Urgent

• Hypotension or pulmonary oedema
• Clinically severe aortic or mitral regurgitation (rapid deterioration may occur)
• Suspicion of an abscess (ill patient, long PR interval, S. aureus bacteraemia)

• Positive blood culture with organism typically associated with endocarditis, for example viridans group streptococci, Streptococcus bovis group, community-acquired S. aureus or enterococci
• IV drug use
• Prosthetic heart valve
• Central venous catheter-related blood-steam infection persisting for >72h after antimicrobial therapy
• New regurgitant murmur (endocarditis rarely causes new obstruction)

Low clinical suspicion of endocarditis (e.g. fever with ejection systolic flow murmur) (see Table 50.6)