The Lung Allocation Score Remains Inequitable for Patients with Pulmonary Arterial Hypertension, Even after the 2015 Revision

Optimizing patient outcomes in interstitial lung disease through pre- and post-transplant management strategies

Interstitial lung diseases (ILD) encompass a diverse group of over 200 chronic pulmonary disorders characterized by varying degrees of inflammation and fibrosis, which can lead to severe respiratory impairment. Lung transplantation offers a crucial therapeutic option for patients with advanced ILD, extending survival and improving quality of life. This review explores optimal management strategies in both the pre- and post-transplant phases to enhance patient outcomes. Comprehensive pre-transplant evaluation, including pulmonary function testing, imaging, and comorbidity assessment, is critical for determining transplant eligibility and timing. Post-transplant care must focus on preventing complications such as primary graft dysfunction and chronic lung allograft dysfunction, managed through tailored immunosuppression and proactive monitoring. Recent advancements in diagnostic techniques and therapeutic approaches, including emerging technologies like ex vivo lung perfusion and precision medicine, promise to further improve outcomes. The ultimate goal is to establish an evidence-based, multidisciplinary framework for optimizing ILD management and lung transplantation.

[Indications for Lung Transplantation - Updates Since the Last ISHLT Recommendations]

Lung transplantation has evolved continuously since its first successful procedures in the 1960 s. The current guidelines from the International Society for Heart and Lung Transplantation (ISHLT) emphasise increasingly individualised patient assessment, which, in addition to the underlying lung disease, considers factors such as comorbidities, frailty, age, and social aspects. The expanded indications for lung transplantation are reflected in the refined risk assessment, which particularly includes patients with advanced chronic obstructive pulmonary disease (COPD), idiopathic pulmonary fibrosis (IPF), and pulmonary arterial hypertension (PAH). Furthermore, the criteria for patients with a history of cancer and those with infections such as HIV or multidrug-resistant organisms have been made more flexible, leading to a more inclusive transplantation policy. A key focus is on early transplant counselling, allowing patients the opportunity for transplantation before they develop acute exacerbations. These updated guidelines aim to maximise both the survival rates and the quality of life of transplant patients, through differentiated and risk-adjusted decision-making.

Pulmonary Hypertension and Lung Transplantation

Pulmonary artery hypertension (PAH), a subtype of pulmonary hypertension, is a rare end-stage lung disease. Bilateral lung and combined heart and lung transplantation have long been considered as a gold standard therapy for PAH.This manuscript reviewed the most up-to-date literature on lung transplantation for PAH, focusing particularly on risk stratification, donor allocation, bridging to transplantation (BTT), and intra- and postoperative management in both adult and pediatric patients.The last two decades have witnessed an important shift in the transplant indications and strategy for PAH. Newly introduced antihypertensive drugs have postponed the time of transplantation in eligible patients, thus reserving transplantation for severely ill high-risk patients on triple antihypertensive therapy. Furthermore, the widespread peritransplant use of veno-arterial extracorporeal membrane oxygenation (ECMO) enables cardiac remodeling after bilateral lung transplantation.The change in transplant strategy from combined heart and lung transplantation to bilateral lung transplantation renders more organs available for transplantation in an era of organ shortage. ECMO-bridging is a life-saving tool in selected PAH patients although associated with higher complications. Better organ allocation in PAH patients at high risk of decompensation may reduce the need for ECMO-bridging and may further improve outcomes.

Approach to Lung Transplantation in Pulmonary Arterial Hypertension: A Delphi Consensus on Behalf of the Transplant Task Force of the Pulmonary Vascular Research Institute

Lung transplantation is indicated for selected patients with advanced pulmonary arterial hypertension (PAH). We used a modified Delphi process to develop recommendations on care of patients with PAH undergoing lung transplantation. This Delphi panel was recruited from the Pulmonary Vascular Research Institute's Innovative Drug Discovery Initiative - Lung Transplantation Workstream, consisting of clinical and research experts in PAH and lung transplantation. In this process, 29 panelists were given open-ended questions, querying topics related to lung transplantation in PAH. A steering group converted the responses into discrete statements. Panelists then rated agreement using a Likert scale in two further survey rounds: -5 (strongly disagree) to 5 (strongly agree). Consensus was defined as mean ≥ 2.5 or ≤ -2.5, with a standard deviation not crossing zero. Consensus was reached on 141 of 223 statements. Notable areas of consensus were for early discussions about transplantation, and agreement with previously published referral and listing criteria. There was agreement that lung transplantation could be offered in sick candidates, including those with concurrent renal or hepatic insufficiency. Bilateral lung transplantation was considered the procedure of choice for most patients, with rare indications for heart-lung transplantation. Consensus on bridging strategies included use of veno-arterial extracorporeal membrane oxygenation and preemptive awake cannulation in those with severe right ventricular dysfunction. Consensus was also achieved on intraoperative use of invasive hemodynamic monitoring, and prolonged postoperative circulatory support guided by hemodynamic response and echocardiography. Patients with PAH undergoing transplantation require specialized management, which differs somewhat from other candidates.

