Waiting list and post-transplant outcome in Sweden after national centralization of heart transplant surgery.

BACKGROUND: Previous studies have demonstrated an association between transplantation rate per center and postoperative mortality after heart transplantation. In 2011, Sweden centralized heart transplants and waiting lists, reducing the number of centers from 3 to 2. We aimed to assess the active waiting time and pre- and post-transplant mortality before and after centralization. METHODS: Heart transplantations performed in Sweden between January 1, 2001 and December 31, 2020 were included. Background and donor organ supply data were collected from Scandiatransplant, the Swedish Thoracic Transplant Registry, and the Swedish Cardiac Surgery Registry. The Fine and Gray methods were applied to visualize cumulative incidence curves and conduct competing risk regressions. A Cox model was used to adjust for factors influencing time to post-transplant death. RESULTS: When comparing the two eras, the median active waiting time increased from 54 to 71 days (p = 0.015). The risk of mortality on the waiting list decreased in the later era (subhazard ratio 0.43; [95% confidence interval {CI} 0.25-0.74]; p = 0.002). The number of heart transplantation procedures (including pediatric patients) increased by 53%. There was a significant difference in organ utilization between eras (p = 0.033; chi-square test). 30-day and 1-year survival post-transplant rates for adults increased from 90.8% to 97.8% (p < 0.001) and from 87.9% to 94.6% (p < 0.001), respectively. 1-year mortality was reduced by 63% (hazard ratio 0.37; 95% CI 0.22-0.61). CONCLUSIONS: This nationwide study examined patients listed for and undergoing heart transplantation before and after the centralization of waiting lists and surgeries in Sweden. Waiting list mortality decreased, and 1-year post-transplantation survival was improved.

Diastolic Filling in Patients After Heart Transplantation Is Impaired Due to an Altered Geometrical Relationship Between the Left Atrium and Ventricle.

BACKGROUND: The geometrical relationship between atrial and ventricular short-axis cross-sectional area determines the hydraulic forces acting on intracardiac blood. This is important for diastolic filling. In patients undergoing heart transplantation (HTx), the left atrium is often enlarged as a result of the standard surgical technique. We hypothesized that diastolic filling in HTx patients is affected by the surgery altering the geometrical relationship between atrium and ventricle. METHODS AND RESULTS: This retrospective, cross-sectional study included 25 HTx patients (median age, 52 [range, 25-70] years), 15 patients with heart failure with reduced ejection fraction (median age, 63 [range, 52-75] years), 15 patients with heart failure with preserved ejection fraction (median age, 74 [range, 56-82] years), and 15 healthy controls (median age, 64 [range, 58-67] years) who underwent cardiac magnetic resonance imaging. Left ventricular, atrial, and total heart volumes (THV) were obtained. Atrioventricular area difference at end diastole and end systole was calculated as the largest ventricular short-axis area minus the largest atrial short-axis area. Left atrial minimum volume normalized for THV (LAmin/THV) was larger in HTx patients (median, 0.13 [range, 0.07-0.19]) compared with controls (median, 0.05 [range, 0.03-0.08], P <0.001), whereas left ventricular volume normalized for THV (left ventricular end-diastolic volume/THV) was similar between HTx and controls (median, 0.19 [range, 0.12-0.24] and median, 0.22 [range, 0.20-0.25], respectively). At end diastole, when atrioventricular area difference reached its largest positive value in controls, 11 HTx patients (44%) had a negative atrioventricular area difference, indicating impaired diastolic filling. CONCLUSIONS: Diastolic filling is impaired in HTx patients due to an altered geometrical relationship between the left atrium and ventricle. When performing cardiac transplantation, a surgical technique that creates a smaller left atrium may improve diastolic filling by aiding hydraulic forces.

Pleiotropic effects of melanin pigmentation: haemoparasite infection intensity but not telomere length is associated with plumage morph in black sparrowhawks.

