INTRODUCTION AND OBJECTIVES In infective endocarditis (IE), decisions on surgical interventions are challenging and a high percentage of patients with surgical indication do not undergo these procedures. This study aimed to evaluate the short- and long-term prognosis of patients with surgical indication, comparing those who underwent surgery with those who did not. METHODS We included 271 patients with left-sided IE treated at our institution from 2003 to 2018 and with an indication for surgery. There were 83 (31%) surgery-indicated not undergoing surgery patients with left-sided infective endocarditis (SINUS-LSIE). The primary outcome was all-cause death by day 60 and the secondary outcome was all-cause death from day 61 to 3 years of follow-up. Multivariable Cox regression and propensity score matching were used for the analysis. RESULTS At the 60-day follow-up, 40 (21.3%) surgically-treated patients and 53 (63.9%) SINUS-LSIE patients died (P