Treatment algorithm for pulmonary arterial hypertension

Pulmonary arterial hypertension leads to significant impairment in haemodynamics, right heart function, exercise capacity, quality of life and survival. Current therapies have mechanisms of action involving signalling via one of four pathways: endothelin-1, nitric oxide, prostacyclin and bone morphogenetic protein/activin signalling. Efficacy has generally been greater with therapeutic combinations and with parenteral therapy compared with monotherapy or nonparenteral therapies, and maximal medical therapy is now four-drug therapy. Lung transplantation remains an option for selected patients with an inadequate response to therapies.

The Secondary Pulmonary Hypertension Diagnosis is Not Useful in Lung Allocation

BACKGROUND

In lung transplant, the United Network for Organ Sharing (UNOS) contains a diagnosis of secondary pulmonary hypertension (SPH). SPH and pulmonary arterial hypertension are treated the same in the allocation scoring system. It is not clear whether utilizing the SPH diagnosis instead of the primary diagnosis is helpful to patients or providers.

METHODS

Analysis of UNOS data from May 2005 through July 2021, comparing patients listed under the SPH diagnosis with patients listed under COPD and interstitial lung disease (ILD) who met criteria for PH (COPD-PH and ILD-PH, respectively), as well as patients listed under pulmonary arterial hypertension (primary pulmonary hypertension, PPH). Competing-risk analysis examined waitlist and post-transplant outcomes. An exploratory analysis of UNOS spirometry data was performed.

RESULTS

Compared to patients listed under the SPH diagnosis, patients with ILD-PH were more likely to undergo transplantation (adjusted HR: 1.34, 95% confidence interval: 1.16-1.54, P < .001), with no significant difference comparing the SPH diagnosis to PPH or to COPD-PH. Waitlist mortality did not vary between groups. Post-transplant survival was lower in patients with PPH (adjusted HR: 1.35, 95% confidence interval: 1.04-1.75, P = .025), with no significant difference comparing the SPH diagnosis to COPD-PH or ILD-PH. Spirometry failed to demonstrate a clear phenotype within the SPH diagnosis.

CONCLUSION

In an adjusted analysis, patients with advanced lung disease and secondary PH were more likely to undergo transplantation when listed for ILD than when listed under the SPH diagnosis. The SPH diagnosis is too clinically heterogeneous to be useful in predictive models and should be considered for removal from UNOS.

Transplantation, bridging, and support technologies in pulmonary hypertension

Despite the progress made in medical therapies for treating pulmonary hypertension (PH), a subset of patients remain susceptible to developing a maladaptive right ventricular phenotype. The effective management of end-stage PH presents substantial challenges, necessitating a multidisciplinary approach and early identification of patients prone to acute decompensation. Identifying potential transplant candidates and assessing the feasibility of such a procedure are pivotal tasks that should be undertaken early in the treatment algorithm. Inclusion on the transplant list is contingent upon a comprehensive risk assessment, also considering the specific type of PH and various factors affecting waiting times, all of which should inform the decision-making process. While bilateral lung transplantation is the preferred option, it demands expert intra- and post-operative management to mitigate the heightened risks of pulmonary oedema and primary graft dysfunction in PH patients. Despite the availability of risk assessment tools, the occurrence of acute PH decompensation episodes can be unpredictable, potentially leading to refractory right ventricular failure even with optimal medical intervention, necessitating the use of rescue therapies. Advancements in right ventricular assist techniques and adjustments to graft allocation protocols for the most critically ill patients have significantly enhanced the survival in intensive care, affording the opportunity to endure while awaiting an urgent transplant. Given the breadth of therapeutic options available, specialised centres capable of delivering comprehensive care have become indispensable for optimising patient outcomes. These centres are instrumental in providing holistic support and management tailored to the complex needs of PH patients, ultimately enhancing their chances of a successful transplant and improved long-term prognosis.