There is increasing recognition of the potential pleiotropic effects of melanin pigmentation, particularly on immunity, with reports of variation in haemoparasite infection intensity and immune responses between the morphs of colour-polymorphic bird species. In a population of the black sparrowhawk (Accipiter melanoleucus) in western South Africa, light morphs have a higher haemoparasite infection intensity, but no physiological effects of this are apparent. Here, we investigate the possible effects of haemoparasite infection on telomere length in this species and explore whether relative telomere length is associated with either plumage morph or sex. Using quantitative polymerase chain reaction analysis, we confirmed that dark morphs had a lower haemoparasite infection intensity than light morphs. However, we found no differences in telomere length associated with either the haemoparasite infection status or morph in adults, although males have longer telomeres than females. While differences in haemoparasite intensity between morphs are consistent with pleiotropic effects of melanin pigmentation in the black sparrowhawk, we found no evidence that telomere length was associated with haemoparasite infection. Further work is needed to investigate the implications of possible pleiotropic effects of plumage morph and their potential role in the maintenance of colour polymorphism in this species.

Impact of prolonged storage time on homograft ultrastructures: an attempt to find optimal guidelines for homograft processing.

According to guidelines, total ischemic time for homografts at processing must be kept short to avoid degeneration. Many homografts are discarded due to practical inability to finish all steps from procurement to cryopreservation within the time limit. Although, several studies have shown that homografts with prolonged ischemic time show adequate quality and performance. Twenty aortic and 12 pulmonary homografts were collected and biopsies were retrieved at preparation (day 0) and after 1, 2, 3, 4, 7, 14, 21, 28, and 60 days in antibiotic decontamination at 4 °C. Biopsies were prepared for light microscopy (LM) and transmission electron microscopy (TEM). Assessment generated scores for cells, elastin, and collagen. Relative differences between times were compared with Wilcoxon signed rank test. Bonferroni corrected p value of 0.0056 was considered significant. LM could only reveal decrease in cell count at 60 days in aortic homografts, no other differences was detected. TEM showed affected cell appearance in day 3 and day 4 and beyond for aortic and pulmonary homografts respectively. Elastin appearance was affected at day 60 for aortic and day 21 for pulmonary homografts. Collagen appearance was affected at day 28 for aortic homografts, with no significant differences in pulmonary homografts. Cell degeneration starts early after homograft procurement, but elastic and collagen fibers are more resistant to degeneration. Overall structure integrity as seen in LM was not affected at all, while TEM could reveal small degeneration signs in individual elastic fibers and collagen bundles at 21 and 28 days respectively.

Cover crop cultivation strategies in a Scandinavian context for climate change mitigation and biogas production - Insights from a life cycle perspective.

Cover crop cultivation can be a vital strategy for mitigating climate change in agriculture, by increasing soil carbon stocks and resource efficiency within the cropping system. Another mitigation option is to harvest the cover crop and use the biomass to replace greenhouse gas-intensive products, such as fossil fuels. Harvesting cover crop biomass could also reduce the risk of elevated N2O emissions associated with cover crop cultivation under certain conditions, which would offset much of the mitigation potential. However, harvesting cover crops also reduces soil carbon sequestration potential, as biomass is removed from the field, and cultivation of cover crops requires additional field operations that generate greenhouse gas emissions. To explore these synergies and trade-offs, this study investigated the life cycle climate effect of cultivating an oilseed radish cover crop under different management strategies in southern Scandinavia. Three alternative scenarios (Incorporation of biomass into soil; Mowing and harvesting aboveground biomass; Uprooting and harvesting above- and belowground biomass) were compared with a reference scenario with no cover crop. Harvested biomass in the Mowing and Uprooting scenarios was assumed to be transported to a biogas plant for conversion to upgraded biogas, with the digestate returned to the field as an organic fertiliser for the subsequent crop. The climate change mitigation potential of cover crop cultivation was found to be 0.056, 0.58 and 0.93 Mg CO2-eq ha-1 in the Incorporation, Mowing and Uprooting scenario, respectively. The Incorporation scenario resulted in the highest soil carbon sequestration, but also the greatest soil N2O emissions. Substitution of fossil diesel showed considerable mitigation potential, especially in the Uprooting scenario, where biogas production was highest. Sensitivity analysis revealed a strong impact of time of cover crop establishment, with earlier establishment leading to greater biomass production and thus greater mitigation potential.

