Doppler-Derived Pulmonary Arterial Compliance (PAC) Correlates with Invasively Measured PAC in Patients with Advanced Heart Failure and Reduced Ejection Fraction

Background Pulmonary arterial compliance (PAC), a marker of right ventricular (RV) afterload, represented as the ratio of stroke volume (SV) to pulmonary artery pulse pressure (PP), has been shown to be prognostic in heart failure populations. Prior work has shown that the ratio of right ventricular outflow tract pulsed-wave Doppler velocity time integral (RVOT-VTI; an echo-derived estimate of RV SV) and PA systolic pressure (PASP), correlates well with PAC obtained from invasive hemodynamics in patients with heart failure with preserved ejection fraction (HFpEF). We sought to explore this relationship in patients with heart failure with reduced ejection fraction (HFrEF) in a pre-left ventricular assist device (LVAD) cohort. Methods From a cohort of 196 patients with HFrEF awaiting LVAD implant at the Hospital of the University of Pennsylvania from 1/2008 to 2/2015, 72 patients underwent quantitative analysis of pre-implant echocardiogram by an independent reviewer (median days between echo and invasive hemodynamics were 3 [IQR 1-7]). We examined the relationship between RVOT-VTI/PASP with invasive PAC (calculated as SV/PP) using Pearson's rank coefficient and multivariate linear regression analysis. Results There were 42 patients (58%) with sufficient study quality to generate RVOT-VTI/PASP. The median RVOT-VTI/PASP was 0.16 cm/mmHg (IQR 0.11-0.23) and the median PAC was 1.61 ml/ mmHg (IQR 1.36-2.37). There was a modest but significant correlation between RVOT-VTI/PASP and PAC (r2 = 0.47; p=0.002) (Figure). In multivariate linear regression modeling, the relationship between RVOT-VTI/PASP and PAC was maintained (beta-coef 5.5, p=0.015) after adjusting for PCWP (beta-coef -0.016, p=0.5) and PVR (beta-coef -0.24, p=0.03). Conclusions In this small HFrEF cohort, RVOT-VTI/PASP, a proposed non-invasive metric of RV afterload that can be readily obtained on routine echocardiography, correlates with invasive PAC. Additional larger studies among patients with HFrEF are needed to determine if this relationship is maintained and is robust enough for the non-invasive estimation of PAC.