Interplay of Pulmonary Artery Systolic Pressure and Pulmonary Vascular Resistance on Post-Transplant Survival

Abstract

Pulmonary vascular resistance (PVR) >3 WU is a relative contraindication to heart transplant. However, previous analyses have not shown an association between PVR and post-transplant survival. Pulmonary artery systolic pressure (PASP) >50 mmHg has been associated with worse post-transplant survival. We explored the interplay between PVR and PASP and their effect on post-transplant survival independently and in conjunction with each other to understand their interaction on predicting post-transplant survival. Adults (≥18 years) who underwent heart transplantation in the United States between 2010 and 2015 were retrospectively identified from the United Network for Organ Sharing registry. Pre-transplant PASP was classified as low (PASP <50 mmHg) and high (PASP >50 mmHg). Pre -transplant PVR was divided into low (PVR <3 WU) and high (PVR >3 WU). The effects of PASP and PVR were studied on post-transplant 1-year survival and long-term survival independently and in combination using cox regression. Study included 12658 transplant recipients (mean age 53.11 years; 73.6% male). During a mean follow-up of 3 years, there were 2158 (17%) deaths. Mean PASP in high and low PASP groups were 63 mmHg, and 35 mmHg and mean PVR in high and low PVR group were 4.53 WU, and 1.63 WU respectively. PVR did not have any independent effect on 1-year mortality (HR: 1.07, CI: 0.95 - 1.20, p : 0.25) or overall survival (HR: 1.06, CI: 0.97 - 1.15, p : 0.175). High PASP independently predicted worse 1-year mortality (HR: 1.14, CI: 1.01 - 1.29, p : 0.02) but not overall survival (HR: 1.08, CI: 0.99-1.19, p : 0.05). Elevated PASP in combination with high PVR predicted worse 1-year survival (HR: 1.32, CI: 1.11 - 1.59, p : 0.002) and overall survival (hazard ratio 1.17, CI 1.03-1.34, p: 0.015) in cox regression analysis. High PASP did not predict worse 1-year (HR: 0.98, CI: 0.83 - 1.17, p : 0.9) and overall mortality (HR: 1.007, CI: 0.89 - 1.13, p : 0.9) in subgroup of patients with PVR <3 WU. Multivariate analysis yielded similar results. In patients with PVR> 3 WU elevated pre-transplant PASP (>50mmHg) is associated with a decrease in one year and overall survival when compared to patients low PASP. In patients with PVR<3 WU PASP is not a predictor of post-transplant survival. This suggest that PASP (>50 mmHg) in conjunction with PVR ≥ 3 WU defines a high-risk subgroup.