with coronary artery disease. Unlike propranolol, it showed minimal negative inotropic effects, suggesting efficacy in managing myocardial ischemia.
Area of Science:
- Cardiology
- Pharmacology
Background:
- Coronary artery disease (CAD) poses significant risks, often involving myocardial ischemia during exertion.
- Beta-blockers are crucial in managing CAD, but their effects vary based on selectivity.
Purpose of the Study:
- To investigate the systemic and coronary hemodynamic effects of acebutolol, a cardioselective beta-blocker, in patients with CAD.
- To compare acebutolol's effects with those of propranolol, a non-cardioselective beta-blocker.
Main Methods:
- Simultaneous left and right heart catheterization in 11 CAD patients receiving intravenous acebutolol (10 mg).
- Coronary sinus thermodilution catheterization to assess coronary sinus flow (CSF) and myocardial oxygen consumption (MVO2).
- Comparison with data from 7 patients receiving intravenous propranolol (2 mg).
Main Results:
- Acebutolol significantly reduced heart rate and myocardial oxygen demand (CSF and MVO2) with minimal impact on left ventricular contractility.
- Propranolol also reduced heart rate but significantly increased pulmonary wedge pressure and decreased contractility indicators.
- Acebutolol demonstrated a predominant negative chronotropic effect with less negative inotropic action compared to propranolol.
Conclusions:
- Acebutolol's efficacy in managing myocardial ischemia in CAD may stem from improving the myocardial oxygen demand-supply balance.
- The cardioselective profile of acebutolol offers a hemodynamic advantage over non-cardioselective beta-blockers in this patient population.
Abstract:
Systemic and coronary hemodynamic effects of acebutolol (10 mg i.v.), a cardioselective beta-adrenoceptor blocking agent were investigated in 11 patients with coronary artery disease and significant arterial obstructive lesions. Efficacy was assessed by simultaneous left and right heart catheterization and with an inlaying Webster thermodilution catheter in the coronary sinus. The data were compared with data from 7 other patients who received 2 mg i.v. of propranolol, a non-cardioselective beta-blocker. With acebutolol, (1) the heart rate was reduced significantly (p less than 0.001), (2) no significant changes were observed in the LVSP, LVEDP, mean PWP, LVmax dp/dt/p, LV negative dp/dt/p, CI, SWI and SPI, (3) CSF and MVO2 decreased significantly (p less than 0.01) 5 min after injection and (4) the CVR showed a significant elevation (p less than 0.05) after 5 min. With propranolol, (1) the heart rate decreased significantly (p less than 0.05), (2) there were no significant changes in LVSP and LVEDP, (3) the mean PWP increased significantly (p less than 0.05), (4) the LVmax dp/dt/p, CI and SWI decreased significantly (p less than 0.05), (5) the CSF and MVO2 decreased markedly (p less than 0.01) and (6) the CVR increased markedly (p less than 0.01). As compared to the effects of 2 mg i.v. of propranolol, those produced by acebutolol (10 mg i.v.) were characterized by a predominant negative chronotropic action with minimal negative inotropic action, combined with a reduction in CSF and MVO2. The findings suggest that the efficacy of acebutolol in pump failure caused by myocardial ischemia during effort angina is mediated by improvement of the myocardial oxygen demand-supply imbalance.