What are the signs of infective endocarditis?

Signs of Infective Endocarditis

Fever is the most frequent sign of infective endocarditis, present in up to 90% of patients, and should prompt consideration of IE when accompanied by other risk factors or clinical findings. 1

Cardinal Clinical Manifestations

Systemic Signs and Symptoms

• Fever: Present in up to 90% of patients, often with systemic symptoms including chills, poor appetite, and weight loss 1
  • Note: Fever may be absent in elderly patients, after antibiotic pre-treatment, in immunocompromised patients, or with less virulent organisms 1
• Heart murmurs: Present in approximately 85% of patients 1
• Constitutional symptoms: Fatigue, night sweats, and malaise

Cardiac Manifestations

• New regurgitant heart murmur: A key finding that should immediately raise suspicion for IE 1
• Worsening of pre-existing murmur
• Evidence of congestive heart failure: Due to valvular dysfunction 1
• New conduction disturbances: Particularly atrioventricular blocks, which may indicate perivalvular extension of infection 1

Vascular and Immunological Phenomena

• Vascular phenomena:

  • Major arterial emboli (stroke, limb ischemia)
  • Septic pulmonary infarcts (in right-sided IE)
  • Mycotic aneurysms
  • Intracranial hemorrhages
  • Conjunctival hemorrhages
  • Janeway lesions (painless, hemorrhagic macules on palms and soles)

• Immunological phenomena:

  • Glomerulonephritis
  • Osler's nodes (painful, raised lesions on fingers or toes)
  • Roth spots (retinal hemorrhages with pale centers)
  • Rheumatoid factor positivity 1

Embolic Events

• Cerebral emboli: Presenting as stroke or transient ischemic attack
• Pulmonary emboli: Common in right-sided IE
• Peripheral emboli: Affecting spleen, kidneys, limbs
• Peripheral abscesses: In organs such as kidney, spleen, brain, or vertebrae 1

High-Risk Scenarios for IE

IE should be strongly suspected in the following situations:

1. Fever in patients with:

   • Intracardiac prosthetic material (prosthetic valves, pacemakers, implantable defibrillators)
   • Previous history of IE
   • Known valvular or congenital heart disease
   • Immunocompromised state or injection drug use
   • Recent intervention with associated bacteremia 1

2. Unexplained embolic events of unknown origin

3. Sepsis of unknown origin, especially if associated with typical IE-causing organisms 1

Diagnostic Approach

When IE is suspected, the following diagnostic steps are essential:

1. Blood cultures: Obtain at least 3 sets from separate venipuncture sites before starting antibiotics 2

   • Positive blood cultures with typical IE organisms (Staphylococcus aureus, viridans streptococci, HACEK group) strongly support the diagnosis 1

2. Echocardiography:

   • Transthoracic echocardiography (TTE) is the first-line imaging modality
   • Transesophageal echocardiography (TEE) should be performed if TTE is negative but clinical suspicion remains high 2
   • Echocardiographic findings supporting IE include:
     • Vegetation
     • Abscess
     • New partial dehiscence of prosthetic valve
     • New valvular regurgitation 1

Pitfalls and Caveats

1. Atypical presentations:

   • Elderly patients may present without fever
   • Right-sided IE may lack peripheral vascular phenomena
   • Previous antibiotic therapy may mask typical features 1

2. Diagnostic delays:

   • Subacute presentations with non-specific symptoms can delay diagnosis
   • Consider IE in any patient with unexplained fever and risk factors 1

3. Culture-negative endocarditis:

   • May occur in up to 20% of cases, often due to prior antibiotic administration
   • Special culture techniques or molecular methods may be needed for diagnosis 1

4. Prosthetic valve endocarditis:

   • May have more subtle findings
   • Always requires TEE for adequate evaluation 2

Early recognition of these signs and prompt diagnostic evaluation are crucial for improving outcomes in infective endocarditis, as mortality remains high despite advances in treatment.