The Cardiovascular Diseases and Infectious Diseases groups at the Vall d’Hebron Research Institute (VHIR) have analysed differences between patients who underwent surgery for endocarditis of the valves on the left side of the heart. The study shows that women have higher mortality during the 30 days following surgery and highlights the need to understand the cause of these differences in order to improve outcomes. The study, conducted with 1,085 patients, has been published in the journal Clinical Microbiology and Infection.

Infective endocarditis is an inflammation of the inner lining of the heart and its valves caused by an infection. It can particularly affect valves that have already sustained some previous damage and, among the different sites affected, the mitral and aortic valves, located on the left side of the heart, are particularly relevant.

It is an uncommon but serious disease. Initial treatment is usually based on antibiotics, but in the most severe cases or when certain complications arise, surgery is necessary to repair or replace the affected valve. In Catalonia, approximately 100 to 120 people undergo surgery for endocarditis each year. “Surgery carries considerable risk, especially when it has to be performed urgently. It is therefore important to be able to estimate the surgical risk as accurately as possible and to have tools that help us make decisions tailored to each patient,” explains Marco Tomasino, who conducted the study as a member of the Cardiology Department at Vall d’Hebron University Hospital and a researcher in the Cardiovascular Diseases group at VHIR.

The first international prospective registry of patients undergoing surgery for endocarditis

To improve knowledge of the risk associated with surgery for endocarditis, Vall d’Hebron has launched the BESOS registry (Barcelona Endocarditis Surgery Outcome Score), the first international prospective registry of patients undergoing surgery for endocarditis, collecting data on procedures performed during 2025 from 55 centres in 19 countries.

Unlike retrospective studies, which analyse information previously collected from medical records, the BESOS registry has collected data from the moment each patient is enrolled. This makes it possible to obtain more complete and consistent information on the progression of the disease and the surgical procedure.

Higher 30-day mortality among women undergoing surgery for endocarditis

In this first study based on the registry, 1,085 patients who underwent surgery for endocarditis of the mitral or aortic valves were specifically analysed, 239 of whom were women. The study analysed differences between men and women in the characteristics of the disease.

Regarding the characteristics of the disease, differences between the sexes were observed in several aspects. Staphylococcus aureus infection and mitral valve involvement were more common among women, while Enterococcus faecalis infection and aortic valve involvement were more common among men. Greater frailty was also observed among women, that is, a situation of greater dependence or vulnerability. These differences may influence the risk associated with surgery.

The results show higher mortality among women 30 days after surgery. Specifically, mortality was 21% in women, compared with 11% in men. “Even after adjusting the results for patients’ baseline characteristics, a significant difference in mortality between men and women remains,” highlights Dr. Núria Fernández-Hidalgo, consultant in the Infectious Diseases Department and head of the Multidisciplinary Infective Endocarditis Committee at Vall d’Hebron University Hospital, and a researcher at the Infectious Diseases group at VHIR.

Why is mortality higher in women?

The study does not yet make it possible to determine the cause of these differences between men and women. The research team has put forward several hypotheses that will need to be studied in future research.

One possibility is that women undergo surgery in a more severe condition. For example, this could be due to a delay in diagnosing endocarditis, starting antibiotic treatment or performing surgery.

Another hypothesis that could explain the higher mortality among women is a different biological response to cardiac surgery. For example, women have a greater tendency to develop certain complications associated with cardiopulmonary bypass, a technique required during this type of procedure, which could influence survival in the days following surgery.

“In future studies, it will be important to analyse the entire care pathway in detail and to better understand what happens during and after the procedure in men and women. This information may help identify patients at higher risk and develop specific strategies to reduce complications and improve surgical outcomes”, says Dr. Ignacio Ferreira, head of the Cardiology Department at Vall d’Hebron University Hospital and of the Cardiovascular Diseases group at VHIR.

In parallel, as part of the BESOS study, the team is developing a new prognostic score specifically for people with endocarditis who require surgery. This tool will make it possible to estimate the risk associated with surgery more accurately and could contribute to more personalised decision-making and follow-up for each patient.

The project has received funding from the Spanish Society of Cardiology. In addition, over the past year, Marco Tomasino has been the recipient of a Carles Margarit post-residency fellowship from VHIR, made possible through financial contributions from the Amics de Vall d’Hebron.