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

Portopulmonary Hypertension: A Review of the Current Literature

Portopulmonary hypertension is defined as the development of pulmonary arterial hypertension in the setting of portal hypertension with or without liver cirrhosis. Portal hypertension-associated haemodynamic changes, including hyperdynamic state, portosystemic shunts and splanchnic vasodilation, induce significant alterations in pulmonary vascular bed and play a pivotal role in the pathogenesis of the disease. If left untreated, portopulmonary hypertension results in progressive right heart failure, with a poor prognosis. Although Doppler echocardiography is the best initial screening tool for symptomatic patients and liver transplantation candidates, right heart catheterisation remains the gold standard for the diagnosis of the disease. Severe portopulmonary hypertension exerts a prohibitive risk to liver transplantation by conferring an elevated perioperative mortality risk. It is important for haemodynamic parameters to correspond with non-severe portopulmonary hypertension before patients can proceed with the liver transplantation. Small uncontrolled studies and a recent randomised controlled trial have reported promising results with vasodilatory therapies in clinical and haemodynamic improvement of patients, allowing a proportion of patients to undergo liver transplantation. In this review, the epidemiology, pathogenesis, diagnostic approach and management of portopulmonary hypertension are discussed. We also highlight fields of ongoing investigation pertinent to risk stratification and optimal patient selection to maximise long-term benefit from currently available treatments.

Doppler trans-thoracic echocardiography for detection of pulmonary hypertension in adults

BACKGROUND

Pulmonary hypertension (PH) is an important cause of morbidity and mortality, which leads to a substantial loss of exercise capacity. PH ultimately leads to right ventricular overload and subsequent heart failure and early death. Although early detection and treatment of PH are recommended, due to the limited responsiveness to therapy at late disease stages, many patients are diagnosed at a later stage of the disease because symptoms and signs of PH are nonspecific at earlier stages. While direct pressure measurement with right-heart catheterisation is the clinical reference standard for PH, it is not routinely used due to its invasiveness and complications. Trans-thoracic Doppler echocardiography is less invasive, less expensive, and widely available compared to right-heart catheterisation; it is therefore recommended that echocardiography be used as an initial diagnosis method in guidelines. However, several studies have questioned the accuracy of noninvasively measured pulmonary artery pressure. There is substantial uncertainty about the diagnostic accuracy of echocardiography for the diagnosis of PH.

OBJECTIVES

To determine the diagnostic accuracy of trans-thoracic Doppler echocardiography for detecting PH.

SEARCH METHODS

We searched MEDLINE, Embase, Web of Science Core Collection, ClinicalTrials.gov, World Health Organization International Clinical Trials Registry Platform from database inception to August 2021, reference lists of articles, and contacted study authors. We applied no restrictions on language or type of publication.

SELECTION CRITERIA

We included studies that evaluated the diagnostic accuracy of trans-thoracic Doppler echocardiography for detecting PH, where right-heart catheterisation was the reference standard. We excluded diagnostic case-control studies (two-gate design), studies where right-heart catheterisation was not the reference standard, and those in which the reference standard threshold differed from 25 mmHg. We also excluded studies that did not provide sufficient diagnostic test accuracy data (true-positive [TP], false-positive [FP], true-negative [TN], and false-negative [FN] values, based on the reference standard). We included studies that provided data from which we could extract TP, FP, TN, and FN values, based on the reference standard. Two authors independently screened and assessed the eligibility based on the titles and abstracts of records identified by the search. After the title and abstract screening, the full-text reports of all potentially eligible studies were obtained, and two authors independently assessed the eligibility of the full-text reports.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed the risk of bias and extracted data from each of the included studies. We contacted the authors of the included studies to obtain missing data. We assessed the methodological quality of studies using the Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) tool. We estimated a summary receiver operating characteristic (SROC) curve by fitting a hierarchical summary ROC (HSROC) non-linear mixed model. We explored sources of heterogeneity regarding types of PH, methods to estimate the right atrial pressure, and threshold of index test to diagnose PH. All analyses were performed using the Review Manager 5, SAS and STATA statistical software.