Pulmonary vascular resistance predicts the mortality in patients with bronchiectasis-associated pulmonary hypertension

OBJECTIVE

Pulmonary hypertension is a severe complication of bronchiectasis, characterized by elevated pulmonary vascular resistance (PVR) and subsequent right heart failure. The association between PVR and mortality in bronchiectasis-associated pulmonary hypertension has not been investigated previously.

METHODS

In the present study, a retrospective analysis was conducted on 139 consecutive patients diagnosed with bronchiectasis-associated pulmonary hypertension based on right heart catheterization, enrolled between January 2010 and June 2023. Baseline clinical characteristics and hemodynamic assessment were analyzed. The survival time for each patient was calculated in months from the date of diagnosis until the date of death or, if the patient was still alive, until their last visit.

RESULTS

Patients with bronchiectasis-associated pulmonary hypertension exhibited estimated survival rates of 89.5, 70, and 52.9 at 1-year, 3-year, and 5-year intervals respectively, with a median survival time of 67 months. Multivariable Cox regression analysis revealed that increased age [(adjusted hazard ratio per year 1.042, 95% confidence interval (CI) 1.008-1.076, P  = 0.015] and elevated PVR (adjusted HR per 1 Wood Units 1.115, 95% CI 1.015-1.224, P  = 0.023) were associated with an increased risk of all-cause mortality. In contrast, higher BMI was associated with a decreased risk of all-cause death (adjusted hazard ratio per 1 kg/m 2 0.915, 95% CI 0.856-0.979, P  = 0.009). Receiver-operating characteristic analyses identified a cutoff value for PVR at 4 Wood Units as predictive for all-cause death within 3 years [area under the curve (AUC) = 0.624; specificity= 87.5%; sensitivity= 35.8%; P  < 0.05]. Patients with a PVR greater than 4 Wood Units had a significantly higher risk of all-cause death compared with those with 4 Wood Units or less (adjusted hazard ratio 2.392; 95% CI 1.316-4.349; P  = 0.019). Notably, there were no significant differences in age, sex, BMI, WHO functional class, 6-min walk distance, and NT-proBNP levels at baseline between patients categorized as having 4 Wood Units or less or greater than 4 Wood Units for PVR.

CONCLUSION

Based on these data, PVR could serve as a discriminative marker for distinguishing between nonsevere pulmonary hypertension (PVR ≤ 4 Wood Units) and severe pulmonary hypertension (PVR > 4 Wood Units). The utilization of a PVR cutoff value of 4.0 Wood Units provides enhanced prognostic capabilities for predicting mortality.

Pushing the Survival Bar Higher: Two Decades of Innovation in Lung Transplantation

Survival after lung transplantation has significantly improved during the last two decades. The refinement of the already existing extracorporeal life support (ECLS) systems, such as extracorporeal membrane oxygenation (ECMO), and the introduction of new techniques for donor lung optimization, such as ex vivo lung perfusion (EVLP), have allowed the extension of transplant indication to patients with end-stage lung failure after acute respiratory distress syndrome (ARDS) and the expansion of the donor organ pool, due to the better evaluation and optimization of extended-criteria donor (ECD) lungs and of donors after circulatory death (DCD). The close monitoring of anti-HLA donor-specific antibodies (DSAs) has allowed the early recognition of pulmonary antibody-mediated rejection (AMR), which requires a completely different treatment and has a worse prognosis than acute cellular rejection (ACR). As such, the standardization of patient selection and post-transplant management has significantly contributed to this positive trend, especially at high-volume centers. This review focuses on lung transplantation after ARDS, on the role of EVLP in lung donor expansion, on ECMO as a principal cardiopulmonary support system in lung transplantation, and on the diagnosis and therapy of pulmonary AMR.

Iatrogenic esophageal dysmotility as a barrier to transplantation in pulmonary arterial hypertension

Esophageal dysmotility is identified as a contraindication to lung transplantation at some centers due to increased risks of acute rejection, pulmonary infection, and chronic lung allograft dysfunction. Phosphodiesterase-type 5 inhibitors (PDE5i) are a cornerstone pharmacotherapy for pulmonary arterial hypertension (PAH) and are known to exert off-target effects that may impact lung transplant candidacy, including impaired esophageal contractility and decreased lower esophageal sphincter tone. We report 2 patients with PAH who were initially declined listing for lung transplantation due to iatrogenic esophageal dysmotility induced by PDE5is. Upon discontinuation of PDE5i therapy, these patients experienced significant improvement in esophageal motility within 14 days and met the criteria for transplant listing at their centers. Recognizing and mitigating the off-target effects of PDE5i medications is critical for maximizing access to transplant for patients with PAH.

