title: Mitral Annular Calcification as a Possible Nidus for Endocarditis: A Descriptive Series with Bacteriological Differences Noted.
abstract: BACKGROUND
  Mitral annular calcification (MAC) is a chronic inflammatory process with similarities to atherosclerosis. It is common in elderly patients and those with renal dysfunction. Although MAC is associated with cardiovascular morbidity, its relationship to infective endocarditis is unclear. The aim of this study was to test the hypothesis that MAC would be prevalent in patients with mitral valve vegetations and that vegetations would frequently occur on calcific nodules. A secondary aim was to look for possible bacteriological differences between vegetations attached to the calcified annulus versus leaflet vegetations.
  
  
  METHODS
  We retrospectively reviewed all echocardiographic studies of patients with native mitral valve vegetations from January 2007 to August 2015 (N = 56). We searched for (1) presence of MAC, (2) location of MAC, and (3) vegetation location (on calcium deposits or distant). MAC was defined as focal echo brightness in a nodular or band-like pattern. The modified Duke criteria were used to confirm the diagnosis of infective endocarditis. Transthoracic, transesophageal, and three-dimensional echocardiograms (when available) at the time of infection were evaluated by a single reader.
  
  
  RESULTS
  Twenty-eight subjects were infected with Staphylococcus aureus, 17 with a streptococcal species, and five with other organisms; blood cultures were sterile in 6. Thirty-four (61%) subjects had some degree of MAC, while 22 (39%) had none. Among those with MAC, the vegetation was located on the calcium deposits in 22 (65%), versus in 12 (35%) where it was not. Among all 56 subjects, when S. aureus was the infecting organism it was present on MAC in 16/28 (57%) versus 6/28 (21%; P = .01) for other bacterial species. By contrast, streptococcal infections more frequently involved the leaflets (16/17 [94%]) versus nonstreptococcal infections (18/39 [46%]; P = .0008).
  
  
  CONCLUSIONS
  MAC may act as a nidus for infection especially with S. aureus. Differences in mechanism of attachment between S. aureus and streptococci may account for the observed difference in frequency of attachment of vegetations to MAC.
authors.affiliation: Division of Cardiology, Heart and Vascular Institute, Einstein Medical Center, Philadelphia, Pennsylvania. Electronic address: pressmang@einstein.edu.
authors.forename: Gregg S
authors.initials: GS
authors.lastname: Pressman
authors.affiliation: Department of Medicine, Einstein Medical Center, Philadelphia, Pennsylvania.
authors.forename: Mary
authors.initials: M
authors.lastname: Rodriguez-Ziccardi
authors.affiliation: Philadelphia College of Osteopathic Medicine, Philadelphia, Pennsylvania.
authors.forename: Charles H
authors.initials: CH
authors.lastname: Gartman
authors.affiliation: Division of Cardiology, Heart and Vascular Institute, Einstein Medical Center, Philadelphia, Pennsylvania.
authors.forename: Edinrin
authors.initials: E
authors.lastname: Obasare
authors.affiliation: Department of Medicine, Einstein Medical Center, Philadelphia, Pennsylvania.
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Melendres
authors.affiliation: Department of Pathology, Einstein Medical Center, Philadelphia, Pennsylvania.
authors.forename: Vivian
authors.initials: V
authors.lastname: Arguello
authors.affiliation: Division of Cardiology, Heart and Vascular Institute, Einstein Medical Center, Philadelphia, Pennsylvania.
authors.forename: Vikas
authors.initials: V
authors.lastname: Bhalla
mesh_terms: D000368:Aged; D002114:Calcinosis / Q000000981:diagnostic imaging* / Q000453:epidemiology* / Q000382:microbiology; D015984:Causality; D015897:Comorbidity; D003937:Diagnosis, Differential; D019560:Echocardiography, Three-Dimensional; D004697:Endocarditis, Bacterial / Q000000981:diagnostic imaging / Q000453:epidemiology* / Q000382:microbiology; D005260:Female; D006349:Heart Valve Diseases / Q000000981:diagnostic imaging* / Q000453:epidemiology* / Q000382:microbiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D008943:Mitral Valve / Q000000981:diagnostic imaging* / Q000382:microbiology; D010414:Pennsylvania / Q000453:epidemiology; D011379:Prognosis; D015203:Reproducibility of Results; D018570:Risk Assessment; D012680:Sensitivity and Specificity; D013203:Staphylococcal Infections / Q000175:diagnosis / Q000453:epidemiology* / Q000382:microbiology
keywords: Infective endocarditis; Mitral annular calcification; Staphylococcus aureus; Vegetation