Portopulmonary hypertension in liver transplant candidates: Echocardiographic screening, prevalence, and long-term outcomes

Abstract

Introduction and Objectives: Portopulmonary hypertension (PoPH) represents a significant pulmonary vascular complication in patients with portal hypertension, substantially increasing perioperative mortality during liver transplantation (LT). While systematic transthoracic echocardiographic (TTE) screening has become standard practice, optimal diagnostic thresholds and prevalence data across diverse populations remain incompletely characterized. This investigation sought to determine the prevalence of PoPH among LT candidates at a tertiary hepatology center, comprehensively characterize the clinical and hemodynamic profiles of affected patients, and evaluate the diagnostic efficacy of TTE screening protocols. Patients or Materials and Methods: We conducted a comprehensive retrospective analysis of 422 consecutive LT candidates with portal hypertension evaluated at our tertiary center between 2007–2017. All patients underwent systematic TTE, with right heart catheterization (RHC) performed when right ventricular systolic pressure (RVSP) exceeded 40 mmHg or when indirect pulmonary hypertension indicators were present. PoPH was defined according to currently established hemodynamic criteria: mean pulmonary arterial pressure >20 mmHg, pulmonary vascular resistance >2 Wood units, and pulmonary arterial wedge pressure ≤15 mmHg. Results: Among 422 patients (mean age 52.9 ± 12.3 years, 67.5 % male), chronic hepatitis B predominated (35.1 %). Fifty-two patients underwent RHC, with twenty (4.74 % of total cohort) receiving definitive PoPH diagnosis. PoPH patients demonstrated significantly higher pulmonary vascular resistance (3.51 ± 1.90 vs 1.25 ± 1.02 Wood units, p < 0.001), and transpulmonary gradient (18.05 ± 9.28 vs 9.56 ± 8.43 mmHg, p = 0.001), while reduced pulmonary arterial wedge pressure (9.45 ± 1.73 vs 13.53 ± 4.81 mmHg, p < 0.001), cardiac output (5.21 ± 0.95 vs 7.57 ± 1.38 L/min, p < 0.001), and cardiac index (2.97 ± 0.98 vs 4.15 ± 0.85 L/min/m², p = 0.023) compared to non-PoPH patients. Targeted pulmonary vasodilator therapy was initiated in three patients with mean pulmonary arterial pressure ≥35 mmHg, with two severe cases successfully bridged to LT following demonstrable hemodynamic improvement. The 40 mmHg TTE threshold demonstrated robust diagnostic performance characteristics: 95.0 % sensitivity, 93.5 % specificity, 42.2 % positive predictive value, 99.7 % negative predictive value, with positive and negative likelihood ratios of 14.7 and 0.05, respectively. Conclusions: PoPH affects 4.74 % of LT candidates with portal hypertension using contemporary diagnostic criteria. Systematic TTE screening employing a 40 mmHg threshold for RVSP effectively identifies patients requiring further hemodynamic assessment, with exceptional negative predictive value enabling confident exclusion of clinically significant disease while minimizing unnecessary procedures. Early recognition coupled with targeted therapy successfully bridges selected patients to LT with excellent long-term outcomes.