MAIN RESULTS

We included 17 studies (comprising 3656 adult patients) assessing the diagnostic accuracy of Doppler trans-thoracic echocardiography for the diagnosis of PH. The included studies were heterogeneous in terms of patient distribution of age, sex, WHO classification, setting, country, positivity threshold, and year of publication. The prevalence of PH reported in the included studies varied widely (from 6% to 88%). The threshold of index test for PH diagnosis varied widely (from 30 mmHg to 47 mmHg) and was not always prespecified. No study was assigned low risk of bias or low concern in each QUADAS-2 domain assessed. Poor reporting, especially in the index test and reference standard domains, hampered conclusive judgement about the risk of bias. There was little consistency in the thresholds used in the included studies; therefore, common thresholds contained very sparse data, which prevented us from calculating summary points of accuracy estimates. With a fixed specificity of 86% (the median specificity), the estimated sensitivity derived from the median value of specificity using HSROC model was 87% (95% confidence interval [CI]: 78% to 96%). Using a prevalence of PH of 68%, which was the median among the included studies conducted mainly in tertiary hospitals, diagnosing a cohort of 1000 adult patients under suspicion of PH would result in 88 patients being undiagnosed with PH (false negatives) and 275 patients would avoid unnecessary referral for a right-heart catheterisation (true negatives). In addition, 592 of 1000 patients would receive an appropriate and timely referral for a right-heart catheterisation (true positives), while 45 patients would be wrongly considered to have PH (false positives). Conversely, when we assumed low prevalence of PH (10%), as in the case of preoperative examinations for liver transplantation, the number of false negatives and false positives would be 13 and 126, respectively.

AUTHORS' CONCLUSIONS

Our evidence assessment of echocardiography for the diagnosis of PH in adult patients revealed several limitations. We were unable to determine the average sensitivity and specificity at any particular index test threshold and to explain the observed variability in results. The high heterogeneity of the collected data and the poor methodological quality would constrain the implementation of this result into clinical practice. Further studies relative to the accuracy of Doppler trans-thoracic echocardiography for the diagnosis of PH in adults, that apply a rigorous methodology for conducting diagnostic test accuracy studies, are needed.

Sensitivity and Specificity of Pulmonary Artery Pressure Measurement in Echocardiography and Correlation with Right Heart Catheterization

Objective

Echocardiography is helpful in assessment of pulmonary hemodynamic, however its correlation with Right heart catheterization (RHC) is conflicting. We conducted a study to evaluate sensitivity and specificity of pulmonary hemodynamic parameters measured in echocardiography. Furthermore its correlation with the values measured in RHC was assessed.

Method

Retrospective, cross-sectional study conducted at King Fahad medical City, Riyadh, Saudi Arabia. 95 adult patients referred for right heart catheterization were enrolled in the study. All the patients had echocardiography and RHC within one week of each other.

Result

Diabetes mellitus, hypertension and dyslipidemia were present among 55%, 66% and 41% of patients respectively. 85% of the study participants were diagnosed to have pulmonary hypertension and 79% of the study participants had postcapillary pulmonary hypertension. Sensitivity of pulmonary artery systolic pressure (PAPs), mean pulmonary artery pressure (PAPm) using PAPs and pulmonary artery acceleration velocity (PAcT) were 86%, 93% and 89% respectively. Correlation of PAPs, PAPm using PAPs and PAcT on echo with invasive hemodynamic in RHC were 0.56, 0.43 and 0.24 respectively. Among patients with moderate to severe Tricuspid Regurgitation (TR) and tricuspid annular plane systolic excursion (TAPSE) <1.5cm correlation of PAPs, PAPm using PAPs and PAcT on echocardiography with right heart catheterization were 0.31, 0.24 and 0.42 respectively.

Conclusion

Echocardiographic assessment of PAPs and PAPm has high sensitivity and weak to moderate correlation with hemodynamic data in RHC. PAPs measurement on echocardiogram has best correlation with invasive measurement followed by PAPm measurement using PAPs. Among patients with moderate to severe TR and TAPSE <1.5cm PAPm measurement using PAcT has better correlation than using PAPs.

Multimodal Ultrasound Model Based on the Left Gastric Vein in B-Viral Cirrhosis: Noninvasive Prediction of Esophageal Varices

OBJECTIVES:

To establish and verify a simple noninvasive model based on the left gastric vein (LGV) to predict the grade of esophageal varices (EV) and high-risk EV (HEV), to facilitate clinical follow-up and timely treatment.

METHODS:

We enrolled 320 patients with B-viral cirrhosis. All patients underwent endoscopy, laboratory tests, liver and spleen stiffness (SS), and ultrasonography. HEV were analyzed using the χ² test/t test and logistic regression in the univariate and multivariate analyses, respectively. EV grades were analyzed using the variance/rank-sum test and logistic regression. A prediction model was derived from the multivariate predictors.

RESULTS:

In the training set, multivariate analysis showed that the independent factors of different EV grades were SS, LGV diameter, and platelet count (PLT). We developed the LGV diameter-SS to PLT ratio index (LSPI) and LGV diameter/PLT models without SS. The area under the receiver operating characteristic curve of the LSPI for diagnosis of small EV, medium EV, large EV, and HEV was 0.897, 0.899, 0.853, and 0.954, respectively, and that of the LGV/PLT was 0.882, 0.890, 0.837, and 0.942, respectively. For the diagnosis of HEV, the negative predictive value was 94.07% when LSPI < 19.8 and the positive predictive value was 91.49% when LSPI > 23.0. The negative predictive value was 95.92% when LGV/PLT < 5.15, and the positive predictive value was 86.27% when LGV/PLT > 7.40. The predicted values showed similar accuracy in the validation set.

