Survival benefits of heart and lung transplantation

Machine learning in lung transplantation: Where are we?

Lung transplantation has been accepted as a viable treatment for end-stage respiratory failure. While regression models continue to be a standard approach for attempting to predict patients' outcomes after lung transplantation, more sophisticated supervised machine learning (ML) techniques are being developed and show encouraging results. Transplant clinicians could utilize ML as a decision-support tool in a variety of situations (e.g. waiting list mortality, donor selection, immunosuppression, rejection prediction). Although for some topics ML is at an advanced stage of research (i.e. imaging and pathology) there are certain topics in lung transplantation that needs to be aware of the benefits it could provide.

Post-transplant Malignancies Show Reduced T-cell Abundance and Tertiary Lymphoid Structures as Correlates of Impaired Cancer Immunosurveillance

PURPOSE

An increased risk to develop cancer is one of the most challenging negative side effects of long-term immunosuppression in organ transplant recipients and impaired cancer immunosurveillance is assumed as underlying mechanism. This study aims to elucidate transplant-related changes in the tumor immune microenvironment (TME) of cancer.

EXPERIMENTAL DESIGN

Data from 123 organ transplant recipients (kidney, heart, lung, and liver) were compared with historic data from non-immunosuppressed patients. Digital image analysis of whole-section slides was used to assess abundance and spatial distribution of T cells and tertiary lymphoid structures (TLS) in the TME of 117 tumor samples. Expression of programmed cell death 1 ligand 1 (PD-L1) and human-leucocyte-antigen class I (HLA-I) was assessed on tissue microarrays.

RESULTS

We found a remarkably reduced immune infiltrate in the center tumor (CT) regions as well as the invasive margins (IM) of post-transplant cancers. These differences were more pronounced in the IM than in the CT and larger for CD8+ T cells than for CD3+ T cells. The Immune-score integrating results from CT and IM was also lower in transplant recipients. Density of TLS was lower in cancer samples of transplant recipients. The fraction of samples with PD-L1 expression was higher in controls whereas decreased expression of HLA-I was more common in transplant recipients.

CONCLUSIONS

Our study demonstrates the impact of immunosuppression on the TME and supports impaired cancer immunosurveillance as important cause of post-transplant cancer. Modern immunosuppressive protocols and cancer therapies should consider the distinct immune microenvironment of post-transplant malignancies.

Survival on the Heart Transplant Waiting List

Importance

With continuing improvements in medical devices and more than a decade since the 2006 United Network for Organ Sharing (UNOS) allocation policy, it is pertinent to assess survival among patients on the heart transplantation waiting list, especially given the recently approved 2018 UNOS allocation policy.

Objectives

To assess survival outcomes among patients on the heart transplant waiting list during the past 3 decades and to examine the association of ventricular assist devices (VADs) and the 2006 UNOS allocation policy with survival.

Design, Setting, and Participants

A retrospective cross-sectional used the UNOS database to perform an analysis of 95 323 candidates wait-listed for heart transplantation between January 1, 1987, and December 29, 2017. Candidates for all types of combined transplants were excluded (n = 2087). Patients were followed up from the time of listing to death, transplantation, or removal from the list due to clinical improvement. Competing-risk, Kaplan-Meier, and multivariable Cox proportional hazards regression analyses were used.

Main Outcomes and Measures

The analysis involved an unadjusted and adjusted survival analysis in which the primary outcome was death on the waiting list. Because of changing waiting list preferences and policies during the study period, the intrinsic risk of death for wait-listed candidates was assessed by individually analyzing, comparing, and adjusting for several candidate risk factors.

