What are the indications for surgical management of endocarditis?

The indications for surgical management of endocarditis fall into six categories.

1. Congestive heart failure
   Patients with moderate-to-severe heart failure require urgent surgical intervention. With mitral regurgitation, afterload reduction and diuretic therapy can improve symptoms and may make it possible to postpone surgical repair until a full course of antibiotic therapy has been completed. In contrast, acute aortic regurgitation progresses rapidly despite an initial favourable response to medical therapy, and early surgical intervention is imperative.
2. Persistent sepsis
   This is defined as failure to achieve bloodstream sterility after 3–5 days of appropriate antibiotic therapy or a lack of clinical improvement after one week.
3. Recognised virulence of the infecting organism
   
   • With native valve endocarditis, streptococcal infections can be cured with medical therapy in 90%. However, S. aureus and gram negative bacteria are more aggressive, requiring transoesophageal echocardiography to rule out deep tissue invasion or subtle valvular dysfunction. Fungal infections invariably require surgical intervention
   • With prosthetic valve endocarditis, streptococcal tissue valve infections involving only the leaflets can be cleared in 80% with antibiotic therapy alone; however, mechanical or tissue valve infections involving the sewing ring generally require valve replacement. If echocardiography demonstrates a perivalvular leak, annular extension, or a large vegetation, early operation is necessary
4. Extravalvular extension
   Annular abscesses are more common with aortic (25-50%) than mitral (1-5%) infections; in either case, surgical intervention is preferred (survival: 25% medical, 60-80% surgical). Conduction disturbances are a typical manifestation.
5. Peripheral embolisation
   This is common (30-40%), but the incidence falls dramatically following initiation of antibiotic therapy. Medical therapy is appropriate for asymptomatic aortic or small vegetations. Surgical therapy is indicated for recurrent or multiple embolisation, large mobile mitral vegetations or vegetations that increase in size despite appropriate medical therapy.
6. Cerebral embolisation
   Operation within 24 hours of an infarct carries a 50% exacerbation and 67% mortality rate, but the risk falls after two weeks (exacerbation <10%,>