Native Valve Infective Endocarditis with Severe Regurgitation: What Matters Is Heart Failure

<b>Background/Objectives:</b> Heart failure worsens the prognosis of patients with infective endocarditis (IE) and is mainly caused by severe valvular regurgitation. The aim of our investigation is to describe the clinical, epidemiological, microbiological, and echocardiographic characteristics of patients with native left-sided infective endocarditis (NLSIE) with severe valvular regurgitation; to describe the prognosis according to the therapeutic approach; and to determine the prognostic factors of in-hospital mortality. <b>Methods</b>: We prospectively recruited all episodes of possible or definite NLSIE diagnosed at three tertiary hospitals between 2005 and 2022. Patients were divided into two groups: patients with severe valvular regurgitation at the time of admission or during hospitalization and patients without severe valvular regurgitation. We analyzed up to 85 variables concerning epidemiological, clinical, analytical, microbiological, and echocardiographic data. <b>Results</b>: We recovered 874 patients with NLSIE, 564 (65%) of them with severe valvular regurgitation. There were no differences in mortality among patients with and without severe regurgitation (30.2% vs. 26.5%, <i>p</i> = 0.223). However, mortality increased when patients with severe regurgitation developed heart failure (33% vs. 11.4%, <i>p</i> < 0.001). Independent factors related to heart failure were age (OR 1.02 [1.01-1.034], <i>p</i> = 0.001), anemia (OR 1.2 [1.18-3.31], <i>p</i> = 0.01), atrial fibrillation (OR 2.3 [1.08-4.89], <i>p</i> = 0.03), <i>S. viridans</i>-related IE (OR 0.47 [0.3-0.73], <i>p</i> = 0.001), and mitroaortic severe regurgitation (OR 2.4 [1.15-5.02], <i>p</i> = 0.019). <b>Conclusions</b>: Severe valvular regurgitation is very frequent among patients with NLSIE, but it does not worsen the prognosis of patients unless complicated with heart failure.