Impact of Extracorporeal Membrane Oxygenation Bridging Duration on Lung Transplant Outcomes

BACKGROUND

We sought to characterize the association between venovenous extracorporeal membrane oxygenation (VV-ECMO) bridging duration and outcomes in patients listed for lung transplantation.

METHODS

A retrospective observational study was conducted using the Organ Procurement and Transplantation Network (OPTN) database to identify adults (aged ≥18 years) who were listed for lung transplantation between 2016 and 2020 and were bridged with VV-ECMO. Patients were then stratified into groups, determined by risk inflection points, depending on the amount of time spent on pretransplant ECMO: group 1 (≤5 days), group 2 (6-10 days), group 3 (11-20 days), and group 4 (>20 days). Waiting list survival between groups was analyzed using Fine-Gray competing risk models. Posttransplant survival was compared using Cox regression.

RESULTS

Of 566 eligible VV-ECMO bridge-to-lung-transplant patients (median age, 54 years, 49% men), 174 (31%), 124 (22%), 130 (23%), and 138 (24%) were categorized as groups 1, 2, 3, and 4, respectively. Overall, median duration of VV-ECMO was 10 days (interquartile range, 1-211 days), and 178 patients (31%) died on the waiting list. In the Fine-Gray model, compared with group 1, patients bridged with longer ECMO durations in group 2 (subdistribution hazard ratio [SHR], 2.95; 95% CI, 1.63-5.35), group 3 (SHR, 3.96; 95% CI, 2.36-6.63), and group 4 (SHR, 4.33; 95% CI, 2.59-7.22, all P < .001) were more likely to die on the waiting list. Of 388 patients receiving a transplant, pretransplant ECMO duration was not associated with 1-year survival in Cox regression.

CONCLUSIONS

Prolonged duration of ECMO bridging was associated with worse waiting list mortality but did not impact survival after lung transplant. Prioritization of very early transplantation may improve waiting list outcomes in this population.

Cell-Free DNA Maps Tissue Injury and Correlates with Disease Severity in Lung Transplant Candidates

Rationale: Plasma cell-free DNA levels correlate with disease severity in many conditions. Pretransplant cell-free DNA may risk stratify lung transplant candidates for post-transplant complications. Objectives: To evaluate if pretransplant cell-free DNA levels and tissue sources identify patients at high risk of primary graft dysfunction and other pre- and post-transplant outcomes. Methods: This multicenter, prospective cohort study recruited 186 lung transplant candidates. Pretransplant plasma samples were collected to measure cell-free DNA. Bisulfite sequencing was performed to identify the tissue sources of cell-free DNA. Multivariable regression models determined the association between cell-free DNA levels and the primary outcome of primary graft dysfunction and other transplant outcomes, including Lung Allocation Score, chronic lung allograft dysfunction, and death. Measurements and Main Results: Transplant candidates had twofold greater cell-free DNA levels than healthy control patients (median [interquartile range], 23.7 ng/ml [15.1-35.6] vs. 12.9 ng/ml [9.9-18.4]; P < 0.0001), primarily originating from inflammatory innate immune cells. Cell-free DNA levels and tissue sources differed by native lung disease category and correlated with the Lung Allocation Score (P < 0.001). High pretransplant cell-free DNA increased the risk of primary graft dysfunction (odds ratio, 1.60; 95% confidence interval [CI], 1.09-2.46; P = 0.0220), and death (hazard ratio, 1.43; 95% CI, 1.07-1.92; P = 0.0171) but not chronic lung allograft dysfunction (hazard ratio, 1.37; 95% CI, 0.97-1.94; P = 0.0767). Conclusions: Lung transplant candidates demonstrate a heightened degree of tissue injury with elevated cell-free DNA, primarily originating from innate immune cells. Pretransplant plasma cell-free DNA levels predict post-transplant complications.

Outcomes of listing for lung and heart-lung transplantation in pulmonary hypertension: comparative experience in France and the UK

Background

Lung or heart-lung transplantation (LT/HLT) for severe pulmonary hypertension (PH) as the primary disease indication carries a high risk of waiting list mortality and post-transplant complications. France and the UK both have coordinated PH patient services but with different referral pathways for accessing LT services.

Methods

We conducted a comparative analysis of adult PH patients listed for LT/HLT in the UK and France.