Impact of storage time prior to cryopreservation on mechanical properties of aortic homografts.

Optimal time spans in homograft procurement are still debatable among tissue banks and needs to be further investigated. Cell viability decreases at longer preparation intervals, but the effect on collagen and elastic fibers has not been investigated to the same extent. These fibers are of importance to the homograft elasticity and strength. The objective of this study was to analyze the mechanical properties of homograft tissue at different time spans in the procurement process. Ten aortic homografts were collected at the Tissue Bank in Lund. Twelve samples were obtained from each homograft, cryopreserved in groups of three after 2-4 days, 7-9 days, 28-30 days, and 60-62 days in antibiotic decontamination. Mechanical testing was performed with uniaxial tensile tests, calculating elastic modulus, yield stress and energy at yield stress. Two randomly selected samples were assessed with light microscopy. Procurement generated a total of 120 samples, with 30 samples in each time group. Elastic modulus and yield stress was significantly higher in samples cryopreserved after 2-4 days (2.7 MPa (2.5-5.0) and 0.78 MPa (0.68-1.0)) compared to 7-9 days (2.2 MPa (2.0-2.6) and 0.53 MPa (0.46-0.69)), p = 0.008 and 0.011 respectively. Light microscopy did not show any difference in collagen and elastin at different time spans. There was a significant decrease in elastic modulus and yield stress after 7 days of decontamination at 4 °C compared to 2-4 days. This could indicate some deterioration of elastin and collagen at longer decontamination intervals. Clinical significance of these findings remains to be clarified.

Cholecystectomy and ERCP in pregnancy: a nationwide register-based study.

OBJECTIVE: The objective was to examine the outcomes of cholecystectomy and endoscopic retrograde cholangiopancreatography (ERCP) during pregnancy and compare these outcomes with those in nonpregnant women of fertile age. SUMMARY BACKGROUND DATA: Although both laparoscopic cholecystectomy and ERCP are considered safe and feasible in pregnant patients, there is still concern and uncertainty regarding gallstone intervention during pregnancy. This study aimed to investigate outcomes in pregnant patients compared to outcomes in nonpregnant patients. METHODS: Data on all female patients aged 18-45 years were retrieved from the Swedish Registry for Gallstone Surgery and Endoscopic Retrograde Cholangiopancreatography. The patients were divided into groups according to intervention: cholecystectomy, ERCP, or a combination thereof. Differences between pregnant and nonpregnant patients were analyzed. RESULTS: A total of 21 328 patients were included, with 291 cholecystectomy and 63 ERCP procedures performed in pregnant patients. At the 30-day follow-up, more complications after cholecystectomy were registered for pregnant patients. However, pregnancy was not a significant risk factor for adverse events when adjusting for previous complicated gallstone disease, intraoperative complications, emergency surgery, and common bile duct stones. There were no differences in outcomes when comparing cholecystectomy among the different trimesters. ERCP had no significant effect on outcomes at the 30-day follow-up. CONCLUSION: Cholecystectomy, ERCP, and combinations thereof are safe during pregnancy.

Inequality persists in a large citizen science programme despite increased participation through ICT innovations.

