Do beta-adrenergic blocking agents increase coronary flow reserve?

Abstract

The following conclusions were drawn from this study. Metoprolol is associated with a significant increase in postischemic and pharmacologic CFVR. However, postischemic CFVR is significantly higher than pharmacologic CFVR. The increase in CFVR by metoprolol can be explained by a reduction in vascular resistance. The increase in CFVR (= increased supply) and the reduction in oxygen consumption (= decreased demand) after metoprolol explain the beneficial effect of this beta-blocker in patients with CAD.

Função endotelial vascular em pacientes com fluxo coronário lento e os efeitos do nebivolol

“…This phenomenon has been attributed to the unopposed alpha-adrenergic vasomotor tone. However, selective betablockers like metoprolol have been confirmed to improve myocardial perfusion by increasing coronary flow reserve 30 . Nebivolol, a highly selective beta 1 -adrenergic receptor-blocker with NO-modulating properties, may be especially useful for improving coronary flow reserve due to its vasodilating properties on the small and large coronary arteries 30 .…”

“…However, selective betablockers like metoprolol have been confirmed to improve myocardial perfusion by increasing coronary flow reserve 30 . Nebivolol, a highly selective beta 1 -adrenergic receptor-blocker with NO-modulating properties, may be especially useful for improving coronary flow reserve due to its vasodilating properties on the small and large coronary arteries 30 . The marked vasodilating effect of nebivolol in human coronary microvessels is well established under in vitro conditions 31,32 .…”

Beta-Blockers and Coronary Flow Reserve

“…The beneficial action of carvedilol on CFVR was observed in three reports, including exclusively patients with idiopathic dilated cardiomyopathy, with a therapy time duration ranging between 1 month and 6 months (16)(17)(18). In these experiences, the increase of CFVR was mainly due to the increase of maximal CBF velocity, attributable to diminution of extravascular compressive forces and of LV filling pressure (5,6), to blunted heart rate response beneficially affecting the diastolic myocardial perfusion during hyperemia (6), to alpha-adrenergic blocking action and to improved endothelial function (23,24) possibly producing a better hyperemic microvascular vasodilation.. The studies performed by using nebivolol involved several clinical settings, such as patients with arterial hypertension (7,18,21), idiopathic dilated cardiomyopathy (19) and coronary artery disease (20).…”

“…Both non selective (propranolol) and selective (atenolol) beta-blocking agents have shown a gradual vasoconstriction, i.e., a decrease in coronary artery diameter by approximately 20-25%, over 20 min after their acute administration, an effect which is overcome by nitrates (3). An alternative mechanisms for explaining the reduction of CBF at rest is provided by the reduction of myocardial oxygen demand since these drugs lower blood pressure and heart rate with variable degree (4,5). After acute injection, beta-blockers decrease myocardial contractility and work, leading to a reduction of resting CBF (5).…”

“…An alternative mechanisms for explaining the reduction of CBF at rest is provided by the reduction of myocardial oxygen demand since these drugs lower blood pressure and heart rate with variable degree (4,5). After acute injection, beta-blockers decrease myocardial contractility and work, leading to a reduction of resting CBF (5). The effects of first and second generation beta-blockers on maximal CBF are more controversial.…”