Atrial fibrillation affects BNP/NT-proBNP interpretation by doing what?

• A. Increases BNP levels.
• B. Decreases BNP levels.
• C. Has no effect on BNP.
• D. Makes BNP completely unreliable.

Answer: (A)

Atrial fibrillation raises BNP/NT-proBNP levels because the irregular, often rapid rhythm increases atrial and ventricular wall stress. BNP is released by cardiac myocytes in response to stretch, so the heightened filling pressures and tachycardia seen in AF push BNP up even if there isn’t overt heart failure. That’s why BNP interpretation in someone with AF can be higher than expected and may overestimate HF severity unless rhythm and rate are considered. After rate or rhythm control, BNP levels may decline if the stress from AF is reduced, underscoring that the elevation was at least partly due to the rhythm. The other options aren’t accurate: AF doesn’t typically decrease BNP, it does affect BNP, and it doesn’t render BNP completely unreliable—just interpretive context, especially rhythm status, is needed.