Infective Endocarditis

Written by Dr Andrew Lam

Infective Endocarditis

Modified Duke’s Criteria

Infective Endocarditis can be definitively diagnosed in the presence of:

2 Major Criteria, OR

1 Major and 3 Minor Criteria, OR

5 Minor Criteria

Major Criteria: 

• Micro-Organisms consistent with IE isolated from 2 separate blood cultures 
• Evidence of myocardial involvement (i.e. Echocardiogram positive for IE or new valvular regurgitation)

Minor Criteria: 

• Temperature (>38°C)
• Predisposing Risk Factors (i.e. IV Drug Use, prosthetic heart valve)
• Vascular Phenomena (arterial embolisation, septic pulmonary infarction, mycotic aneurysm, Janeway lesions)
• Immunological Phenomena (i.e. glomerulonephritis, Osler’s Nodes, Roth Spots)
• Positive blood cultures that do not meet major criteria

Risk Factors

• IV Drug Use (promotes bacterial seeding, typically affects tricuspid valve)
• Poor dentition or recent dental surgery
• Structural heart disease (i.e. HOCM, VSD, aortic coarctation, congenital or acquired valvular disease)
• Prosthetic heart valves 
• Intravascular Devices (i.e. central venous catheters, pacemakers, ICD’s)

Complications

Local Complications

• Heart failure (right or left dependent on valve involved)
• A perivalvular abscess (Can result in conduction blocks/arrhythmias)
• Pericarditis

Systemic Complications

• Septic Arterial Embolisation (stroke, splenic/renal infarction, myocardial infarction, pulmonary embolism)
• Metastatic Abscess (secondary to septic embolisation
• Mycotic Aneurysm (usually at points of vessel bifurcation)
• Osteomyelitis or Septic Arthritis
• Glomerulonephritis (immune complex-mediated)

References: 

Sexton, D.J., Chu, V.H., (2020). Clinical manifestations and evaluation of adults with suspected left-sided native valve endocarditis. UpToDate. Retrieved May 1, 2021, from https://www.uptodate.com.acs.hcn.com.au/contents/clinical-manifestations-and-evaluation-of-adults-with-suspected-left-sided-native-valve-endocarditis

Sexton, D.J., Chu, V.H., (2021). Native valve endocarditis: Epidemiology, risk factors, and microbiology. UpToDate. Retrieved May 1, 2021, from https://www.uptodate.com.acs.hcn.com.au/contents/native-valve-endocarditis-epidemiology-risk-factors-and-microbiology

Spelman, D., (2021). Complications and outcome of infective endocarditis. UpToDate. Retrieved May 1, 2021, from https://www.uptodate.com.acs.hcn.com.au/contents/complications-and-outcome-of-infective-endocarditis