Mycotic aneurysm (MA) is rare but is a serious complication of infective endocarditis (IE).

To evaluate the epidemiological, microbiological, diagnostic, therapeutic and prognostic data of patients with this complication.

In a French bi-center prospective study of patients who presented in our endocarditis reference centers with a diagnosis of definite IE from 1988 to 2017 (n=2483), 101 (4%) presented MA.

Patients with MA were younger (56 vs. 67y, P<0.001), more often male (83% vs. 71%, P=0.007), intravenous drug users (13% vs. 5%, P<0.001). Diabetes (5% vs. 15%, P=0.004), neoplasia (9% vs. 16%, P=0.049), history of valve replacement (31% vs. 21%, P=0.031) and cardiac device (5% vs. 20%, P<0.001) were less frequent in MA group. Positive blood cultures were more frequent in MA group (97% vs. 81%). MA group had more aortic and mitral location (63% vs. 48%, p=0.006 and 53% vs. 42%, P=0,034, respectively) with more aortic perforation (25% vs. 14%, P=0.002). Septic emboli were more frequents in MA group (81% vs. 41%, P<0.001) regarding cerebral septic emboli (57% vs. 17%, P<0.001), non-cerebral emboli (39% vs. 22%, p<0.001) and multiple septic emboli (25% vs. 8%, P<0.001). MA group had more cerebral events: ischemic stroke (33% vs. 12%, P<0.001), intracranial hemorrhage (33% vs. 3%, P<0.001). The indication of cardiac surgery was more frequent in the MA group (83% vs. 70%, P=0.007) but the delay to surgery was longer (20 vs. 13 days, P=0.029). Regarding the evolution, MA group had higher in-hospital mortality (22% vs. 13%, p0.014) and poorer 1-month survival (65% vs. 80%, P=0.045) but the one-year mortality did not differ (52% vs. 49%, P=0.79).

Our data highlight that MA in IE is associated with poor short-term prognosis, mainly due to neurological complications in his younger population. One of the future challenges should be the improvement of the diagnostic of MA in IE.