What are the guidelines for intervention in infective endocarditis?

Guidelines for Intervention in Infective Endocarditis

Surgical intervention is mandatory for infective endocarditis with severe acute regurgitation/obstruction causing heart failure, uncontrolled infection, or persistent large vegetations after embolic episodes, and should be performed urgently or emergently depending on the specific indication. 1

Indications for Surgical Intervention

Emergency Surgery (within 24 hours)

• Aortic or mitral native valve endocarditis (NVE) or prosthetic valve endocarditis (PVE) with:
  • Severe acute regurgitation, obstruction, or fistula causing refractory pulmonary edema or cardiogenic shock 1

Urgent Surgery (within a few days)

1. Heart Failure

   • Aortic or mitral NVE or PVE with severe regurgitation or obstruction causing symptoms of heart failure or echocardiographic signs of poor hemodynamic tolerance 1

2. Uncontrolled Infection

   • Locally uncontrolled infection (abscess, false aneurysm, fistula, enlarging vegetation) 1
   • Infection caused by fungi or multiresistant organisms 1
   • Persistent positive blood cultures despite appropriate antibiotic therapy 1
   • PVE caused by staphylococci or non-HACEK gram-negative bacteria 1

3. Prevention of Embolism

   • Aortic or mitral NVE or PVE with persistent vegetations >10 mm after one or more embolic episodes despite appropriate antibiotic therapy 1
   • Aortic or mitral NVE with vegetations >10 mm, associated with severe valve stenosis or regurgitation, and low operative risk 1
   • Aortic or mitral NVE or PVE with isolated very large vegetations (>30 mm) 1

Right-Sided Endocarditis Surgical Indications

For right-sided native valve IE in intravenous drug users, surgery should be considered when:

• Microorganisms are difficult to eradicate (e.g., persistent fungi) or bacteremia for >7 days (e.g., S. aureus, P. aeruginosa) despite adequate antimicrobial therapy 1
• Persistent tricuspid valve vegetations >20 mm after recurrent pulmonary emboli with or without concomitant right heart failure 1
• Right heart failure secondary to severe tricuspid regurgitation with poor response to diuretic therapy 1

Antimicrobial Therapy Guidelines

Empiric Treatment

Initial empiric treatment should cover staphylococci, streptococci, and enterococci until the causative organism is identified 1, 2:

1. Native Valve or Late Prosthetic Valve Endocarditis:

   • Ampicillin 12 g/day IV in 4-6 doses PLUS
   • (Flu)cloxacillin or oxacillin 12 g/day IV in 4-6 doses PLUS
   • Gentamicin 3 mg/kg/day IV or IM in 1 dose 2

2. Early Prosthetic Valve or Healthcare-Associated Endocarditis:

   • Vancomycin 30 mg/kg/day IV in 2 doses PLUS
   • Gentamicin 3 mg/kg/day IV or IM in 1 dose PLUS
   • Rifampin 900-1200 mg IV or orally in 2-3 divided doses 2

3. Penicillin-Allergic Patients:

   • Vancomycin 30-60 mg/kg/day IV in 2-3 doses PLUS
   • Gentamicin 3 mg/kg/day IV or IM in 1 dose 2

Duration of Therapy

• Native valve endocarditis: 4 weeks for most cases 2
• Prosthetic valve endocarditis: 6 weeks 2
• Right-sided IE due to MSSA: 2-week treatment with oxacillin (or cloxacillin) without gentamicin may be sufficient if all these criteria are met:
  • Good response to treatment
  • Absence of metastatic sites of infection or empyema
  • Absence of cardiac and extracardiac complications 1

Diagnostic Approach and Monitoring

Initial Evaluation

• Transthoracic echocardiography (TTE) is recommended as first-line imaging for all suspected IE cases 1
• Transesophageal echocardiography (TOE) is recommended when:
  • TTE is negative or non-diagnostic but clinical suspicion remains high
  • Prosthetic heart valve or intracardiac device is present 1

Follow-up During Treatment

• Repeat echocardiography within 5-7 days if initial examination is negative but clinical suspicion remains high 1
• Repeat echocardiography as soon as a new complication is suspected (new murmur, embolism, persistent fever, heart failure, abscess, atrioventricular block) 1
• Intraoperative echocardiography is recommended in all cases of IE requiring surgery 1
• Monitor renal function and drug levels for certain antibiotics (aminoglycosides, vancomycin) 2

Outpatient Parenteral Antibiotic Therapy (OPAT)

OPAT may be considered after the critical phase (first 2 weeks) if:

• Patient is medically stable
• No complications (heart failure, concerning echocardiographic features, neurological signs, renal impairment)
• Patient education and regular follow-up are established 1

Common Pitfalls and Caveats

1. Diagnostic Delays:

   • Failure to obtain adequate blood cultures before starting antibiotics
   • Not repeating echocardiography when clinical suspicion remains high despite initial negative results

2. Treatment Errors:

   • Inadequate empiric coverage
   • Premature narrowing of antibiotic spectrum
   • Inadequate duration of therapy
   • Delayed surgical evaluation in cases meeting surgical criteria

3. Monitoring Issues:

   • Failure to monitor for complications during treatment
   • Inadequate follow-up after completion of therapy

4. Special Populations:

   • Right-sided endocarditis in intravenous drug users may be treated with shorter courses of antibiotics if specific criteria are met
   • Prosthetic valve endocarditis requires longer treatment duration and often combination therapy

5. Neurological Complications:

   • After a silent embolism or transient ischemic attack, cardiac surgery, if indicated, should proceed without delay
   • Following intracranial hemorrhage, surgery should generally be postponed for ≥1 month 1

Remember that early multidisciplinary collaboration between infectious disease specialists, cardiologists, and cardiac surgeons is essential for optimal management of infective endocarditis.