Which statement about acute MR is true?

• A. It can cause left atrial pressure overload
• B. It commonly presents with chest pain
• C. It never involves papillary muscle rupture
• D. It always has a normal LV size

Answer: (A)

Acute mitral regurgitation causes a rapid rise in left atrial pressure because during systole a regurgitant jet is shunted into the left atrium before it has time to adapt with dilation and improved compliance. That sudden pressure overload in the left atrium leads to pulmonary congestion and edema, which is why this statement is true. Chest pain is not a defining feature of acute MR, though MR can occur in the setting of myocardial infarction. Papillary muscle rupture can cause acute MR, so saying it never involves papillary rupture is incorrect. The left ventricle is not guaranteed to be normal in size—acute MR can present with a normal LV size early, but this is not universally the case, so it’s not accurate to state it always remains normal.