Which condition is classically associated with a high ejection fraction due to high-output states such as arteriovenous shunts?

• A. Dilated cardiomyopathy
• B. Severe aortic stenosis
• C. Paget disease of bone with AV shunt
• D. Ischemic heart disease

Answer: (C)

High ejection fraction in a high-output state happens when the circulation is hyperdynamic due to an excess of blood flow demand or low vascular resistance, so the heart pumps a larger volume but contractility remains intact. Paget disease of bone can involve large arteriovenous shunts within bone, creating substantial low-resistance pathways that markedly increase venous return and overall cardiac output. Because the heart is responding to this increased demand with preserved or even elevated contractile function, the ejection fraction stays high despite the high-output load.

The other conditions don’t fit this pattern. Dilated cardiomyopathy damages the heart muscle and lowers systolic function, reducing the ejection fraction. Ischemic heart disease similarly impairs pump function and often decreases EF. Severe aortic stenosis increases afterload and can blunt stroke work, and EF is not characteristically elevated due to a high-output mechanism.