What are the risk factors for endocarditis?

Risk Factors for Infective Endocarditis

The most significant risk factors for infective endocarditis (IE) include prosthetic cardiac valves, previous history of IE, and certain congenital heart diseases, particularly unrepaired cyanotic defects and those with residual defects after repair with prosthetic material. 1

High-Risk Cardiac Conditions

Prosthetic Material

• Prosthetic cardiac valves or prosthetic material used for valve repair - highest risk category with up to 400-fold increased risk compared to general population 1, 2
• Risk is particularly high in the first 12 months after implantation, with hazard ratios of 15-17 in the first year 3
• Long-term risk remains elevated (HR = 5.26) beyond 12 months after valve-containing prosthetic implantation 3

Previous Endocarditis

• History of previous IE significantly increases risk of recurrent infection 1
• Associated with greater risk of complications including heart failure, need for valve replacement, and higher mortality rates 1

Congenital Heart Disease (CHD)

• Unrepaired cyanotic CHD, including those with palliative shunts and conduits 1
• Completely repaired CHD with prosthetic material during the first 6 months after procedure (before complete endothelialization) 1
• Repaired CHD with residual defects at or adjacent to the site of prosthetic patch or device 1
• Highest annualized risk is in patients with repair or palliation of cyanotic CHD, particularly those with obstruction to pulmonary blood flow 1
• Aortic valve stenosis carries increasing cumulative incidence of IE (13.3% at 25 years) 1

Other High-Risk Conditions

• Cardiac transplant recipients who develop valvulopathy 1
• Complex intracardiac repairs with residual hemodynamic abnormalities 1

Procedural Risk Factors

• Central indwelling venous catheters (central lines) - major risk factor, especially in pediatric patients with structurally normal hearts 1
• Dental procedures involving manipulation of gingival tissue or periapical region of teeth 1
• Poor oral hygiene and dental health significantly increase risk of bacteremia during routine daily activities 1

Microbiology Considerations

• Staphylococcus aureus - predominant pathogen, especially in patients with central lines 1, 4
• Viridans streptococci - common in dental-related IE 1
• Right-sided IE is more common in CHD patients than in the general population 4

Important Caveats and Pitfalls

1. Daily activities risk: The vast majority of IE cases likely result from random bacteremias caused by routine daily activities (chewing food, tooth brushing, flossing) rather than from specific procedures 1

2. Non-valve-containing prosthetics: These carry increased risk only in the first 6 months after implantation (HR = 3.34), but not thereafter 3

3. Corrective surgery impact: Complete corrective surgery with no residual defect eliminates the attributable risk for endocarditis in children with ventricular/atrial septal defects or patent ductus arteriosus after 6 months 1

4. Immunodeficiency misconception: Children with congenital or acquired immunodeficiencies without other risk factors do not appear to have increased IE risk compared to the general population 1

5. Adult vs. pediatric differences: Risk factors common in adults (IV drug use, degenerative heart disease) are not common predisposing factors in children 1

The identification of patients at highest risk for IE is essential for appropriate preventive strategies, including antibiotic prophylaxis for high-risk procedures and emphasis on maintaining good oral hygiene and dental health 1.