Exploring sex differences in infective endocarditis - a prospective, observational study from Western Norway.

Background: We aimed to investigate sex-differences among patients with infective endocarditis (IE) in Western Norway, focusing on clinical presentation, treatment strategies, and outcomes.

Methods: This prospective observational study included 131 females, and 366 males diagnosed with IE between 2016 and 2022. Clinical and microbiological characteristics were analysed using chi-squared or Fisher's exact tests, while survival data were assessed via Kaplan-Meier estimates and multiple Cox regression models.

Results: The mean age was 69 years for females and 66 years for males (p = 0.317).

Primary outcomes: Mortality rates were significantly higher in females at 30 days (13% vs. 7%, p = 0.028), at 90 days (19% vs. 11%, p = 0.016), and overall (46% vs. 36%, p = 0.016), with a mean follow-up of 3.2 years (± 2.3 years).

Secondary outcomes: The mitral valve was more frequently affected in females than in males (31% vs. 17%, p < 0.001), and Staphylococcus aureus more often the microbial cause (36% vs. 27%, p = 0.049). While surgical treatment rates were similar (26% of females and 34% of males, p = 0.075), females with aortic valve IE underwent surgery at a significantly lower rate (23% vs. 39%, p = 0.001) and experienced longer delays before surgery (median 25 vs. 21 days, p = 0.043). Multivariable analysis identified higher age (HR 1.02, 95% CI 1.00-1.04, p = 0.014) and mitral valve infection (HR 2.88, 95% CI 1.57-5.29, p < 0.001) as independent predictors of 90-day mortality, while surgery significantly improved survival (HR 0.38, 95% CI 0.17-0.81, p = 0.013).

Conclusions: Mitral valve IE was more common in females and strongly associated with higher mortality. Females with IE had higher mortality rates, more frequent mitral valve involvement, and a greater incidence of S. aureus infections. Despite the clear survival benefit of surgery, females with aortic valve IE underwent fewer and later surgeries. These findings highlight potential sex disparities in IE management and emphasize the need for further research into sex-based differences in treatment strategies and outcomes.