Key result
Prenalterol initially improved left ventricular contractility, but increased systemic vascular resistance after 2 to 18 weeks extinguished the initial clinical improvement.
Why the study?
The initial antifailure efficacy of beta-adrenergic agonists is generally lost during prolonged treatment, but the reasons are not fully understood.
Does prenalterol improve cardiac function and clinical condition in patients with advanced cardiac decompensation due to dilated cardiomyopathy?
Does prenalterol improve cardiac function and clinical condition in patients with advanced cardiac decompensation due to dilated cardiomyopathy?
Prolonged treatment with the beta-1 agonist prenalterol in dilated cardiomyopathy causes systemic vasoconstriction and increased afterload, which overwhelms its initial positive inotropic effects.
Answers are grounded in this paper and cite their sources.
May limit durable benefit from inotropes in HF; leaves open vascular resistance effects on long-term outcomes.
The initial antifailure efficacy of beta-adrenergic agonists is generally lost during prolonged treatment. The reasons are not fully understood. In 11 patients with advanced cardiac decompensation due to dilated cardiomyopathy, prenalterol, a selective beta 1 adrenergic agonist, improved the left ventricular contractility after acute intravenous and during prolonged oral administration. However, after periods of treatment ranging from 2 to 18 weeks, blood pressure and systemic vascular resistance were raised in each patient. These changes resulted in an increase of the left ventricular afterload which was such as to overwhelm the effects of the enhanced contractility, and to extinguish the initial improvement of the cardiac function and of the clinical condition. Stimulation of the presynaptical beta-receptors facilitating norepinephrine release or of the renin secretion by this beta 1 agonist, may be the causes of the systemic vasoconstriction and of the loss of effectiveness in the long run.
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Guazzi et al. (1985) studied Advanced cardiac decompensation due to dilated cardiomyopathy (n=11). Prenalterol was evaluated on Left ventricular contractility, blood pressure, and systemic vascular resistance. Prenalterol initially improved left ventricular contractility, but increased systemic vascular resistance after 2 to 18 weeks extinguished the initial clinical improvement.
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