Transpulmonary Gradient as a Predictor of Outcomes after Heart Transplantation

Abstract

Purpose Transpulmonary pressure gradient (TPG) – the difference between mean pulmonary arterial pressure and pulmonary capillary wedge pressure – is increased in left-heart conditions associated pulmonary venous congestion. This is a risk factor for right heart failure after heart transplantation (HT). We assessed the clinical significance of TPG by assessing its role in predicting hospital length of stay (LOS) and survival after HT. Methods We queried the UNOS database from 1987 to 2017, and included adults with complete TPG data who underwent HT. Re-transplant patients were excluded. Eligible patients were divided into low (<=15) and high (>15) TPG. We compared demographics, mean hospital LOS, and extended LOS (LOS >14 days) with Wilcoxon and Chi-square-test. Survival time, as well as 5-year and 10-year survival was evaluated with Kaplan-Meir and compared between groups with Log-rank tests. Results Our sample consisted of 38,243 patients. Low and high TPG groups varied with respect to certain demographics. Median survival was higher in the low TPG group (145 vs 133 months in high TPG group, p<0.0001). Patients in the low TPG group also had higher 5-year (75.8% vs 72.4%, p<0.0001) and 10-year (57.7% vs 53.9%, p<0.0001) survival. Mean hospital LOS (20.1 vs 21.8, p<0.0001) and extended LOS were lower in the low TPG group (53.9% vs 57.2%, p<0.0005). Conclusion High TPG was associated with a lower survival and a longer hospital LOS after HT. Future work should expand on these findings and explore factors such as whether survival and LOS differences relate to post-transplant right ventricular failure, which requires prolonged inotropic support and can also affect overall survival. Transpulmonary pressure gradient (TPG) – the difference between mean pulmonary arterial pressure and pulmonary capillary wedge pressure – is increased in left-heart conditions associated pulmonary venous congestion. This is a risk factor for right heart failure after heart transplantation (HT). We assessed the clinical significance of TPG by assessing its role in predicting hospital length of stay (LOS) and survival after HT. We queried the UNOS database from 1987 to 2017, and included adults with complete TPG data who underwent HT. Re-transplant patients were excluded. Eligible patients were divided into low (<=15) and high (>15) TPG. We compared demographics, mean hospital LOS, and extended LOS (LOS >14 days) with Wilcoxon and Chi-square-test. Survival time, as well as 5-year and 10-year survival was evaluated with Kaplan-Meir and compared between groups with Log-rank tests. Our sample consisted of 38,243 patients. Low and high TPG groups varied with respect to certain demographics. Median survival was higher in the low TPG group (145 vs 133 months in high TPG group, p<0.0001). Patients in the low TPG group also had higher 5-year (75.8% vs 72.4%, p<0.0001) and 10-year (57.7% vs 53.9%, p<0.0001) survival. Mean hospital LOS (20.1 vs 21.8, p<0.0001) and extended LOS were lower in the low TPG group (53.9% vs 57.2%, p<0.0005). High TPG was associated with a lower survival and a longer hospital LOS after HT. Future work should expand on these findings and explore factors such as whether survival and LOS differences relate to post-transplant right ventricular failure, which requires prolonged inotropic support and can also affect overall survival.