Infective Endocarditis Guidelines

Updated: Aug 07, 2023
  • Author: John L Brusch, MD, FACP; Chief Editor: Michael Stuart Bronze, MD  more...
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Guidelines Summary

Key points of the American Heart Association's guidelines for the treatment of IE in adults are summarized below. [103]


The diagnosis of IE should be based on syndromic reasoning and includes pathologic criteria and clinical criteria. The diagnosis is differentiated as definite, possible, or rejected IE.

Blood cultures

Blood cultures should be collected at least 3 times from different venipuncture sites. The first and second collections should be taken at least 1 hour apart.


Transthoracic echocardiography (TTE) should be performed as quickly as possible in all cases of suspected IE. If the initial TTE images are inadequate, or if findings are negative in the setting of persistent suspicion for IE, transesophageal echocardiography (TEE) should be performed. Transesophageal echocardiography also should be performed in patients with possible intracardiac complications in whom TTE findings were initially positive. If the suspicion for IE remains high despite negative TEE findings, a repeat TEE should be performed after 3 to 5 days. Furthermore, repeat TEE should be performed if a new intracardiac complication is suggested by clinical features. Performance of TTE also is reasonable upon completion of antibiotic therapy for the establishment of a new baseline.

Surgical intervention

Especially in challenging cases, as below, in which surgery is considered, the therapeutic approach should be arrived at by a team consisting of infectious disease specialist, cardiologist, and cardiac surgeon. In cases of opioid use disorder (OUD), there should be input of a substance abuse specialist and medical ethicist because of the high rate of recidivism in this group of patients. 

The following features may merit surgical intervention:

  • Persistent vegetation following systemic embolization
  • Anterior mitral leaflet vegetation, especially larger than 10 mm
  • One or more embolic events during the first 14 days of antimicrobial therapy
  • Growing vegetation despite appropriate antimicrobial therapy
  • Acute mitral or aortic regurgitation with signs of heart failure
  • Heart failure that does not respond to medical therapy
  • Paravalvular extension
  • Valvular dehiscence, rupture, or fistula formation
  • New heart block
  • Large abscess or extension of abscess despite appropriate antimicrobial therapy

Antimicrobial therapy

The guidelines make specific recommendations for the following:

  • Native valve IE caused by highly susceptible (MIC ≤0.12 µg/mL) viridans group streptococci (VGS)
  • Viridans group streptococci and  S bovis with MIC >0.12 µg/mL to < 0.5 µg/mL
  • Abiotrophia defectiva and  Granulicatella species, and VGS with penicillin MIC ≥0.5 µg/mL
  • Viridans group streptococci or  S bovis infection of prosthetic material
  • Staphylococcal infection
  • Staphylococcal infection of prosthetic material
  • Enterococcal infection
  • Infection with HACEK micro-organisms
  • Infection with non-HACEK gram-negative bacilli
  • Culture-negative endocarditis
  • Fungal infection
  • Early surgery for native valve IE

The following scenarios support early valve surgery for native left-sided IE:

  • Signs or symptoms of heart failure as a result of valve dysfunction
  • IE caused by fungal infection or highly resistant organisms
  • IE complicated by annular abscess, heart block, or destructive perforating lesions
  • Persistent infection (bacteremia or fever; >5-7 days) after appropriate antimicrobial therapy has been initiated, if other sources of fever or infection have been ruled out
  • Recurrent emboli or persistent/growing vegetations despite appropriate antimicrobial therapy

Early surgery (prosthetic valve IE)

The following scenarios support the consideration of early valve surgery for prosthetic valve IE:

  • Signs or symptoms of heart failure resulting from intracardiac fistula, valve dehiscence, or severe prosthetic dysfunction
  • Persistent bacteremia (>5-7 days) after the start of appropriate antimicrobial therapy
  • Prosthetic valve IE complicated by annular abscess, heart block, or destructive perforating lesions
  • Prosthetic valve IE caused by fungal infection or highly resistant organisms
  • Recurrent emboli despite appropriate antimicrobial therapy


It is reasonable to discontinue all forms of anticoagulation for 2 weeks in patients with a mechanical valve and IE in whom a CNS embolic event has occurred. Antiplatelet therapy should not be initiated as adjunctive therapy upon a diagnosis of IE, although established antiplatelet therapy may be continued in patients with IE who have no bleeding complications.

CNS imaging

CNS imaging should be performed to evaluate for CNS bleeding or intracranial mycotic aneurysm in patients with IE with neurological deficits, severe localized headache, or meningeal signs.