Results

In total, 95 323 candidates (72 915 men [76.5%]; mean [SD] age, 51.9 [12.0] years) were studied. In the setting of changes in listing preferences, 1-year survival on the waiting list increased from 34.1% in 1987-1990 to 67.8% in 2011-2017 (difference in proportions, 0.34%; 95% CI, 0.32%-0.36%; P < .001). The 1-year waiting list survival for candidates with VADs increased from 10.2% in 1996-2000 to 70.0% in 2011-2017 (difference in proportions, 0.60%; 95% CI, 0.58%-0.62%; P < .001). Similarly, in the setting of changing mechanical circulatory support indications, the 1-year waiting list survival for patients without VADs increased from 53.9% in 1996-2000 to 66.5% in 2011-2017 (difference in proportions, 0.13%; 95% CI, 0.12%-0.14%; P < .001). In the decade prior to the 2006 UNOS allocation policy, the 1-year waiting list survival was 51.1%, while in the decade after it was 63.9% (difference in proportions, 0.13%; 95% CI, 0.12%-0.14%; P < .001). In adjusted analysis, each time period after 1987-1990 had a marked decrease in waiting list mortality.

Conclusions and Relevance

This study found temporally associated increases in heart transplant waiting list survival for all patient groups (with or without VADs, UNOS status 1 and status 2 candidates, and candidates with poor functional status).

A 3-Decade Analysis of Pancreatic Adenocarcinoma After Solid Organ Transplant

OBJECTIVE

Solid organ transplant (SOT) recipients have moderately increased risk of pancreatic adenocarcinoma (PAC). We evaluated the incidence and survival of PAC in 2 cohorts and aimed to identify potential risk factors.

METHODS

This study performed a retrospective cohort analysis. Cohort A was extracted from the United Network of Organ Sharing data set and cohort B from SOT recipients evaluated at 3 Mayo Clinic transplant centers. The primary outcome was age-adjusted annual incidence of PAC. Descriptive statistics, hazard ratios, and survival rates were compared.

RESULTS

Cohort A and cohort B included 617,042 and 29,472 SOT recipients, respectively. In cohort A, the annual incidence rate was 12.78 per 100,000 in kidney-pancreas, 13.34 in liver, and 21.87 in heart-lung transplant recipients. Receiving heart-lung transplant, 50 years or older, and history of cancer (in either recipient or donor) were independent factors associated with PAC. Fifty-two patients developed PAC in cohort B. Despite earlier diagnosis (21.15% with stage I-II), survival rates were similar to those reported for sporadic (non-SOT) patients.

CONCLUSIONS

We report demographic and clinical risk factors for PAC after SOT, many of which were present before transplant and are common to sporadic pancreatic cancer. Despite the diagnosis at earlier stages, PAC in SOT portends a very poor survival.

25-year follow-up after lung transplantation at Lund University Hospital in Sweden: superior results obtained for patients with cystic fibrosis

OBJECTIVES

In Sweden, two centres perform lung transplantation for a population of about 9 million and the entire population is covered for lung transplantation by government health insurance. Lund University Hospital is one of these centres. This retrospective report reviews the 25-year experience of the Skåne University Hospital Lung Transplant Program with particular emphasis on short-term outcome and long-term survival but also between different subgroups of patients and types of transplant [single-lung transplantation (SLTx) versus double-lung transplantation (DLTx)] procedure performed.

METHODS

Between January 1990 and June 2014, 278 patients underwent lung transplantation at the Skåne University Hospital Sweden. DLTx was performed in 172 patients, SLTx was performed in 97 patients and heart-lung transplantation was performed in 9 patients. In addition, 15 patients required retransplantation (7 DLTx and 8 SLTx).

RESULTS

Overall 1-, 5-, 10-, 15- and 20-year survival rates were 88, 65, 49, 37 and 19% for the whole cohort. DLTx recipients showed 1-, 5-, 10- and 20-year survival rates of 90, 71, 60 and 30%, compared with SLTx recipients with 1-, 5-, 10- and 20-year survival rates of 83, 57, 34 and 6% (P < 0.05), respectively. Comparing the use of intraoperative extracorporeal membrane oxygenation, extracorporeal circulation (ECC) and no circulatory support in the aspect of survival, a significant difference in favour of intraoperative ECC was seen.

