Surgery for Active Infective Endocarditis on Mitral Valve: Anatomical, Surgical, and Disease Factors as Long-Term Outcome Modifiers

Background and Objectives: Determinants of long-term outcomes after surgery for native mitral valve endocarditis have not been thoroughly investigated. The aim of this study was to assess anatomical, disease, and surgical risk factors for long-term mortality and need of reintervention, in patients undergoing mitral valve surgery for active endocarditis. Materials and Methods: Patients who underwent surgery for active native mitral valve endocarditis at three academic centres, between 2000 and 2022, were analysed. The primary outcome was long-term survival. The secondary outcome was the freedom from mitral reoperation. Survival curves were constructed with Kaplan–Meier methodology. Multivariable Cox regression was used to identify demographic, anatomical, disease, and surgical factors associated with late mortality and reoperation. Results: 335 consecutive patients with active mitral endocarditis were analysed. Two hundred and one patients (70.5%) had infection confined to the valve cusp whereas 89 (25.6%) had invasive disease extended to the annulus and surrounding tissues. Preoperative neurological events occurred at the diagnosis in 52 cases. Streptococci were the most common causative organisms followed by Staphylococcus aureus, Coagulase-negative Staphylococcus, and Enterococcus. Valve repair was performed in 108 patients (32.2%). Survival at 5 and 10 years was 70.1% and 59.2%, respectively. Staphylococcus emerged as an independent predictor of late mortality, along with age, chronic obstructive pulmonary disease, and previous cardiac surgery. Survival was considerably reduced in patients with S. aureus compared with those without (log rank p < 0.001). The type of surgery (repair vs. replacement) did not emerge as a risk factor for late mortality and reoperation. Seventeen patients underwent mitral reoperation during the follow-up. The 5- and 10-year freedom from reoperation was 94.7% and 91.8%, respectively. Conclusions: Active mitral valve endocarditis remains a life-threatening disease with impaired survival. While lesion characteristics influenced surgical decision-making and intraoperative management, their impact on long-term survival and freedom from reintervention appears to be moderated by other factors such as infecting pathogens and patient comorbidities.