What are the clinical features of Infective Endocarditis (IE)?

Clinical Features of Infective Endocarditis (IE)

Infective endocarditis presents with diverse clinical manifestations ranging from acute, rapidly progressive infection to subacute or chronic disease with non-specific symptoms, making it a significant diagnostic challenge requiring high clinical suspicion. 1

Cardinal Clinical Features

Fever and Systemic Symptoms

• Fever is present in up to 90% of patients, often accompanied by:
  • Chills
  • Poor appetite
  • Weight loss 1, 2
• Note: Fever may be absent in elderly patients, immunocompromised individuals, after antibiotic pre-treatment, or with less virulent organisms 1

Cardiac Manifestations

• Heart murmurs are found in up to 85% of patients 1, 2
• New regurgitant heart murmur is a key finding that should immediately raise suspicion 1
• Evidence of congestive heart failure due to valvular dysfunction 2
• New conduction disturbances, particularly atrioventricular blocks (indicating perivalvular extension) 1, 2

Vascular and Immunological Phenomena

• Embolic events occur in approximately 30% of patients and may be the presenting feature 1
• Classic peripheral stigmata include:
  • Splinter hemorrhages
  • Roth spots (retinal hemorrhages with pale centers)
  • Janeway lesions (painless hemorrhagic macules on palms/soles)
  • Osler's nodes (painful nodules on finger/toe pads)
  • Glomerulonephritis 1

Laboratory Findings

• Elevated inflammatory markers (C-reactive protein, erythrocyte sedimentation rate)
• Leukocytosis
• Anemia
• Microscopic hematuria
• Rheumatoid factor positivity 1, 2

Special Clinical Scenarios

Right-Sided IE (Common in Injection Drug Users)

• Pulmonary findings may dominate the clinical picture:
  • Pleuritic chest pain (30% of patients)
  • Abnormal chest radiographs (infiltrates, effusion) in 75-85% of cases
  • Septic pulmonary emboli eventually present in 87% of cases 1
• Signs of tricuspid insufficiency present in only one-third of cases 1
• Often lacks peripheral vascular phenomena seen in left-sided IE 1, 2

Prosthetic Valve Endocarditis

• May have more subtle findings
• Higher risk of perivalvular extension and abscess formation 2
• Requires TEE for adequate evaluation 2

Multivalvular IE

• Present in approximately 20% of IE cases
• Associated with higher risk of complications and mortality compared to single-valve IE 3

Clinical Situations Where IE Should Be Suspected

IE must be suspected in the following situations:

1. New regurgitant heart murmur
2. Embolic events of unknown origin
3. Sepsis of unknown origin (especially if associated with IE causative organism)
4. Fever associated with:
   • Intracardiac prosthetic material (prosthetic valve, pacemaker, implantable defibrillator)
   • Previous history of IE
   • Previous valvular or congenital heart disease
   • Immunocompromised state or injection drug use
   • Recent intervention with associated bacteremia
   • Evidence of congestive heart failure
   • New conduction disturbance
   • Positive blood cultures with typical IE causative organism 1

Diagnostic Challenges

• Atypical presentations are common in elderly or immunocompromised patients 1, 2
• Subacute IE may present with non-specific symptoms that can mislead initial assessment 1
• Diagnostic delays occur due to the variable clinical presentation 1, 2
• Culture-negative endocarditis (up to 20% of cases) often due to prior antibiotic administration 2

Clinical Approach to Suspected IE

When IE is suspected based on clinical features:

1. Obtain at least 3 sets of blood cultures from separate venipuncture sites before starting antibiotics 2
2. Perform echocardiography:
   • TTE as first-line imaging modality
   • TEE if TTE is negative but clinical suspicion remains high, or to better evaluate complications 1, 2
3. Early involvement of a multidisciplinary team (cardiologist, infectious disease specialist) is highly recommended 1

The diverse and evolving nature of IE requires maintaining a high index of suspicion and low threshold for investigation, especially in high-risk groups such as those with prosthetic valves, congenital heart disease, or immunocompromised states 1.