CONCLUSIONS

Superior long-term survival rates were seen in recipients diagnosed with cystic fibrosis, α1-antitrypsin deficiency and pulmonary hypertension. DLTx showed better results compared with SLTx especially at 10 years post-transplant. In the present study, we present cumulative incidence rates of bronchiolitis obliterans syndrome of 15% at 5 years, 26% at 10 years and 32% at 20 years post-transplant; these figures are in line with the lowest rates presented internationally.

Mechanoactive materials in cardiac science

Mechanically active biomaterials such as shape memory materials, liquid crystal elastomers, dielectric elastomer actuators, and conductive polymers could be used in mechanical devices to augment heart function or condition cardiac cells and artificial tissues for regenerative medicine solutions.

Impact of donor and recipient hepatitis C status in lung transplantation

BACKGROUND

Studies of lung transplantation in the setting of donors or recipients with hepatitis C virus (HCV) have been limited but have raised concerns about outcomes associated with this infection.

METHODS

Lung transplant cases in the United Network for Organ Sharing (UNOS) database from 1994 to 2011 were analyzed for the HCV status of both donor and recipient. First, among HCV-negative recipients, those who received a lung from an HCV-positive donor (HCV(+) D) were compared with those who received an HCV-negative lung (HCV(-) D). Donor, recipient and operative characteristics as well as outcomes were compared between groups, and overall survival was compared after adjustment for confounders. In a second analysis, HCV-positive recipients (HCV(+) R) were compared with HCV-negative recipients (HCV(-) R). The analysis was stratified by era (1994 to 1999 and 2000 to 2011) and long-term survival was compared.

RESULTS

Of 16,604 HCV-negative patients in the UNOS database, 28 (0.2%) received a lung from an HCV(+) D, with use of HCV(+) D decreasing significantly over time. Overall survival (OS) was shorter in the HCV(+) D group (median survival: 1.3 vs 5.1 years; p = 0.002). Results were confirmed in adjusted analyses. After inclusion criteria were met, 289 (1.7%) of the lung transplant recipients were HCV(+) R. These patients appeared similar to their HCV(-) R counterparts, except they were older and had more limited functional status. OS was significantly lower in HCV-positive individuals during the early era (median survival: 1.7 vs 4.5 years; p = 0.004), but not the recent era (median survival: 4.4 vs 5.4 years; p = 0.100). Again, results were confirmed by adjusted analysis.

CONCLUSIONS

HCV-positive status is a rare problem when considering both lung recipients and donors. Current data demonstrate significantly worse outcomes for HCV-negative patients receiving an HCV(+) lung; however, since 2000, HCV(+) recipients undergoing lung transplantation appear to have survival approximating that of HCV(-) recipients, an improvement from previous years. Recent medical advances in treatment for HCV may further improve outcomes in these groups.

Predicting the graft survival for heart-lung transplantation patients: an integrated data mining methodology

BACKGROUND

Predicting the survival of heart-lung transplant patients has the potential to play a critical role in understanding and improving the matching procedure between the recipient and graft. Although voluminous data related to the transplantation procedures is being collected and stored, only a small subset of the predictive factors has been used in modeling heart-lung transplantation outcomes. The previous studies have mainly focused on applying statistical techniques to a small set of factors selected by the domain-experts in order to reveal the simple linear relationships between the factors and survival. The collection of methods known as 'data mining' offers significant advantages over conventional statistical techniques in dealing with the latter's limitations such as normality assumption of observations, independence of observations from each other, and linearity of the relationship between the observations and the output measure(s). There are statistical methods that overcome these limitations. Yet, they are computationally more expensive and do not provide fast and flexible solutions as do data mining techniques in large datasets.

PURPOSE

The main objective of this study is to improve the prediction of outcomes following combined heart-lung transplantation by proposing an integrated data-mining methodology.

METHODS

A large and feature-rich dataset (16,604 cases with 283 variables) is used to (1) develop machine learning based predictive models and (2) extract the most important predictive factors. Then, using three different variable selection methods, namely, (i) machine learning methods driven variables-using decision trees, neural networks, logistic regression, (ii) the literature review-based expert-defined variables, and (iii) common sense-based interaction variables, a consolidated set of factors is generated and used to develop Cox regression models for heart-lung graft survival.

