ePLAR - The echocardiographic Pulmonary to Left Atrial Ratio - A novel non-invasive parameter to differentiate pre-capillary and post-capillary pulmonary hypertension

Background: Right heart catheterisation is the gold-standard for differentiating pre-capillaty 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 > 25 mm Hg, n 133, 66 male, average 65.0 +/- 16.8 years) were classified by right heart catheterisation as pre-capillary or post-capillaiy [subdivided into isolated post-capillary (diastolic pulmonary gradient <7 mm Hg) 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 +/- 16.6 years) were 0.30 0.09 m/s. Pre-capillary pulmonary hypertension patients (n 35, 26 male, PAP(sys) 636 +/- 3.9 16.6 mm Hg, PAP(diast) 24.1 +/- 73 mm Hg PA(Pmean) 37.9 +/- 9.4 mm Hg, PCWP 106 +/- 2.7 mm Hg) had significantly higher ePLAR values than post-capillaty cases (n = 98,40 male, PAP(sys) 59.9 +/- 17.6 mm Hg, PAP(diast) 25.0 +/- 7A mm Hg, PAP(mean) 38.1 +/- 9.8 mm Hg, PCWP 23.5 +/- 6.4 mm Hg) - ePLAR 044 +/- 0.22 m/s vs 0.20 +/- 0.11 m/s (p < 0.001). ePLAR values were significantly lower in isolated post-capillaty pulmonary hypertension than in combined pre- and post-capillaty cases (0.18 +/- 0.08 m/s vs 028 +/- 0.18 m/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. (C) 2016 Elsevier Ireland Ltd. All rights reserved.