β1-Adrenoceptor Reactivity of Human Myocardium in Coronary Artery Disease with Preserved and Reduced Left-Ventricular Ejection Fraction and Its Relationship with Structural and Functional Parameters of Heart

The relationship between adrenergic reactivity of isolated myocardium of the human right atrial appendage with echocardiography (Echo) parameters was studied in coronary artery disease (CAD) with preserved and reduced ejection fraction (EF) of the left ventricle (LV) upon stimulation of β₁-adrenergic receptors (β₁-AR). Positive dynamics at 20-min observation was shown for the adrenergic reactivity in patients with preserved LVEF, assessed by changes in the contractile force of isolated myocardial strips in response to the stimulation of β₁-AR. As for reduced LVEF, adrenergic reactivity in response to β₁-AR stimulation was poor and had no positive dynamics. Myocardial adrenergic reactivity associated with β₁-AR was a significant factor in determining intracardiac hemodynamics in patients with CAD. This was manifested in the presence of correlations between the mechanical response of isolated myocardium upon stimulation of β₁-AR and the results of Echo. Those correlations had different directions in patients with preserved and reduced EF. The discovered differences in the correlation of cardiac ultrasound parameters with the inotropic response of isolated myocardial fragments upon stimulation of β₁-AR with preserved and reduced EF probably reflected the different severity of heart chamber remodeling and the state of general neurohumoral regulation in the conditions of studied disease.