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Right-Sided Endocarditis IVDU — SCE Infectious Diseases MCQ

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ModerateBone & Joint InfectionRight-Sided Endocarditis IVDUSCE Infectious Diseases

A 35-year-old man develops infective endocarditis 3 months after IV drug injection. TOE shows a 22 mm tricuspid valve vegetation with moderate tricuspid regurgitation. Blood cultures grow MSSA. He responds well to IV Flucloxacillin. What is unique about the prognosis and surgical approach for right-sided endocarditis?

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Correct answer: C — Right-sided IE (tricuspid) in IVDU has better prognosis than left-sided IE; surgery is rarely needed; large vegetation size alone is not a surgical indication; 4 weeks of IV antibiotics is often curative

Right-sided infective endocarditis (predominantly tricuspid valve in IVDU) has a significantly better prognosis than left-sided IE (~3–5% mortality vs 20–30%). This is because the pulmonary vasculature tolerates septic emboli better than the systemic circulation. Large tricuspid vegetations (even >20 mm) alone are NOT an indication for surgery (unlike left-sided IE). Surgery is reserved for: failure of antibiotic therapy (persistent bacteraemia >7 days despite appropriate therapy), fungal endocarditis, or recurrent septic pulmonary emboli with respiratory failure. Standard treatment is 4–6 weeks of IV anti-staphylococcal antibiotics.

Reference: ESC 2023 – Endocarditis; BSAC 2012 – Right-sided IE in IVDU