title: Current practice for determining pulmonary capillary wedge pressure predisposes to serious errors in the classification of patients with pulmonary hypertension.
abstract: BACKGROUND
  Accurate measurement of left ventricular filling pressure is important to distinguish between category 1 pulmonary arterial hypertension (PAH) and category 2 pulmonary hypertension (PH) from left heart diseases (PH-HFpEF). We hypothesized that the common practice of relying on the digitized mean pulmonary capillary wedge pressure (PCWP-digital) results in erroneous recordings, whereas end-expiratory PCWP measurements (PCWP-end Exp) provide a reliable surrogate measurement for end-expiratory left ventricular end-diastolic pressure (LVEDP-end Exp-end Exp).
  
  
  METHODS
  We prospectively performed left and right cardiac catheterization on 61 patients referred for evaluation of PH and compared the LVEDP-end Exp to end-expiration to the (a) PCWP-end Exp and (b) PCWP-digital.
  
  
  RESULTS
  The PCWP-end Exp was a more reliable reflection of LVEDP-end Exp (mean 13.2 mm Hg vs 12.4 mm Hg; P, nonsignificant) than PCWP-digital (mean 8.0 mm Hg vs 12.4 mm Hg, P < .05). Bland-Altman analysis of PCWP-digital and LVEDP-end Exp revealed a mean bias of -4.4 mm Hg with 95% limits of agreement of -11.3 to 2.5 mm Hg. Bland-Altman analysis of PCWP-end Exp and LVEDP-end Exp revealed a mean bias of 0.9 mm Hg with 95% limits of agreement of -5.2 to 6.9 mm Hg. If PCWP-digital were used to define LVEDP-end Exp, 14 (27%) of 52 patients would have been misclassified as having PAH rather than PH-HFpEF. Patients with obesity and hypoxia were particularly more likely to be misclassified as PAH instead of PH-HFpEF if PCWP-digital was used to define LVEDP-end Exp (odds ratio 8.1, 95% CI 1.644-40.04, P = .01).
  
  
  CONCLUSIONS
  The common practice of using PCWP-digital instead of PCWP-end Exp results in a significant underestimation of LVEDP-end Exp. In our study, this translated to nearly 30% of patients being misclassified as having PAH rather than PH from HFpEF.
authors.affiliation: Section of Cardiology, Department of Medicine, University of Chicago, Chicago, IL, USA. john.ryan@uchospitals.edu
authors.forename: John J
authors.initials: JJ
authors.lastname: Ryan
authors.forename: Jonathan D
authors.initials: JD
authors.lastname: Rich
authors.forename: Thejasvi
authors.initials: T
authors.lastname: Thiruvoipati
authors.forename: Rajiv
authors.initials: R
authors.lastname: Swamy
authors.forename: Gene H
authors.initials: GH
authors.lastname: Kim
authors.forename: Stuart
authors.initials: S
authors.lastname: Rich
mesh_terms: D000368:Aged; D006328:Cardiac Catheterization; D005260:Female; D006439:Hemodynamics; D006801:Humans; D006976:Hypertension, Pulmonary / Q000145:classification* / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011669:Pulmonary Wedge Pressure; D015203:Reproducibility of Results