RESULTS

The predictive models' performance in terms of 10-fold cross-validation accuracy rates for two multi-imputed datasets ranged from 79% to 86% for neural networks, from 78% to 86% for logistic regression, and from 71% to 79% for decision trees. The results indicate that the proposed integrated data mining methodology using Cox hazard models better predicted the graft survival with different variables than the conventional approaches commonly used in the literature. This result is validated by the comparison of the corresponding Gains charts for our proposed methodology and the literature review based Cox results, and by the comparison of Akaike information criteria (AIC) values received from each.

CONCLUSIONS

Data mining-based methodology proposed in this study reveals that there are undiscovered relationships (i.e. interactions of the existing variables) among the survival-related variables, which helps better predict the survival of the heart-lung transplants. It also brings a different set of variables into the scene to be evaluated by the domain-experts and be considered prior to the organ transplantation.

Coping and quality of life in patients awaiting lung transplantation

OBJECTIVE

Patients with end-stage lung disease (ESLD) experience significant decrements in quality of life (QOL). Although coping strategies are related to QOL in patients with ESLD, the extent to which specific native lung disease moderates this relationship is unknown.

METHODS

We investigated the relationship between coping, native lung disease, and QOL among 187 patients awaiting lung transplantation, including 139 patients with chronic obstructive pulmonary disease (COPD) and 48 with cystic fibrosis (CF). Participants completed a psychosocial battery assessing psychological QOL, physical QOL, and coping strategies.

RESULTS

For both COPD and CF patients, higher levels of Active Coping (P< .0001) and lower levels of Disengagement (P< .0001) were associated with better psychological QOL. For physical QOL, we observed a Native Disease x Coping interaction (P=.01) such that Active Coping was associated with better physical QOL in patients with COPD but not in patients with CF.

CONCLUSIONS

The relationship between coping and QOL may vary as a function of native lung disease. Patients' native disease may need to be considered in order to develop effective interventions to help patients cope successfully with ESLD.

Telephone-based coping skills training for patients awaiting lung transplantation

Impaired quality of life is associated with increased mortality in patients with advanced lung disease. Using a randomized controlled trial with allocation concealment and blinded outcome assessment at 2 tertiary care teaching hospitals, the authors randomly assigned 328 patients with end-stage lung disease awaiting lung transplantation to 12 weeks of telephone-based coping skills training (CST) or to usual medical care (UMC). Patients completed a battery of quality of life instruments and were followed for up to 3.4 years to assess all-cause mortality. Compared with UMC, CST produced lower scores on perceived stress, anxiety, depressive symptoms, and negative affect and improved scores on mental health functioning, optimism, vitality, and perceived social support. There were 29 deaths (9%) over a mean follow-up period of 1.1 year. Survival analyses revealed that there was no difference in survival between the 2 groups. The authors conclude that a telephone-based CST intervention can be effectively delivered to patients awaiting lung transplantation. Despite the severity of pulmonary disease in this patient population, significant improvements in quality of life, but not somatic measures or survival to transplant, were achieved.

The Copenhagen National Lung Transplant Group: survival after single lung, double lung, and heart-lung transplantation

OBJECTIVE

To review the 13-year clinical experience of a single center's adult lung transplantation program.

METHODS

From January 1992 to December 2003, 369 lung transplantations were performed on 362 patients. Single lung transplantation was performed in 234 cases, double lung transplantation in 113 cases (comprising en-bloc double lung transplantation in 44 cases and bilateral sequential lung transplantation in 69 cases), heart-lung transplantation in 21 cases, and lobe of lung transplantation in 1 case. Recipient diagnoses included chronic obstructive pulmonary disease (COPD) (n = 175), alpha1 antitrypsin (alpha1AT) deficiency (n = 86), cystic fibrosis (n = 36), pulmonary fibrosis (n = 20), Eisenmenger syndrome and secondary pulmonary hypertension (n = 24), primary pulmonary hypertension (n = 8), sarcoidosis (n = 7), silicosis (n = 4), bronchiectasis (n = 1), and graft-vs-host disease (n = 1).

