Objective To analyse characteristics and outcomes of infective endocarditis (IE) on bicuspid aortic valves (BAV) and to compare the risk of death according to the presence or absence of BAV.

Design 5-year observational study.

Setting Population of 856 patients with definite IE according to the Duke criteria from two tertiary centres (Amiens and Marseille, France).

Patients 310 consecutive patients with definite native aortic valve IE enrolled between 1991 and 2007.

Interventions Patients underwent transthoracic and transoesophageal echocardiography during hospitalisation. Surgery was performed on a case-by-case basis according to conventional guidelines.

Main outcome measures In-hospital mortality and 5-year overall mortality.

Results Patients with BAV IE (n=50, 16%) were younger, had fewer comorbidities and a higher frequency of aortic perivalvular abscess (50%). Presence of BAV (OR 3.79 (1.97–7.28); p<0.001) was independently predictive of abscess formation. Early surgery was performed in 36 BAV patients (72%) with a peri-operative mortality of 8.3%, comparable to that of patients with tricuspid aortic valve IE (p=0.89). BAV was not independently predictive of in-hospital mortality (OR 0.89 (0.28–2.85); p=0.84) or 5-year survival (HR 0.71 (0.37–1.36); p=0.30). Age, comorbidities, heart failure, Staphylococcus aureus and uncontrolled infection were associated with increased 5-year mortality in BAV patients.

Conclusion BAV is frequent in adults with native aortic valve IE. Patients with BAV IE incur high risk of abscess formation and require early surgery in almost three-quarters of cases. IE is a severe complication in the setting of BAV and warrants prompt diagnosis and treatment.