Results

We included 211 PH patients in France (2006-2018) and 170 in the UK (2010-2019). Cumulative incidence of transplant, delisting and waiting list death within 3 years were 81%, 4% and 11% in France versus 58%, 10% and 15% in the UK (p<0.001 for transplant and delisting; p=0.1 for death). Median non-priority waiting time was 45 days in France versus 165 days in the UK (p<0.001). High-priority listing occurred in 54% and 51% of transplanted patients respectively in France and the UK (p=0.8). Factors associated with achieving transplantation related to recipients' height, male sex, clinical severity and priority listing status. 1-year post-transplant survival was 78% in France and 72% in the UK (p= 0.04).

Conclusion

Access to transplantation for PH patients is better in France than in the UK where more patients were delisted due to clinical deterioration because of longer waiting time. High rates of priority listing occurred in both countries. Survival for those achieving transplantation was slightly better in France. Ensuring optimal outcomes after transplant listing for PH patients is challenging and may involve early listing of higher risk patients, increasing donor lung utilisation and improving allocation rules for these specific patients.

Management of Pulmonary Arterial Hypertension

Pulmonary arterial hypertension (PAH) is a rare pulmonary vascular disease characterized by progressive pulmonary arterial remodeling, increased pulmonary vascular resistance, right ventricular dysfunction, and reduced survival. Effective therapies have been developed that target three pathobiologic pathways in PAH: nitric oxide, endothelin-1, and prostacyclin. Approved therapies for PAH include phosphodiesterase type-5 inhibitors, soluble guanylate cyclase stimulators, endothelin receptor antagonists, prostacyclin analogs, and prostacyclin receptor agonists. Management of PAH in the modern era incorporates multidimensional risk assessment to guide the use of these medications. For patients with PAH and without significant comorbidities, current guidelines recommend two oral medications (phosphodiesterase type-5 inhibitor and endothelin receptor antagonist) for low- and intermediate-risk patients, with triple therapy including a parenteral prostacyclin to be considered in those at high or intermediate-high risk. Combination therapy may be poorly tolerated and less effective in patients with PAH and cardiopulmonary comorbidities. Thus, a single-agent approach with individualized decisions to add-on other PAH therapies is recommended in older patients and those with significant comorbid conditions. Management of PAH is best performed in multidisciplinary teams located in experienced centers. Other core pillars of PAH management include supportive and adjunctive treatments including oxygen, diuretics, rehabilitation, and anticoagulation in certain patients. Patients with PAH who progress despite optimal treatment or who are refractory to best medical care should be referred for lung transplantation, if eligible. Despite considerable progress, PAH is often fatal and new therapies that reverse the disease and improve outcomes are desperately needed.

Lung Transplantation for Pulmonary Arterial Hypertension

TOPIC IMPORTANCE

Even though patients with pulmonary arterial hypertension have multiple therapeutic options, the disease can be refractory despite appropriate management. In patients with end-stage pulmonary arterial hypertension, lung transplantation has the potential both to extend survival and improve health-related quality of life. Pulmonary arterial hypertension is the only major diagnostic indication for transplantation that is not a parenchymal pulmonary process, and thus the care of these patients is unique.

REVIEW FINDINGS

This review focuses on the complexities of lung transplantation for patients with pulmonary arterial hypertension, presents the updated referral and listing criteria, and discusses the inequities in the organ allocation process that impact this disease group and the strategies to optimize outcomes for patients with pulmonary arterial hypertension who require lung transplantation.

SUMMARY

Lung transplantation is an effective and lifesaving therapy for patients with end-stage lung disease. Sadly, patients with pulmonary arterial hypertension face many challenges as it relates to transplantation including higher perioperative risks, inequities in the allocation system, and less favorable long-term outcomes. This review covers the complexities of transplantation in patients with pulmonary vascular disease.

Pulmonary Hypertension Association's 2022 International Conference Scientific Sessions Overview

The considerable progress made in recent years in the diagnosis, risk stratification, and treatment of pulmonary hypertension was highlighted during the most recent edition of the Pulmonary Hypertension Association Scientific Sessions, which was held in Atlanta, Georgia from June 9 to 11, 2022, with the theme: Vision for the PHuture: The Evolving Science and Management of PH. Content presented over the 3-day conference focused on scientific and management updates since the last sessions were held in 2018 and included didactic talks, debates, and roundtable discussions across a broad spectrum of topics related to pulmonary hypertension. This article aims to summarize the key messages from each of the session talks.