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Misclassification of Pulmonary Arterial Hypertension Due to Use of Pulmonary Capillary Wedge Pressure (PCWP) Rather Than Left-Ventricular End-Diastolic Pressure (LVEDP)

Scott Halpern

Darren Taichman


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Conference: 2008 International PHA Conference and Scientific Sessions

Release Date: 06.20.2008

Presentation Type: Abstracts

Halpern S.D., Taichman D.B.

University of Pennsylvania School of Medicine, Philadelphia, PA, USA

BACKGROUNDConsensus criteria for the diagnosis of pulmonary arterial hypertension (PAH) require exclusion of left atrial hypertension, which is typically done by documenting a PCWP of < 15mmHg. We hypothesized that use of LVEDP instead of PCWP would alter diagnostic classification.

METHODSAll patients undergoing simultaneous right-heart catheterization (RHC) and left-heart catheterization at our institution from 1998 – 2007 were evaluated. The proportions of patients meeting criteria for PAH vs. pulmonary venous hypertension

(PVH) were compared using the criteria of PCWP < 15 or LVEDP < 15. Hemodynamic variables were compared with those of patients undergoing isolated RHC to detect selection bias.

RESULTSAmong 13,317 patients undergoing simultaneous RHC and LHC, 5,213 (39.1%) had pulmonary hypertension (mean pulmonary artery pressure _ 25mmHg at rest). Among 4,666 patients (90%) with complete data, 521 (11.1%) met criteria for PAH using PCWP, but 50.2% of these would be classified as PVH if LVEDP were used instead. Among the 414 (8.9%) patients with PAH using LVEDP, 155 (37.4%) would have been classified as PVH using PCWP. Misclassification rates were 39.2% and 25.2%, respectively, among patients with pulmonary vascular resistance (PVR) _ 3 wood units. Patients undergoing combined LHC and RHC had lower PVR and higher PCWP than patients undergoing RHC alone.

CONCLUSIONSReliance on PCWP rather than LVEDP results in misclassification of nearly ½ of patients with pulmonary hypertension. Although selection bias was evident, the substantial misclassification even among those with elevated PVR validates the findings. Reliance on PCWP may result in the dangerous and/or cost-ineffective use of PAH medicines for those with PVH, or in the withholding of therapies from those who might benefit, and may bias the results of PAH therapeutic trials toward the null due to disease misclassification.

Misclassification of Pulmonary Arterial Hypertension Due to Use of Pulmonary Capillary Wedge Pressur