title: Clinical validity of a normal pulmonary angiogram in patients with suspected pulmonary embolism--a critical review.
abstract: OBJECTIVE
  To determine the validity of a normal pulmonary angiogram in the exclusion of pulmonary embolism (PE), based on the safety of withholding anticoagulant therapy in patients with a normal pulmonary angiogram.
  
  
  METHODS
  A review of English reports published between 1965 and April 1999 was carried out. Eligible articles described prospective studies in patients with suspected PE and a normal pulmonary angiogram, who remained untreated and were followed-up for a minimum of 3 months. Articles were evaluated by two authors, using pre-defined criteria for strength of design. End points consisted of fatal and non-fatal recurrent thromboembolic events. A sensitivity analysis was performed, by removing one study at a time from the overall results and by comparing pre- and post-1990 publications.
  
  
  RESULTS
  Among 1050 patients in eight articles included in the analysis, recurrent thromboembolic events were described in 18 patients (1.7% 95% CI: 1.0-2.7%). These were fatal in three patients (0.3% 95% CI: 0.02-0.7%). The recurrence rate of PE decreased from 2.9% (95% CI: 1.4-6.8%) before 1990 to 1.1% (95% CI: 0.5-2.2%) after 1990.
  
  
  CONCLUSIONS
  It would appear that the ability to exclude PE by angiography has improved over the years, as indicated by recurrence rate of PE. The low recurrence rate of PE supports the validity of a normal pulmonary angiogram for the exclusion of PE.
authors.affiliation: Section of Academic Radiology, Royal Hallamshire Hospital, Sheffield, UK. e.vanbeek@sheffield.ac.uk
authors.forename: E J
authors.initials: EJ
authors.lastname: van Beek
authors.forename: E M
authors.initials: EM
authors.lastname: Brouwerst
authors.forename: B
authors.initials: B
authors.lastname: Song
authors.forename: P D
authors.initials: PD
authors.lastname: Stein
authors.forename: M
authors.initials: M
authors.lastname: Oudkerk
mesh_terms: D000925:Anticoagulants / Q000008:administration & dosage; D006801:Humans; D011446:Prospective Studies; D011651:Pulmonary Artery / Q000000981:diagnostic imaging*; D011655:Pulmonary Embolism / Q000000981:diagnostic imaging* / Q000517:prevention & control; D011859:Radiography; D012008:Recurrence; D012680:Sensitivity and Specificity
chemical_list: D000925:Anticoagulants