Background: Aortic root abscess (ARA) is a major complication of infective endocarditis that is associated with increased morbidity and mortality. Limited data are present about patient characteristics and outcomes in this lethal disease. We aimed to study the clinical and echocardiographic characteristics of patients with ARA compared to patients with left-sided infective endocarditis without ARA. We included patients with a definite diagnosis of left-sided infective endocarditis according to modified Duke’s criteria. The patients were classified into two groups according to the presence of ARA (ARA and NO-ARA groups). All the patients were studied regarding their demographic data, clinical characteristics, laboratory and imaging data, and complications. Results: We included 285 patients with left-sided infective endocarditis. The incidence of ARA was 21.4% (61 patients). Underlying heart disease, mechanical prosthesis, bicuspid aortic valve, and prior IE were significantly higher in ARA. The level of CRP was higher in ARA (p = 0.03). ARA group showed more aortic valve vegetations (73.8% vs. 37.1%, p < 0.001), more aortic paravalvular leakage (26.7% vs. 4.5%, p < 0.001), and less mitral valve vegetations (21.3% vs. 68.8%, p < 0.001). Logistic regression analysis showed that the odds of ARA increased in the following conditions: aortic paravalvular leak (OR 3.9, 95% CI 1.2–13, p = 0.03), mechanical prosthesis (OR 3.6, 95% CI 1.5–8.7, p = 0.005), aortic valve vegetations (OR 3.0, 95% CI 1.2–8.0, p = 0.02), and undetected organism (OR 2.3, 95% CI 1.1–4.6, p = 0.02), while the odds of ARA decreased with mitral valve vegetations (OR 0.2, 95% CI 0.08–0.5, p = 0.001). We did not find a difference between both groups regarding the incidence of major complications, including in-hospital mortality. Conclusion: In our study, ARA occurred in one fifth of patients with left-sided IE. Patients with mechanical prosthesis, aortic paravalvular leakage, aortic vegetations, and undetected organisms had higher odds of ARA, while patients with mitral vegetations had lower odds of ARA.
