In a 12-year-old male with fever, sore throat, painful joints, annular skin rash, and a heart murmur, which murmur is most likely?

• A. Aortic regurgitation
• B. Tricuspid regurgitation
• C. Mitral regurgitation
• D. Mitral stenosis

Answer: (C)

Fever after a streptococcal throat infection with migratory joint pains and an annular skin rash points to acute rheumatic fever, an autoimmune process that can involve the heart. In the acute phase, the mitral valve is the most commonly affected valve, and inflammation of the valve causes mitral regurgitation. This produces a holosystolic, or pansystolic, murmur best heard at the apex and often radiating to the axilla, reflecting imperfect closure of the mitral valve due to inflammatory damage. Over time, chronic rheumatic involvement can lead to mitral stenosis, but that is a later consequence. So the murmur most likely in this setting is mitral regurgitation.