Mitral annular calcification (MAC) is a chronic inflammatory process, which is common in elderly patients and those with renal dysfunction. MAC is associated with cardiovascular morbidity, and can also be the seat of infective endocarditis (IE).

The aim of this study was to test the hypothesis that IE on MAC would be prevalent in patients with renal dysfunction and more comorbidities, and thus would have more complications.

We retrospectively reviewed in our center, all patients diagnosed with IE according to modified Dukes criteria from December 2007 to December 2016. MAC was defined as focal echo-brightness in a nodular or band-like pattern.

We find 119 patients with IE, whose 55 IE (46.2%) were on mitral valve, including 39 (32.7%) on native valve and 13 (10.9%) on MAC. Staphylococcus aureus was the infecting organism of 9/13 (69.2%) MAC vs. 24/106 (22.6%) of all other IE (P=0.02); 11/42 (26.1%) of IE on mitral valve (prosthetic and native) (P=0.01); and 6/26 (23.0%) of IE on only native mitral (P=0.01). More abscess were find in MAC group: 10/13 (76.9%) vs. 27/106 (25.5%) of all other IE (P<0.001); 9/42 (21.4%) of IE on mitral valve (prosthetic and native) (P<0.001); 6/26 (23.1%) of IE on only native mitral valve (P=0.02). Patient in the MAC group tend to have more renal dysfunction with clearance of creatinine at 53.5 vs. 74.8 P=0.093 and a longer time to negativate hemocultures (5.6 days versus 3.92; P=0.066). We don’t find any difference on the prevalence of embolisis, death, Charlson score, or diagnostic help of transesophageal echography.

MAC appears to be more often infected by Staphylococcus aureus. As it's also a predisposing factor for abscess, we think that repeated echography could allow a better track of IE on elderly patient with septicemia with Staphylococcus aureus, especially when hemocultures negativate later.