DISCUSSION:

Under appropriate conditions, the LSPI was an accurate method to detect the grade of EV and HEV. Alternatively, the LGV/PLT may also be useful in diagnosing the varices when condition limited.

Validity of echocardiographic tricuspid regurgitation gradient to screen for new definition of pulmonary hypertension

BACKGROUND

Currently an echocardiographic threshold for the tricuspid regurgitation gradient (TRG) of > 31 mmHg is recommended for screening for pulmonary hypertension (PH). Invasively diagnosed PH was recently redefined as mean pulmonary arterial pressure (mPAP) > 20 mmHg instead of ≥ 25 mmHg. We investigated the ability of TRG to screen for the new PH-definition.

METHODS

Retrospective assessment of echocardiography and right heart catheterisation data from 1572 patients entering the Giessen PH-Registry during 2008-2018. Accuracy of different TRG thresholds and other echocardiographic parameters was evaluated using receiver operating characteristic curves.

FINDINGS

1264 patients fulfilled the new PH-definition. Positive (PPV) and negative predictive values and accuracy of TRG > 46 mmHg were 95%, 39%, and 73%, respectively, for the new PH-definition. Lowering the TRG cut-off to 31 mmHg and below worsened PPV to ≤ 89%. The PPV of TRG for pre-capillary PH (mPAP > 20 mmHg and pulmonary vascular resistance ≥ 3 Wood Units) was ≤ 85%. In patients with TRG ≤ 46 mmHg, tricuspid annular plane systolic excursion/TRG and TRG/right ventricular outflow tract acceleration time were superior to TRG in screening for newly defined pre-capillary PH.

INTERPRETATION

In patients with suspected PH referred to a tertiary care centre, the PPV of TRG to meet the new PH-definition depended strongly on the TRG cut-off used. Our data do not support lowering the TRG cut-off. Combining TRG with other echocardiographic parameters might improve the validity of echocardiographic screening for PH.

Performance of echocardiography for detection of portopulmonary hypertension among liver transplant candidates: Meta-analysis

BACKGROUND

Evaluation of pulmonary arterial pressure is crucial among cirrhotic patients, considering that moderate portopulmonary hypertension (POPH) is a contraindication for liver transplantation. Although right heart catheterization (RHC) is the most accurate method to diagnose POPH, it is invasive.

OBJECTIVE

The aim of the study is to evaluate the performance of echocardiography in detecting POPH in liver transplant candidates.

METHODS

A Literature search was performed, and pooled sensitivity, specificity, positive likelihood ratio (LR), negative LR, and area under the summary receiver operating curve (AUC) were calculated. Subgroup analyses were performed based on different cutoff values for echocardiography and diagnostic criteria of RHC.

RESULTS

Sensitivity, specificity, positive LR, negative LR, and AUC of echocardiography for detection of POPH were 0.86 (0.74, 0.94), 0.87 (0.84, 0.90), 7.17 (3.59, 14.31), 0.22 (0.13, 0.38), and 0.807 while they were 0.82 (0.74, 0.89), 0.81 (0.78, 0.84), 117.75 (16.03, 865.08), 0.28 (0.16, 0.50), and 0.876for detection of moderate POPH, respectively. Performance of echocardiography was not significantly different in the subgroup analyses of stringency of POPH criteria and pulmonary arterial systolic pressure (ePASP) cutoffs.

CONCLUSIONS

Our meta-analysis supports utilization of echocardiography for screening of POPH. However, RHC remains essential in highly suspicious cases. Echocardiographic data other than ePASP should be evaluated in future studies.

Role of echocardiography in screening for portopulmonary hypertension in liver transplant candidates: a meta-analysis

Objectives

To demonstrate the screening value of echocardiography for portopulmonary hypertension (POPH) in liver transplant candidates.

Design

Systematic review and meta-analysis.

Background

POPH is a complication of end-stage liver disease that adversely affects the outcome of orthotopic liver transplant. There are no specific symptoms in the early stage of POPH. POPH reduce the survival rate of patients with end-stage liver disease specially if they are not diagnosed. Therefore, early detection may improve prognosis. The objective of this study is to explore the screening value of echocardiography on liver transplant candidates for screening of POPH compared to right heart catheterization (RHC).

Method

PubMed, EMBASE and the Cochrane Library were searched by two independent reviewers for potentially eligible studies published up to 30 June 2019 to retrieve data based on per-patient analysis. STATA, Meta-DiSc, and RevMan were applied to perform this meta-analysis.

