title: Prevalence of left atrial appendage pseudothrombus filling defects in patients with atrial fibrillation undergoing coronary computed tomography angiography.
abstract: BACKGROUND
  Previous reports have shown that computed tomography (CT) is a useful, noninvasive test for detecting atrial thrombi. However, blood stasis in the left atrial appendage (LAA) of patients with atrial fibrillation (AF) may be a common cause for false-positive results.
  
  
  OBJECTIVE
  We retrospectively evaluated the prevalence of filling defects that may simulate thrombus in the LAA of patients with AF during routine coronary CT angiography (CTA).
  
  
  METHODS
  The LAA of 7 patients with AF was studied for the presence of filling defects and compared with 250 healthy persons. LAA volume in the patients with AF was measured at 10 different cardiac phases and compared with 30 healthy patients.
  
  
  RESULTS
  Of the 7 patients with AF studied with CTA, 5 were positive for LAA filling defects. Follow-up imaging studies, including transesophageal echocardiogram, contrast-enhanced magnetic resonance angiography, or delayed-CT, were negative for LAA thrombus. Of 250 patients without AF, CTA showed no evidence of LAA filling defects. Patients with AF had significantly larger LAA volumes at all cardiac phases measured compared with patients without AF (15.2 +/- 6.93 mL compared with 6.85 +/- 3.01 mL at atrial contraction [P = 0.0187], 17.4 +/- 7.76 mL compared with 9.46 +/- 3.43 mL at ventricular systole [P = 0.0351], and 14.5 +/- 5.87 mL compared with 8.48 +/- 3.10 mL at mid-diastole [P = 0.0341]). Compared with the healthy persons, the patients with AF showed reduced percentages of change in LAA volume when the atrial contraction phase was compared with other phases: 44.0% +/- 25.6% compared with 16.5% +/- 12.2% compared with ventricular systole (P = 0.0004) and 29.5% +/- 23.7% compared with -1.63% +/- 8.84% at mid-diastole (P < 0.0001).
  
  
  CONCLUSIONS
  Pseudothrombus filling defects are common in the LAA of patients with AF undergoing coronary CTA and should not be mistaken for real thrombus.
authors.affiliation: Department of Radiological Sciences, University of California Irvine, UCI Medical Center, Orange, CA 92868-3298, USA. fsaremi@uci.edu
authors.forename: Farhood
authors.initials: F
authors.lastname: Saremi
authors.forename: Stephanie
authors.initials: S
authors.lastname: Channual
authors.forename: Swaminatha V
authors.initials: SV
authors.lastname: Gurudevan
authors.forename: Jagat
authors.initials: J
authors.lastname: Narula
authors.forename: Amir
authors.initials: A
authors.lastname: Abolhoda
mesh_terms: D000368:Aged; D020517:Atrial Appendage / Q000000981:diagnostic imaging*; D001281:Atrial Fibrillation / Q000150:complications* / Q000000981:diagnostic imaging*; D017023:Coronary Angiography / Q000379:methods*; D003328:Coronary Thrombosis / Q000150:complications* / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D014057:Tomography, X-Ray Computed / Q000379:methods*