Despite enormous developments in medicine, infective endocarditis (IE) remains an ongoing issue for physicians due to increased morbidity and persistently high mortality. Our goal was to assess clinical outcomes in patients with IE and identify determinants of in-hospital mortality. Material and methods: The analysis was retrospective, single-centered, and comprised 270 patients diagnosed with IE from 2005 to 2021 (median age 65 (51–74), male 177 (65.6%). Native IE (NVIE) was observed in 180 (66.7%), prosthetic IE (PVIE) in 88 (33.6%), and cardiac device-related IE (CDRIE) in 2 (0.7%), with non-survivors having much higher rates. Healthcare-associated IE (HAIE) was 72 (26.7%), Staphylococci were the most prevalent pathogen, and the proportion of Gram-negative bacteria (GNB) non-HACEK was significantly greater in non-survivors than survivors (11 (15%) vs. 9 (4.5%), p = 0.004). Overall, 54 (20%) patients underwent early surgery, with a significant difference between dead and alive patients (3 (4.5%) vs. 51 (25.1%, p = 0.000). The overall in-hospital mortality rate was 24.8% (67). Logistic regression was conducted on the total sample (n = 270) for the period 2005–2021, as well as the sub-periods 2005–2015 (n = 119) and 2016–2021 (n = 151), to identify any differences in the trend of IE. For the overall group, the presence of septic shock (OR-83.1; 95% CI (17.0–405.2), p = 0.000) and acute heart failure (OR—24.6; 95% CI (9.2–65.0), p = 0.000) increased the risk of mortality. Early surgery (OR-0.03, 95% CI (0.01–0.16), p = 0.000) and a low Charlson comorbidity index (OR-0.85, 95% CI (0.74–0.98, p = 0.026) also lower this risk. Between 2005 and 2015, the presence of septic shock (OR 76.5, 95% CI 7.11–823.4, p = 0.000), acute heart failure (OR-11.5, 95% CI 2.9–46.3, p = 0.001), and chronic heart failure (OR-1.3, 95% CI 1.1–1.8, p = 0.022) enhanced the likelihood of a fatal outcome. Low Charlson index comorbidity (CCI) lowered the risk (OR-0.7, 95% CI 0.5–0.95, p = 0.026). For the period 2016–2021, the variable with the major influence for the model is the failure to perform early surgery in indicated patients (OR-240, 95% CI 23.2—2483, p = 0.000) followed by a complication of acute heart failure (OR-72.2, 95% CI 7.5–693.6. p = 0.000), septic shock (OR-17.4, 95% CI 2.0–150.8, p = 0.010), previous stroke (OR-9.2, 95% CI 1.4–59.4, p = 0.020) and low ejection fraction (OR-1.1, 95% CI 1.0–1.2, p = 0.004). Conclusions: Knowing the predictors of mortality would change the therapeutic approach to be more aggressive, improving the short- and long-term prognosis of IE patients.