• Consider in patients with known risk factors and unexplained fever
  • Mitral valve most commonly affected overall; tricuspid valve most common in IVDA
  • Noninfectious vegetations can arise in patients with malignancy/SLE/Hypercoagulable state ("Marantic" endocarditis)
  • S. aureus is single most common cause
  • Strep viridans is the most common cause of native valve endocarditis, excluding risk factors below
  • Blood cultures are falsely negative ~5% (think HACEK organisms)
  • Only 20% have an increase in a known murmur and only 48% have a new murmur[1]


  • No longer recommended at all in the United Kingdom[2]
  • In United States, only recommended for invasive dental procedures (not routine cleanings) and invasive respiratory procedures in setting of: [3][4]
  1. Prosthetic valves
  2. Prior endocarditis
  3. Un-repaired congenital cyanotic heart disease
  4. Repaired congenital heart disease/valvulopathy with prosthetic material

Risk Factors

  • IVDA
    • Tricuspid valve most commonly affected
  • Prosthetic heart valve
    • Coagulase negative staphylcocci are substantial etiologies in this patient population[5]
  • Structural heart disease
    • Rheumatic heart disease
    • Mitral valve prolapse
    • Bicuspid aortic valve
  • Hemodialysis
  • HIV infection
  • Fungal endocarditis risk factors, with Candida most common
    • Prolonged antibiotics
    • TPN through central line

Clinical Features

  • Fever
    • Present in 80% of cases
  • Heart murmur
    • Preexisting murmur found in 85% of cases; new murmur found in 48%
  • CHF
    • Acute or progressive (70%)
  • Embolic manifestations
    • Major arterial emboli
    • Septic pulmonary infarction
    • Janeway lesions
  • CNS
  • Pulmonary
  • Cardiac
  • Abdominal
    • Bowel, renal, splenic infarcts
  • Derm
    • Osler nodes - tender red/purple nodules on distal finger and toes
    • Splinter hemorrhages - nail bed hemorrhages not extending the length of the nail
  • (Janeway lesions - painless macules on palms and soles due to microabscesses

Differential Diagnosis






  • Blood culture (from 3 separate sites)[7]
  • CBC
  • Urinalysis
  • ESR
    • Elevated in >90% of cases
  • ECG
    • Ischemia, heart block
  • CXR
    • Pulmonary emboli, CHF
  • Ultrasound
    • Obtain as soon as possible
    • TEE may be required for:
      • Prosthetic valves
      • Difficulty obtaining clear TTE images (obesity, COPD)
      • High clinical probability of endocarditis

Evaluation Notes

  • Inpatient diagnosis is based on the Duke's Criteria although many of the criteria are not filled in the ED
    • Heightened clinical suspicion is necessary even if diagnosis does not meet the official criteria.[8]

Modified Duke Criteria[9]

  • 2 major criteria OR
  • 1 major and 3 minor criteria OR
  • 5 minor criteria

Major Criteria

  • Positive blood culture with typical IE microorganism, defined as one of the following:
    • Typical microorganism consistent with IE from 2 separate blood cultures, as noted below:
    • Microorganisms consistent with IE from persistently positive blood cultures defined as:
      • Two positive cultures of blood samples drawn >12 hours apart, or
      • All of 3 or a majority of 4 separate cultures of blood (with first and last sample drawn 1 hour apart)
      • Coxiella burnetii detected by one positive blood culture or IgG
      • Staphylococus lugdunensis should raise concerns for endocarditis with a single positive blood culture[10]
  • Evidence of endocardial involvement with positive echocardiogram defined as:
    • Valvular mass or supporting structures or
    • Abscess, or
    • New disruption of a prosthetic valve or new valvular regurgitation

Minor Criteria

  • Predisposing factor: known cardiac lesion, recreational drug injection
  • Fever >38°C
  • Evidence of emboli: arterial emboli,pulmonary infarcts, Janeway lesions, conjunctival hemorrhage
  • Glomerulonephritis, Osler's nodes
  • Positive blood culture (that does not meet a major criterion) or serologic evidence of infection


Initial management should focus on early blood cultures and antibiotics

CHF/Cardiogenic Shock

  • Often due to valve failure, rupture, or a new defect.

Pulmonary edema

  • Often due to mitral or aortic valve rupture causing severe regurgitation
  • Focus on after-load reduction

Respiratory failure (emboli)

  • Often requires intubation with failure either due to CHF or Pneumonia
  • Multi-lobar pneumonia suggests a tricuspid or pulmonary valve lesion with emboli to lungs


Start after 3 sets of blood cultures are obtained (if possible)[7]

Therapy should be based on:

  • Whether the patient has received prior antibiotic therapy
  • Prosthetic valves
  • Local antibiotic resistance patterns or knowledge of prior endocarditis cultures
  • Prior hospitalizations and risk of MRSA

Native Valves


Suspected MRSA:[11]

Prosthetic Valves (Early)

Early prosthetic valve endocarditis defined as < 12 months post surgery[11]