RESULTS

For patients surviving to discharge, the median duration of the intensive care unit stay was 3 days (1-67), and the median duration of the post-operative hospital stay was 37 days (16-144). Mortality for the entire series was 6% at 30 days and 10% at 90 days. The main causes of post-operative inpatient death were primary graft failure (41%), sepsis (29%), cardiac (15%), and hemorrhage (9%). The 1-, 3-, 5-, and 10-year actuarial survival rates for the entire series was 81%, 68%, 63%, and 36%, respectively. There were no significant differences in survival between types of transplant. No significant differences in survival were seen between alpha(1)AT deficiency and COPD patients after stratifying for age. Cox regression analysis demonstrated that age 60 years or older, donor age 50 years or older, and a recipient pre-operative body mass index of 25 or higher were independent predictors of poor survival.

CONCLUSIONS

This center has 1-, 3-, and 5-year survival rates comparable to other high volume centers. Recipient age, pre-operative body mass index, and donor age significantly influence outcome after lung transplantation.

Gas exchange and exercise capacity affect neurocognitive performance in patients with lung disease

OBJECTIVE

This study examined the relationship between cognitive functioning and the severity of underlying lung disease in patients awaiting lung transplantation.

METHODS

Ninety-four patients with end-stage lung disease completed a test battery to assess cognitive performance in two domains: executive functioning/attention (Trails A and B, COWA, Animal Naming, Stroop Color-Word Test, Digit Symbol, and the 2 & 7 Test) and verbal memory (Digit Span-Backward and Forward, WMS-R Logical Memory and Paired Verbal Associates).

RESULTS

Thirty-seven percent of the patients demonstrated moderate to severe cognitive impairment data on two or more tests. Adjusting for age and education, there were no statistically significant differences on executive functioning or verbal memory as a function of specific lung disease diagnosis. Lower PCO2 values were associated with better cognitive performance on latent measures of executive functioning and attention (p = .006) and verbal memory (p = .009), whereas higher PO2 values tended to be associated with better performance on the executive functioning/attention measure (p = .064). Distance walked in 6 minutes was positively related to verbal memory (p < .023).

CONCLUSIONS

Impaired neurocognitive functioning may be relatively common in patients awaiting lung transplantation and is associated with ineffective pulmonary gas exchange and reduced exercise tolerance.

Assessment of survival benefit after lung transplantation by patient diagnosis

BACKGROUND

Lung transplantation has become an established procedure for treating patients with endstage lung disease, resulting in broadening criteria for recipient selection. The survival benefit for some patient groups has yet to be established.

METHODS

We reviewed 653 patients accepted for lung transplantation at our center. Patients were categorized into 6 diagnosis groups: cystic fibrosis (174), obstructive lung disease (163), pulmonary fibrosis (100), Eisenmenger's syndrome (76), pulmonary hypertension (68), bronchiectasis (51), and other (21). Using Cox regression, we estimated the time at which early operative risk of death fell below pre-operative risk levels (crossover point) and the point at which early high post-operative risk was offset by later low risk (equity point). The relative benefits of single lung vs double lung/heart-lung transplantation were assessed for patients with obstructive lung disease and pulmonary fibrosis.

RESULTS

Post-operative risk of death fell below pre-operative risk levels for all diagnosis groups, indicating a survival advantage. The equity point was achieved for all distinct diagnosis groups (except Eisenmenger's); this survival benefit was significant for patients with obstructive lung disease, cystic fibrosis, and pulmonary hypertension. Single lung vs double lung/ heart-lung comparisons showed no significant difference in survival benefit.

