Cardiac surgery for correction or palliation of congenital cardiac disease in infancy and childhood remains a privilege that is rarely accessible to two-thirds of the world’s population. This imbalance has created a unique spectrum of illness in patients with underlying congenital cardiac disease and complicating infective endocarditis in developing countries, including Pakistan. In this study, we characterize endocarditis as seen in such patients presenting in Karachi.

We reviewed retrospectively patients admitted to Aga Khan University with underlying congenitally malformed hearts and endocarditis between 1991 and 2004.

We identified 48 patients with endocarditis according to the modified Duke Criterions, with just over half the cases (54%) classified as definite endocarditis. Of the patients, 23 (49%) patients were more than 16 years old. Uncorrected left-to-right-shunts, tetralogy of Fallot, and congenital mitral valvar disease were the most common underlying defects. Patients with cyanotic defects, particularly of the complex type, were underrepresented (4%). Only 11 (22.9%) of the patients had a previous palliative or corrective surgery. In one-third of the patients (16), streptococcal species were identified as the microbiologic cause of endocarditis, and 22 (45.8%) had culture-negative endocarditis. In contrast, Staphylococcus aureus and enterococci caused endocarditis in only one patient each. There were no differences in mortality or complications between cyanotic and acyanotic congenital defects. Surgery was performed in nine (18.7%) patients with endocarditis, and of these, 13 (27.1%) died.

In contrast to the developed world, endocarditis in the developing countries, such as Pakistan, complicates uncorrected left-to-right shunts and tetralogy of Fallot, probably because patients with complex cyanotic defects fail to survive long after birth due to the lack of available surgery. Almost half of patients had culture-negative endocarditis, likely related to several factors.