title: ePLAR - The echocardiographic Pulmonary to Left Atrial Ratio - A novel non-invasive parameter to differentiate pre-capillary and post-capillary pulmonary hypertension.
abstract: BACKGROUND
  Right heart catheterisation is the gold-standard for differentiating pre-capillary pulmonary hypertension (high mean pulmonary artery pressure, normal pulmonary wedge pressure) from post-capillary physiology (elevated pulmonary wedge pressure). The new non-invasive parameter, ePLAR (echocardiographic Pulmonary to Left Atrial Ratio) is calculated from the maximum tricuspid regurgitation continuous wave Doppler velocity (m/s) divided by the transmitral E-wave:septal mitral annular Doppler Tissue Imaging e'-wave ratio (TRVmax/E:e').
  
  
  METHODS
  Pulmonary hypertension patients (mean pulmonary artery pressure>25mmHg, n=133, 66 male, average 65.0±16.8years) were classified by right heart catheterisation as pre-capillary or post-capillary [subdivided into isolated post-capillary (diastolic pulmonary gradient <7mmHg) or combined pre- and post-capillary cases]. The ePLAR values of these groups were compared to each other and to a population sample of 16,356 population reference echocardiograms.
  
  
  RESULTS
  ePLAR values for the normal reference population of 16,356 echocardiograms (age 56±16.6years) were 0.30±0.09m/s. Pre-capillary pulmonary hypertension patients (n=35, 26 male, PAPsys 63.9±16.6mmHg, PAPdiast 24.1±7.3mmHg, PAPmean 37.9±9.4mmHg, PCWP 10.6±2.7mmHg) had significantly higher ePLAR values than post-capillary cases (n=98, 40 male, PAPsys 59.9±17.6mmHg, PAPdiast 25.0±7.4mmHg, PAPmean 38.1±9.8mmHg, PCWP 23.5±6.4mmHg)-ePLAR 0.44±0.22m/s vs 0.20±0.11m/s (p<0.001). ePLAR values were significantly lower in isolated post-capillary pulmonary hypertension than in combined pre- and post-capillary cases (0.18±0.08m/s vs 0.28±0.18m/s, p<0.001).
  
  
  CONCLUSIONS
  ePLAR is a simple echocardiographic parameter which can accurately differentiate the smaller subset of patients with pre-capillary pulmonary hypertension from the more common post-capillary aetiology. The use of this easily obtained echocardiographic parameter has the potential to enhance non-invasive triage of patients for specific pulmonary vasodilator therapy.
authors.affiliation: The Prince Charles Hospital, Brisbane 4032, Australia; Heart Care Partners, Brisbane 4066, Australia; The Wesley Hospital, Brisbane 4066, Australia; University of Queensland, Brisbane 4068, Australia. Electronic address: gmscalia@gmail.com.
authors.forename: Gregory M
authors.initials: GM
authors.lastname: Scalia
authors.affiliation: University of Queensland, Brisbane 4068, Australia.
authors.forename: Isabel G
authors.initials: IG
authors.lastname: Scalia
authors.affiliation: Heart Care Partners, Brisbane 4066, Australia.
authors.forename: Rebecca
authors.initials: R
authors.lastname: Kierle
authors.affiliation: The Wesley Hospital, Brisbane 4066, Australia.
authors.forename: Rebekka
authors.initials: R
authors.lastname: Beaumont
authors.affiliation: Heart Care Partners, Brisbane 4066, Australia; The Wesley Hospital, Brisbane 4066, Australia.
authors.forename: David B
authors.initials: DB
authors.lastname: Cross
authors.affiliation: The Wesley Hospital, Brisbane 4066, Australia.
authors.forename: John
authors.initials: J
authors.lastname: Feenstra
authors.affiliation: The Prince Charles Hospital, Brisbane 4032, Australia; University of Queensland, Brisbane 4068, Australia.
authors.forename: Darryl J
authors.initials: DJ
authors.lastname: Burstow
authors.affiliation: The Prince Charles Hospital, Brisbane 4032, Australia; Heart Care Partners, Brisbane 4066, Australia; The Wesley Hospital, Brisbane 4066, Australia.
authors.forename: Benjamin T
authors.initials: BT
authors.lastname: Fitzgerald
authors.affiliation: The Prince Charles Hospital, Brisbane 4032, Australia.
authors.forename: David G
authors.initials: DG
authors.lastname: Platts
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D020517:Atrial Appendage / Q000000981:diagnostic imaging* / Q000503:physiopathology; D006328:Cardiac Catheterization; D015150:Echocardiography, Doppler / Q000379:methods*; D005260:Female; D006801:Humans; D006976:Hypertension, Pulmonary / Q000000981:diagnostic imaging* / Q000503:physiopathology / Q000628:therapy; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011669:Pulmonary Wedge Pressure
keywords: Cardiac Catheterization; Echocardiography; Pulmonary Hypertension