To examine the added value of an elevated calculated peak right ventricular outflow tract pressure gradient as a surrogate for infective endocarditis diagnosis.

A cohort study included patients admitted between 2003 and 2020 at a tertiary children’s medical centre. Patients with surgically inserted exogenous right ventricular outflow tract conduits and infective endocarditis were included. Infective endocarditis was diagnosed using the revised Duke criteria (2023). Controls had right ventricular outflow tract conduits and febrile illness from other causes. Clinical, laboratory, and echocardiographic findings, including calculated peak right ventricular outflow tract pressure gradient, were collected.

Among 26 febrile episodes (11 with infective endocarditis, 15 controls), the infective endocarditis group had a higher peak right ventricular outflow tract pressure gradient during acute illness (70 vs. 23 mmHg, p < 0.05). On admission, 18% of infective endocarditis patients had a definite diagnosis by Duke’s criteria, 45% had a probable diagnosis, and 36% lacked confirmation. Including peak right ventricular outflow tract gradient as a major criterion would yield a 90% diagnosis rate upon admission (45% definite, 45% possible).

Increased right ventricular outflow tract pressure gradient in febrile patients with exogenous conduit in the right ventricular outflow tract is a potential marker for infective endocarditis. Including this gradient as a major Duke criterion enables earlier and more definitive diagnosis in debatable cases.