Correlation between Echocardiographic Pulmonary Artery Pressure Estimates and Right Heart Catheterization Measurement in Liver Transplant Candidates

Abstract

Background: Patients undergoing liver transplant have worse outcomes in the presence of pulmonary hypertension. Correlation between echocardiography and catheterization derived pressures in this population is not well studied. Our study's aim is to show the relationship between pulmonary artery systolic pressure derived from transthoracic echo (ePASP) with pulmonary artery systolic pressure measured during right heart catheterization (cPASP).

Methods: Single center retrospective study, patients being evaluated for liver transplant (n = 31) who had an interpretable Doppler signal for ePASP and had right heart catheterization (RHC) measurements within 3 months constituted the study group. Control group (n = 49) consisted of patients who did not have liver disease.

Results: There was modest correlation between ePASP and cPASP (R = 0.58, p < 0.001) in LT candidates (n = 31) compared with the control group (R = 0.74, p < 0.001, n = 49). The 95% limits of agreement by Bland-Altman analysis ranged from +33.6 mmHg to -21.7 mmHg. Using receiver operating characteristic analysis, ePASP cut-off > 47 mmHg was 59% sensitive and 78% specific to diagnose pulmonary artery (PA) hypertension (mean PA pressure > 25 mmHg) in the LT candidates, while a similar cutoff performed well in the control group (cutoff > 43 mmHg, n = 47, 91% sensitive, 100% specific).

Conclusions: Compared with other disease states, ePASP correlates modestly with cPASP in patients with advanced liver disease. A higher ePASP cutoff should be used to screen for pulmonary hypertension. A multi-center prospective study with simultaneous transthoracic echocardiography and RHC measurements is required to determine the best cut-off in this population.

Keywords: Cirrhosis; Echocardiography; Liver transplant; Portopulmonary hypertension; Pulmonary hypertension.

Figure 1. Study population flow chart.

Figure 2. (A) cPASP vs. ePASP in liver transplant candidates shows modest correlation (r = 0.58, p = 0.006). (B) cPASP vs. ePASP in control group shows stronger correlation (r = 0.74, p < 0.001). cPASP: pulmonary artery systolic pressure measured during right heart catheterization, ePASP: pulmonary artery systolic pressure derived from transthoracic echocardiography.

Figure 3. (A) Bland Altman plot analysis of liver transplant candidates reveals bias for ePASP-cPASP of 5.9 mmHg with 95% limits of agreement ranging from +33.6 to -21.7 mmHg. (B) Bland Altman plot analysis of control group, revealing bias for ePASP-cPASP of -0.1 mmHg with 95% limits of agreement ranging from +30.1 and -30.4 mmHg. cPASP: pulmonary artery systolic pressure measured during right heart catheterization, ePASP: pulmonary artery systolic pressure derived from transthoracic echocardiography.

Figure 4. ROC analysis in liver transplant candidates demonstrate that ePASP cut-off > 47 mmHg was only 59% sensitive and 78% specific; area under curve = 0.7, positive predictive value = 73.3%, negative predictive value = 61%. ePASP: pulmonary artery systolic pressure derived from transthoracic echocardiography, ROC: receiver operating characteristic.