Results

Our search yielded 1576 studies, of which 11 satisfied the inclusion criteria. The pooled sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR) and area under the summary receiver operating characteristic (SROC) curve (AUC) of echocardiography for POPH were 0.85 (95% CI [0.65–0.94]), 0.83 (95% CI [0.73–0.90]), 4.99 (95% CI [3.03–8.21]), 0.19 (95% CI [0.07–0.46]), and 0.91 (95% CI [0.88–0.93]), respectively. Deeks’ funnel plot did not indicate the existence of publication bias (P = 0.66).

Conclusions

Echocardiography, a noninvasive modality, provides superior screening for POPH, but the diagnosis of POPH still requires RHC. PROSPERO registration number CRD42019144589.

Diagnostic accuracy of transthoracic echocardiography for pulmonary hypertension: a systematic review and meta-analysis

OBJECTIVE

To evaluate the diagnostic accuracy of transthoracic echocardiography (TTE) in patients with pulmonary hypertension (PH).

DESIGN

Systematic review and meta-analysis.

DATA SOURCES AND ELIGIBILITY CRITERIA

Embase, Cochrane Library for clinical trials, PubMed and Web of Science were used to search studies from inception to 19 June, 2019. Studies using both TTE and right heart catheterisation (RHC) to diagnose PH were included.

MAIN RESULTS

A total of 27 studies involving 4386 subjects were considered as eligible for analysis. TTE had a pooled sensitivity of 85%, a pooled specificity of 74%, a pooled positive likelihood ratio of 3.2, a pooled negative likelihood ratio of 0.20, a pooled diagnostic OR of 16 and finally an area under the summary receiver operating characteristic curve of 0.88. The subgroup with the shortest time interval between TTE and RHC had the best diagnostic effect, with sensitivity, specificity and area under the curve (AUC) of 88%, 90% and 0.94, respectively. TTE had lower sensitivity (81%), specificity (61%) and AUC (0.73) in the subgroup of patients with definite lung diseases. Subgroup analysis also showed that different thresholds of TTE resulted in a different diagnostic performance in the diagnosis of PH.

CONCLUSION

TTE has a clinical value in diagnosing PH, although it cannot yet replace RHC considered as the gold standard. The accuracy of TTE may be improved by shortening the time interval between TTE and RHC and by developing an appropriate threshold. TTE may not be suitable to assess pulmonary arterial pressure in patients with pulmonary diseases.

PROSPERO REGISTRATION NUMBER

PROSPERO CRD42019123289.

Clinical Retrospective Analysis of Interstitial Lung Disease Patients Associated with Pulmonary Hypertension

BACKGROUND Pulmonary hypertension is a common complication of interstitial lung disease. This study was conducted to retrospectively analyze the incidence of pulmonary hypertension among interstitial lung disease patients and the correlation between systolic pulmonary artery pressure (PASP) and pulmonary functions. We also intended to investigate whether antinuclear antibody (ANA) could be an effective indicator of pulmonary hypertension. MATERIAL AND METHODS There were 182 patients diagnosed with interstitial lung disease through high-resolution computed tomography (HRCT). Pulmonary hypertension was defined as an increase of mean pulmonary arterial pressure (PAPm) ≥25 mmHg (~PASP ≥40 mmHg) at rest. Severe pulmonary hypertension was defined as PAPm ≥35 mmHg. There were 104 cases including in this study. There were 67 cases from the ANA positive (ANA+) group and 37 cases from the ANA negative (ANA-) group. All study patients had pulmonary function tests, which included the measurements of maximal voluntary ventilation (MVV), residual volume (RV), total lung capacity (TLC), forced expiratory volume (FVC), vital capacity (VC), and diffusing capacity of the lungs for carbon monoxide (DLCO). RESULTS The pulmonary hypertension incidence in the study cohort was 25%, and the severe pulmonary hypertension incidence was 6.48%. The incidence of pulmonary hypertension in ANA+ cases was 22.22%. The incidence of pulmonary hypertension in the ANA- cases was 32.14%. The lung function test results showed moderate relationships between DLCO, FVC%, VC%, and PASP; no relationship between MVV, FEV1/FVC%, RV/TLC, and PASP; minimum relationship between FVC%, VC%, and PASP in the ANA+ group; and moderate relationship between FVC%, VC%, and PASP in the ANA- group. CONCLUSIONS Pulmonary hypertension occurred in 25% of the 182 interstitial lung disease patients and was negatively associated with deteriorated lung functions (specifically VC%, FVC%, and DLCO parameters). ANA level was not associated with the prognosis of pulmonary hypertension of patients with interstitial lung disease, and it did not significantly affect the correlation between PASP and pulmonary functions. Thus, ANA level did not seem to be a necessary indicator of pulmonary hypertension, and a more effective treatment method for pulmonary hypertension of patients with interstitial lung disease is urgently needed.