Which medication decreases preload in heart failure?

• A. Diuretic
• B. Angiotensin receptor blocker
• C. Long-acting nitrate
• D. Beta blocker

Answer: (C)

Reducing preload means lowering the amount of blood returning to the heart, which lowers the filling pressures of the ventricles. Long-acting nitrates do this by dilating veins more than arteries, so venous capacitance increases and venous return to the heart decreases. That direct venodilation lowers left ventricular fill pressure and helps relieve congestion in heart failure, which is why they are effective at decreasing preload.

Diuretics also reduce preload, but they do so by reducing overall blood volume rather than by venous dilation. The other medications don’t target preload with the same direct venous-dilation mechanism: ARBs mainly lower afterload, and beta blockers decrease heart rate and contractility without a primary preload-reduction mechanism.