Biological recording is a prominent and widely practised form of citizen science, but few studies explore long-term demographic trends in participation and knowledge production. We studied long-term demographic trends of age and gender of participants reporting to a large online citizen science multi-taxon biodiversity platform ( www.artportalen.se ). Adoption by user communities and continually developing Information and Communications Technologies (ICTs) greatly increased the number of participants reporting data, but profound long-term imbalances in gender contribution across species groups persisted over time. Reporters identifying as male dominated in numbers, spent more days in the field reporting and reported more species on each field day. Moreover, an age imbalance towards older participants amplified over time. As the first long-term study of citizen participation by age and gender, our results show that it is important for citizen science project developers to account for cultural and social developments that might exclude participants, and to engage with underrepresented and younger participants. This could facilitate the breadth of engagement and learning across a larger societal landscape, ensure project longevity and biodiversity data representation (e.g. mitigate gender bias influence on the number of reports of different species groups).

Automatic Annotation of PubMed Articles with MeSH Qualifiers.

The Medical Subject Headings (MeSH) is a comprehensive indexing vocabulary used to label millions of books and articles on PubMed. The MeSH annotation of a document consists of one or more descriptors, the main headings, and of qualifiers, subheadings specific to a descriptor. Currently, there are more than 34 million documents on PubMed, which are manually tagged with MeSH terms. In this paper, we describe a machine-learning procedure that, given a document and its MeSH descriptors, predicts the respective qualifiers. In our experiment, we restricted the dataset to documents with the Heart Transplantation descriptor and we only used the PubMed abstracts. We trained binary classifiers to predict qualifiers of this descriptor using logistic regression with a tfidf vectorizer and a fine-tuned DistilBERT model. We carried out a small-scale evaluation of our models with the Mortality qualifier on a test set consisting of 30 articles (15 positives and 15 negatives). This test set was then manually re-annotated by a cardiac surgeon, expert in thoracic transplantation. On this re-annotated test set, we obtained macroaveraged F1 scores of 0.81 for the logistic regression model and of 0.85 for the DistilBERT model. Both scores are higher than the macroaveraged F1 score of 0.76 from the initial PubMed manual annotation. Our procedure would be easily extensible to all the MeSH descriptors with sufficient training data and, we believe, would enable human annotators to complete the indexing work more easily.Clinical Relevance-Selecting relevant articles is important for clinicians and researchers, but also often a challenge, especially in complex subspecialties such as heart transplantation. In this study, a machine-learning model outperformed PubMed's manual annotation, which is promising for improved quality in information retrieval.

Utility of heparin-binding protein following cardiothoracic surgery using cardiopulmonary bypass.

Cardiothoracic surgery using cardiopulmonary bypass (CPB) triggers an inflammatory state that may be difficult to differentiate from infection. Heparin-binding protein (HBP) is a candidate biomarker for sepsis. As data indicates that HBP normalizes rapidly after cardiothoracic surgery, it may be a suitable early marker of postoperative infection. We therefore aimed to investigate which variables influence postoperative HBP levels and whether elevated HBP concentration is associated with poor surgical outcome. This exploratory, prospective, observational study enrolled 1475 patients undergoing cardiothoracic surgery using CPB, where HBP was measured at ICU arrival. Patients with HBP in the highest tercile were compared to remaining patients. Multivariable logistic regressions were performed to identify factors predictive of elevated HBP and 30-day mortality. Overall median HBP was 30.0 ng/mL. Patients undergoing isolated CABG or surgery with CPB-duration ≤ 60 min had a median HBP of 24.9 ng/mL and 23.2 ng/mL, respectively. Independent predictors of elevated postoperative HBP included increased EuroSCORE, prolonged CPB-duration and high intraoperative temperature. Increased HBP was an independent predictor of 30-day mortality. This study confirms the promising characteristics of HBP as a biomarker for identification of postoperative sepsis, especially after routine procedures. Further studies are required to investigate whether HBP may detect postoperative infections.

Optimal timing of influenza vaccination among patients with acute myocardial infarction - Findings from the IAMI trial.