IV Drug User without Prosthetic Valve

Prosthetic Valve (Late)

Late prosthetic valve endocarditis defined as ≥ 12 months post surgery[11]
  • Same as native valve endocarditis empiric therapy

Dental Procedure Prophylaxis

All antibiotics options are given as a single dose 1 hour prior to the dental procedure



Admit all suspected cases and consult Cardiothoracic surgery for endocarditis complicated by:[1]

  • New Heart failure suspected due to severe regurgitation
  • Cardiogenic Shock
  • Echocardiography demonstrating a new fistula
  • Surgery indicated for[13]:
    • Acute heart failure
    • Periannular extension
    • Recurrent emboli
    • Large mobile vegetations
    • Persistent bacteremia
    • Fungal endocarditis (penetration of antifungals into vegetation walls poor)[14]


  • No therapeutic anticoagulation necessary
    • Anticoagulation carries higher risk of bleeding without delivering mortality benefit or reducing embolic complication[15]
  • Septic pulmonary embolism
    • Most common culture growths are MSSA, MRSA, and candida[16]
    • Furthermore, therapeutic anticoagulation not indicated for septic pulmonary embolism



  • Heart Failure
    • Most common cause of death due to IE
  • Perivalvular Abscess


  • CVA
  • Blindness
  • Painful, ischemic extremities
  • Unusual pain syndromes (due to splenic or renal infarction)
  • Mycotic aneurysm
  • Hypoxia
  • MI





  1. Hoen, B. et al. Infective Endocarditis. NEJM. 2013. 368;15. 1425-1433 PDF
  2. Wilson W. et al. Prevention of infective endocarditis: guidelines from the American Heart Association: a guideline from the American Heart Association Rheumatic Fever, Endocarditis, and Kawasaki Disease Committee, Council on Cardiovascular Disease in the Young, and the Council on Clinical Cardiology, Council on Cardiovascular Surgery and Anesthesia, and the Quality of Care and Outcomes Research Interdisciplinary Working Group. Circulation 2007;116(15):e376-e377.
  3. Richey R, Wray D, Stokes T. Prophylaxis against infective endocarditis: summary of NICE guidance. BMJ 2008;336: 770-1.
  4. Wilson W, et al. Prevention of Infective Endocarditis: Guidelines from the American Heart Association. Circulation. 2007;116:1736-1754
  5. Lalani T et al. Prosthetic valve endocarditis due to coagulase-negative staphylococci: findings from the International Collaboration on Endocarditis Merged Database. Eur J Clin Microbiol Infect Dis. 2006 Jun;25(6):365-8.
  6. Mylonakis. E, Calderwood S. Infective endocardidits in adults. NEJM. 2001;345(18):138-1330
  7. Lee A, Mirrett S, Reller LB, Weinstein MP. Detection of bloodstream infections in adults: how many blood cultures are needed? J Clin Microbiol 2007;45: 3546 – 3548
  8. Durack D, Lukes A, Bright D "New criteria for diagnosis of infective endocarditis: utilization of specific echocardiographic findings. Duke Endocarditis Service". Am J Med. 1994. 96 (3): 200–9
  9. Li, JS et al. "Proposed Modifications to the Duke Criteria for the Diagnosis of Infective Endocarditis". Clinical Infectious Diseases. 2000. 30(4). 633.
  10. Liu Po-Yen et al. Staphylococcus lugdunensis Infective Endocarditis: A Literature Review and Analysis of Risk Factors. Journal of Microbiology, Immunology and Infection Volume 43, Issue 6, December 2010, Pages 478-484.
  11. ESC Task Force Guidelines on the prevention, diagnosis, and treatment of infective endocarditis. European Heart Journal (2009) 30, 2369–2413 doi:10.1093/eurheartj/ehp285 PDF
  12. AHA Pocket Card Dental Prophylaxis Endocarditis
  13. Kosowsky JM, Takhar SS: Infective Endocarditis and Valvular Heart Disease in Marx JA, Hockberger RS, Walls RM, et al (eds): Rosen’s Emergency Medicine: Concepts and Clinical Practice, ed 8. St. Louis, Mosby, Inc., 2013, (Ch) 84: pp 1113-1123.
  14. British Society for Antimicrobial Chemotherapy. Guidelines for the antibiotic treatment of endocarditis in adults: report of the Working Party of the British Society for Antimicrobial Chemotherapy. J. Antimicrob. Chemother. (December 2004) 54 (6): 971-981.
  15. Elkaryoni A et al. ANTICOAGULATION IN INFECTIVE ENDOCARDITIS: INSIGHTS FROM NATIONWIDE INPATIENT SAMPLE. Journal of the American College of Cardiology. Volume 73, Issue 9 Supplement 1, March 2019.
  16. Li Zhao RY et al. Clinical characteristics of septic pulmonary embolism in adults: A systematic review. Respiratory Medicine. Volume 108, Issue 1, January 2014, Pages 1-8.
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