title: Intrapulmonary shunt is a potentially unrecognized cause of ischemic stroke and transient ischemic attack.
abstract: BACKGROUND
  Ischemic stroke is a major cause of mortality and disability. Transient ischemic attack (TIA) is a harbinger of stroke. The etiology of stroke in as many as 40% of patients remains undetermined after extensive evaluation. It was hypothesized that intrapulmonary shunt is a potential facilitator of cerebrovascular accident (CVA) or TIA.
  
  
  METHODS
  Patients undergoing clinically indicated transesophageal echocardiography were prospectively enrolled. Comprehensive multiplane transesophageal echocardiographic imaging was performed and saline contrast done to assess for intrapulmonary shunt and patent foramen ovale.
  
  
  RESULTS
  Three hundred twenty-one patients with either nonhemorrhagic CVA (n = 262) or TIA (n = 59) made up the stroke group. Three hundred twenty-one age-matched and gender-matched patients made up the control group. Intrapulmonary shunt occurred more frequently in the stroke group (72 of 321) compared with the control group (32 of 321) (22% vs 10%, P < .0001). Intrapulmonary shunt was an independent predictor of CVA and/or TIA (odds ratio, 2.6; P < .0001). In subjects with cryptogenic CVA or TIA (n = 71), intrapulmonary shunt occurred more frequently (25 of 71) than in the control group (5 of 71) (35% vs 7%, P < .0001). Intrapulmonary shunt was an independent multivariate predictor of CVA or TIA in patients with cryptogenic CVA or TIA (odds ratio, 6.3; P < .005).
  
  
  CONCLUSIONS
  These results suggest that intrapulmonary shunt is a potentially unrecognized facilitator of CVA and TIA, especially in patients with cryptogenic CVA and TIA. Future studies assessing the prognostic significance of intrapulmonary shunt on cerebral vascular event recurrence rates in patients after initial CVA or TIA would be of great interest.
authors.affiliation: Department of Medicine, Division of Cardiovascular Medicine, University of Louisville, Louisville, Kentucky, USA.
authors.forename: Mohannad Y
authors.initials: MY
authors.lastname: Abushora
authors.forename: Nirmanmoh
authors.initials: N
authors.lastname: Bhatia
authors.forename: Ziad
authors.initials: Z
authors.lastname: Alnabki
authors.forename: Mohan
authors.initials: M
authors.lastname: Shenoy
authors.forename: Motaz
authors.initials: M
authors.lastname: Alshaher
authors.forename: Marcus F
authors.initials: MF
authors.lastname: Stoddard
mesh_terms: D015897:Comorbidity; D015150:Echocardiography, Doppler; D017548:Echocardiography, Transesophageal; D005260:Female; D054092:Foramen Ovale, Patent / Q000150:complications* / Q000000981:diagnostic imaging*; D006801:Humans; D002546:Ischemic Attack, Transient / Q000209:etiology*; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D018709:Statistics, Nonparametric; D020521:Stroke / Q000209:etiology*