Which beta1 agonist is used for short-term treatment of heart failure?

Which beta1 agonist is used for short-term treatment of heart failure?

• A. Isoproterenol
• B. Norepinephrine
• C. Dobutamine
• D. Pralidoxime

Answer: (C)

Stimulation of beta1 receptors in the heart raises contractility by enhancing calcium dynamics inside cardiac cells, which increases the amount of blood the heart can eject with each beat (positive inotropy) and, to a lesser extent, can affect heart rate. For short-term treatment of heart failure, you want a drug that boosts the heart’s squeezing power without causing significant vasoconstriction or excessive tachycardia. Dobutamine fits this profile as a predominantly beta1 agonist with minimal alpha effects, so it increases contractility and stroke volume with only modest changes in heart rate and afterload, improving cardiac output in acute decompensation.

Isoproterenol, a nonselective beta agonist, can cause marked tachycardia and beta2-mediated vasodilation, which may worsen hemodynamics in heart failure. Norepinephrine has strong alpha-1–mediated vasoconstriction that raises afterload, which can reduce cardiac output despite some beta1 activity. Pralidoxime is an antidote for organophosphate poisoning and has no role in treating heart failure.