Which medication reduces cardiac workload by lowering heart rate and contractility?

• A. Nitroglycerin
• B. Beta-blocker
• C. Aspirin
• D. Statin

Answer: (B)

Reducing cardiac workload is achieved by lowering myocardial oxygen demand, which largely depends on heart rate and the strength of each contraction. A beta-blocker does exactly that: it blocks beta-adrenergic receptors in the heart, slowing the SA node and reducing the force of contraction. The result is a lower heart rate and weaker contractions, which decrease myocardial oxygen consumption and wall stress. Nitroglycerin mainly lowers workload by dilating veins to reduce preload (and can lower afterload), but it does not directly suppress heart rate or contractility. Aspirin and statins don’t impact heart rate or contractility; they influence clotting and cholesterol, respectively. So the medication that best fits the description is a beta-blocker.