CONCLUSION

All survival benefit patient groups achieve after lung transplantation, with the exception of patients with Eisenmenger's syndrome, who may have prolonged survival while listed. Differences in survival benefit between single lung and double or heart-lung transplantation are not significant for patients with obstructive lung disease or pulmonary fibrosis.

beta-blocker therapy: a standard of care for heart failure

beta-Adrenergic-blocking agents underwent extensive research over the past 2 decades and emerged as a proven state-of-art therapy for the failing human heart. Through blockade of chronically elevated cardiac adrenergic stimulation, selective and nonselective agents with vasodilating properties prevent progression of myocardial dysfunction and cardiac remodeling. Most important, beta-adrenergic blockers added to conventional therapy of vasodilators and diuretics significantly increase survival to a 5-year rate similar to that of cardiac transplantation. The agents also significantly reduce hospitalizations, improve quality of life, and are well tolerated in clinical trials. The challenge in treating heart failure is to ensure that every eligible patient receives these life-saving drugs.

Adenovirus-mediated genetic manipulation of the myocardial beta-adrenergic signaling system in transplanted hearts

OBJECTIVES

Ex vivo perfusion of the cardiac allograft during organ procurement is an ideal environment for adenoviral vectors with transgenes that target improving graft contractility. One such target is the beta-adrenergic receptor-signaling system, in which alterations in transgenic mice have elucidated novel means to improve the function of the heart in vivo. The purpose of the current study was to determine the functional consequences of beta-adrenergic receptor manipulation in a rabbit model of cardiac allograft transplantation.

METHODS

New Zealand White rabbits weighing 3 kg served as recipients to 1-kg outbred donors. Donor hearts were arrested and harvested, and 1 of 3 adenoviral constructs was administered into the aortic root perfusing the graft. Transgenes delivered encoded either the human beta(2)-adrenergic receptor, a peptide inhibitor of beta-adrenergic receptor densensitization, or the marker transgene beta-galactosidase.

RESULTS

Five days after cervical heterotopic transplantation, left ventricular performance was measured on a Langendorff apparatus. A moderate pattern of rejection was seen in all grafts. Biventricular myocyte expression of beta-galactosidase was observed, and beta(2)-adrenergic receptor density was elevated 10-fold in grafts that received adeno-beta(2)-adrenergic receptor. Left ventricular systolic and diastolic performance was significantly increased in grafts transfected with either adeno-beta(2)-adrenergic receptor or adeno-beta-adrenergic receptor densensitization compared with control grafts that received adeno-beta-galactosidase.

CONCLUSIONS

Ex vivo adenovirus-mediated gene transfer is feasible in a rabbit allograft model and, more important, genetic manipulation of beta-adrenergic receptor signaling either by increasing beta(2)-adrenergic receptor density or blocking endogenous receptor desensitization improves graft function acutely in this allograft model.

Routine surveillance endomyocardial biopsy: late rejection after heart transplantation

BACKGROUND

Transplant programs use routine surveillance endomyocardial biopsies (RSEMB), which are performed at preset intervals to diagnose cardiac rejection. This retrospective study determined the incidence of graft rejection detected by RSEMB.

METHODS

The records of 95 patients who underwent heart transplantation between 1987 and 1995 were reviewed. Rejection incidence was recorded for 80 patients who survived at least 30 days, with a mean follow-up of 35 months.

RESULTS

One thousand five hundred sixteen total biopsies were performed; 1,170 were RSEMB. Four hundred seventy-five total rejection episodes occurred and 269 (56%) were diagnosed by RSEMB. Two distinct patient groups were identified. The majority (70 patients), had a decline in the incidence of rejection and no rejection episodes were identified by RSEMB after 36 months. In contrast, the high rejection group (10 patients) had a significantly higher ongoing rejection rate (p < or = 0.04 to p < or = 0.001) throughout their postoperative course up to 72 months.

CONCLUSIONS

The majority of our transplant patients demonstrate a decrease in rejection with time and do not require RSEMB beyond 30 months. We identified a group of patients who exhibited a higher rate of rejection and need continued RSEMB.