Infective endocarditis in congenital heart disease: a frequent community-acquired complication.

Background: Infective endocarditis (IE) is a severe complication in patients with congenital heart disease (CHD). Epidemiology, etiology, and outcome in this group are different to those of patients with acquired heart disease.

Methods: We reviewed all cases of proven and probable IE (Duke's criteria) diagnosed in our center during the last two decades.

Results: We observed 45 cases of IE in patients with CHD (age range 8 months to 35 years); these represented 5.5 % of all the episodes of IE in our institution during the study period. The most frequent CHD were ventricular septal defect (31 %), tetralogy of Fallot (19 %), and atrioventricular septal defect (11 %). Twenty cases of IE (44 %) were recorded in patients with non-corrected native-valve CHD. Of the 24 patients with prosthetic-valve IE, post-operative acquisition during the first 6 months was confirmed in 11 patients (range 4-110 days). IE was community-acquired in 62 % of cases. Streptococcus spp. were the most frequent etiologic agents (33 %), followed by Staphylococcus spp. (32 %). Surgery was required to treat IE in 47 % of patients (52 % in prosthetic-valve IE and 41 % in native-valve IE, p = ns). In comparison to native-valve IE, prosthetic-valve IE was significantly more nosocomial-acquired (61 vs. 14 %, p = 0.002), presented a higher heart failure rate at diagnosis (39 vs. 9 %, p = 0.035), and developed more breakthrough bacteremia episodes (19 vs. 0 %, p = 0.048). Global mortality was 24 % (75 % in patients with prosthetic-valve IE who required surgery and 0 % in patients with native-valve IE who required surgery, p = 0.001). Multivariate analysis excluding breakthrough bacteremia (100 % mortality in this condition) confirmed that nosocomial IE [odds ratio (OR), 23.7; 95 % confidence interval (CI), 2.3-239.9] and the presence of heart failure at diagnosis of IE (OR, 25.9; 95 % CI, 2.5-269.6) were independent factors associated with mortality.

Conclusion: Half of all cases of IE in patients with CHD occurred in patients with non-corrected native-valve CHD and two-thirds were community-acquired. Streptococcus spp. were the most frequent etiological agents. Patients with prosthetic-valve IE present a worse outcome, especially those requiring surgery. Breakthrough bacteremia, nosocomial IE, and heart failure are independent factors of mortality in patients with CHD presenting IE.