title: Acute type B aortic dissection in the absence of aortic dilatation.
abstract: BACKGROUND
  Increasing aortic diameter is thought to be an important risk factor for acute type B aortic dissection (ABAD). However, some patients develop ABAD in the absence of aortic dilatation. In this report, we sought to characterize ABAD patients who presented with a descending thoracic aortic diameter <3.5 cm.
  
  
  METHODS
  We categorized 613 ABAD patients enrolled in the International Registry of Acute Aortic Dissection from 1996 to 2009 according to the aortic diameter <3.5 cm (group 1) and ≥3.5 cm (group 2). Demographics, clinical presentation, management, and outcomes of the two groups were compared.
  
  
  RESULTS
  Overall, 21.2% (n = 130) had an aortic diameter <3.5 cm. Patients in group 1 were younger (60.5 vs 64.0 years; P = .015) and more frequently female (50.8% vs 28.6%; P < .001). They presented more often with diabetes (10.9% vs 5.9%; P = .050), history of catheterization (17.0% vs 6.7%; P = .001), and coronary artery bypass grafting (9.7% vs 3.4%; P = .004). Marfan syndrome was equally distributed in the two groups. The overall in-hospital mortality did not differ between groups 1 and 2 (7.6% vs 10.1%; P = .39).
  
  
  CONCLUSIONS
  About one-fifth of patients with ABAD do not present with any aortic dilatation. These patients are more frequently females and younger, when compared with patients with aortic dilatation. This report is an initial investigation to clinically characterize this cohort, and further research is needed to identify risk factors for aortic dissection in the absence of aortic dilatation.
authors.affiliation: Thoracic Aortic Research Center, Policlinico San Donato IRCCS, Milan, Italy. santi.trimarchi@unimi.it
authors.forename: Santi
authors.initials: S
authors.lastname: Trimarchi
authors.forename: Frederik H W
authors.initials: FH
authors.lastname: Jonker
authors.forename: James B
authors.initials: JB
authors.lastname: Froehlich
authors.forename: Gilbert R
authors.initials: GR
authors.lastname: Upchurch
authors.forename: Frans L
authors.initials: FL
authors.lastname: Moll
authors.forename: Bart E
authors.initials: BE
authors.lastname: Muhs
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Rampoldi
authors.forename: Himanshu J
authors.initials: HJ
authors.lastname: Patel
authors.forename: Kim A
authors.initials: KA
authors.lastname: Eagle
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000784:Aortic Dissection / Q000453:epidemiology* / Q000473:pathology; D001013:Aorta, Thoracic / Q000473:pathology*; D017545:Aortic Aneurysm, Thoracic / Q000453:epidemiology* / Q000473:pathology; D050197:Atherosclerosis / Q000453:epidemiology; D004108:Dilatation, Pathologic; D005260:Female; D006801:Humans; D006973:Hypertension / Q000453:epidemiology; D008297:Male; D008382:Marfan Syndrome / Q000453:epidemiology; D008875:Middle Aged; D012042:Registries; D012307:Risk Factors