Comparing clinical outcomes in bicuspid versus trileaflet aortic valve endocarditis

Abstract

Abstract Background The incidence of bicuspid aortic valve infective endocarditis (BAV-IE) has been reported at 2% in contemporary BAV cohorts with an estimated risk of developing BAV-IE 11 times that of the general population with a trileaflet aortic valve (TAV). Purpose To characterise BAV-IE from a clinical and microbiological perspective and compare clinical outcomes with a cohort of individuals with trileaflet aortic valve infective endocarditis (TAV-IE). Methods The clinical records of all patients (>16 years old) admitted to a large tertiary referral centre in the United Kingdom between 2015 and 2022 with a definitive diagnosis of native aortic valve IE by Duke’s criteria were included. Clinical, echocardiographic and microbiological data were obtained. The primary outcomes were death or surgical aortic valve intervention during the indexed hospital admission. Secondary outcomes included the incidence of cardiac complications (e.g. aortic root abscess or fistula formation, IE affecting another valve or high degree atrioventricular block requiring temporary or permanent pacing). Extra-cardiac complications included embolic phenomena and thrombotic events. Results 83 patients were included (BAV-IE 34; TAV-IE 49). BAV-IE patients were significantly younger at presentation than TAV-IE patients (Table 1). There was no difference age-adjusted mortality rate between the two groups (mortality rate BAV-IE 0.20 (95% CI 0.08-0.54) versus TAV-IE 0.29 (95% CI 0.17-0.48). The rate of cardiac complications including aortic root abscess or fistula formation, and concomitant mitral valve endocarditis was greater in the BAV group, though not reaching statistical significance. Those in the BAV-IE group were more likely to develop at least moderate aortic regurgitation and have aortic valve intervention during the admission (70.6% (24/34) BAV-IE versus 46.9% (23/49) TAV-IE, p=0.03). Conclusion Despite an estimated prevalence of 1% in the general population, BAV accounted for 41% of all native AV IE cases at our institution. This study demonstrates that even in young, otherwise healthy individuals, BAV-IE has a poor prognosis with a high proportion developing structural complications. Age-adjusted mortality rates are similar to those with TAV-IE, who are often older with more co-morbidities. Though antibiotic prophylaxis is currently only recommended for those at the highest risk, these findings reinforce the importance of mitigating sources of infection in individuals with BAV. Prompt medical attention and treatment of suspected IE cases is of utmost importance as degeneration of a BAV and other cardiac complications, particularly aortic regurgitation, can rapidly develop.