Incidence of Infective Endocarditis in Ventricular Septal Defect
The incidence of infective endocarditis (IE) in adults with unrepaired VSD is approximately 1.7-2.7 per 1000 patient-years, representing a 20-30 fold increased risk compared to the general population. 1
Risk Stratification by VSD Status
Unrepaired VSDs
- Small, hemodynamically insignificant VSDs carry the highest documented risk, with an incidence of 1.67-1.90 per 1000 patient-years 1, 2
- This translates to approximately 11-30 times the risk seen in the general adult population 1, 2
- The European Society of Cardiology reports IE occurring in up to 2 per 1000 patient-years in patients with small residual VSDs 3
- Importantly, at least 22% of patients with surgically repaired VSDs who developed IE had known residual VSD leaks 3
Completely Repaired VSDs
- Corrective surgery with no residual defect eliminates the attributable risk for endocarditis 6 months after surgery 3
- In two recent cohort studies, zero cases of IE occurred in patients with isolated, completely repaired VSDs during 10-year follow-up periods 1, 2
- The risk before surgical closure is more than twice that of surgically closed VSDs 3
Important Clinical Context
Mortality and Morbidity Considerations
- Mortality from IE in patients with small unoperated VSDs is low, with no deaths reported in one series of 13 patients 1
- However, patients with repaired VSDs who have additional valve pathology (e.g., bicuspid aortic valve, previous aortic valve replacement) face significantly higher mortality and often require reoperation 1
- The presence of aortic regurgitation independently increases the risk of IE in patients with VSD, whether managed medically or surgically 3
Risk Factors That Amplify IE Risk
- Residual defects at or adjacent to prosthetic patches that inhibit endothelialization remain high-risk 3
- Unrepaired cyanotic congenital heart disease carries substantially higher IE risk than isolated VSDs 3
- The predominant organism in VSD-associated IE is viridans streptococcus, with the incidence rate nearly 35-fold the population-based rate 3
Critical Pitfalls to Avoid
Do not assume all "repaired" VSDs have equal risk—carefully assess for residual shunts, as these patients retain elevated IE risk comparable to unrepaired defects 3, 1. The distinction between complete repair and repair with residual leak is clinically crucial for risk stratification and prophylaxis decisions.