Right Ventricular Outflow Tract Doppler Envelope Notching Predicts Pulmonary Hypertension and Outcomes in Lung Transplant Candidates

Abstract

Hemodynamic variables have prognostic implications in lung transplant (LT) candidates, but it is unclear which echocardiographic (TTE) parameters predict outcomes in this population. We retrospectively studied 149 LT candidates who underwent TTE and right heart catheterization (RHC) 2007-2014, with follow-up to 2018. TTE parameters included the pulmonary artery systolic pressure (PASP), pulmonary vascular resistance (ePVR), and notching of the right ventricular outflow tract Doppler flow velocity envelope (FVERVOT), which has been shown to correlate with invasive PVR. We used Kaplan-Meier survival analysis and multivariate Cox proportional-hazards regression to analyze the relationship between TTE parameters and pre- and post-LT outcomes. Most patients were from Lung Allocation Groups A (25%) and D (66%). Mean age was 55±12 years, 60% were men. The PASP was identifiable in 135 patients. FVERVOT was interpretable in all patients, and notching was present in 46 patients. Mid-systolic notching of the FVERVOT had perfect specificity for prediction of pulmonary hypertension (13% sensitivity). Of 149 patients, 127 underwent LT; there were 9 deaths prior to LT and 36 deaths after LT. Median post-transplant follow-up was 5.5 (IQR 3.7-7.0) years. Pre-LT, patients with FVERVOT notching had shorter transplant-free survival (Figure 1a) and increased likelihood of undergoing transplantation (HR 1.87, 95%CI 1.25-2.80). Neither the PASP nor ePVR were predictive of transplantation. Post-LT, none of the TTE parameters predicted mortality, although patients with notching trended towards worse survival (Figure 1b) and increased mortality (HR 1.88, 95%CI 0.91-3.91, p=0.09). Unlike the PASP or ePVR, FVERVOT notching identified a group of LT candidates who had PH and were likely to undergo transplantation. Assessment of FVERVOT notching may help clinicians determine when repeat RHC is indicated to optimize the lung allocation score.