Influenza vaccination reduces the risk of adverse cardiovascular events.The IAMI trial randomly assigned 2571 patients with acute myocardial infarction (AMI) to receive influenza vaccine or saline placebo during their index hospital admission. It was conducted at 30 centers in 8 countries from October 1, 2016 to March 1, 2020. In this post-hoc exploratory sub-study, we compare the trial outcomes in patients receiving early season vaccination (n = 1188) and late season vaccination (n = 1344).The primary endpoint wasthe composite of all-cause death, myocardial infarction (MI), or stent thrombosis at 12 months. Thecumulative incidence of the primary and key secondary endpoints by randomized treatment and early or late vaccination was estimated using the Kaplan-Meier method. In the early vaccinated group, the primary composite endpoint occurred in 36 participants (6.0%) assigned to influenza vaccine and 49 (8.4%) assigned to placebo (HR 0.69; 95% CI 0.45 to 1.07), compared to 31 participants (4.7%) assigned to influenza vaccine and 42 (6.2%) assigned to placebo (HR 0.74; 95% CI 0.47 to 1.18) in the late vaccinated group (P = 0.848 for interaction on HR scale at 1 year). We observed similar estimates for the key secondary endpoints of all-cause death and CV death. There was no statistically significant difference in vaccine effectiveness against adverse cardiovascular events by timing of vaccination. The effect of vaccination on all-cause death at one year was more pronounced in the group receiving early vaccination (HR 0.50; 95% CI, 0.29 to 0.86) compared late vaccination group (HR 0.75; 35% CI, 0.40 to 1.40) but there was no statistically significant difference between these groups (Interaction P = 0.335). In conclusion,there is insufficient evidence from the trial to establish whether there is a difference in efficacy between early and late vaccinationbut regardless of vaccination timing we strongly recommend influenza vaccination in all patients with cardiovascular diseases.

Hyperglycemia and insulin infusion in pancreatoduodenectomy: a prospective cohort study on feasibility and impact on complications.

BACKGROUND: Hyperglycemia is a risk factor for postoperative complications but its impact on outcome after pancreatoduodenectomy (PD) is scarcely studied. This prospective cohort study aimed to assess the effect of continuous insulin infusion on postoperative complications and blood glucose, as well as to evaluate the impact of hyperglycemia on complications, after PD. MATERIALS AND METHODS: One hundred patients planned for PD at Skåne University Hospital, Sweden were prospectively included for perioperative continuous insulin infusion and a historic cohort of 100 patients was included retrospectively. Median blood glucose levels were calculated and data on complications were analyzed and compared between the historic cohort and the intervention group as well as between normo- and hyperglycemic patients. RESULTS: Median glucose levels were significantly lower in the intervention group compared to the historic cohort up to 30 days postoperatively (median glucose 8.5 mmol/l (interquartile range 6.4-11) vs. 9.1 mmol/l (interquartile range 6.8-17) ( P =0.007)). No significant differences in complication rates were recorded between these two groups. The incidence of complications classified as Clavien ≥3 was higher in hyperglycemic patients (100 vs. 27%, P =0.024). Among hyperglycemic patients the prevalence of preoperative diabetes was higher compared to normoglycemic patients (52 vs.12%, P <0.001). In patients with a known diagnosis of diabetes, a trend, although not statistically significant, towards a lower incidence of postoperative pancreatic fistula grade B and C, as well as postpancreatectomy hemorrhage grade B and C, was seen compared to those without preoperative diabetes (6.8 vs. 14%, P =0.231 and 2.3 vs. 7.0%, P =0.238, respectively). CONCLUSION: Insulin infusion in the early postoperative phase after PD is feasible in a non-ICU setting and significantly decreased blood glucose levels. The influence on complications was limited. Preoperative diabetes was a significant predictor of postoperative hyperglycemia and was associated with a lower incidence of clinically significant postoperative pancreatic fistula.

Reproducibility in ecology and evolution: Minimum standards for data and code.

We call for journals to commit to requiring open data be archived in a format that will be simple and clear for readers to understand and use. If applied consistently, these requirements will allow contributors to be acknowledged for their work through citation of open data, and facilitate scientific progress.

Exploring Spatial Heterogeneity of Immune Cells in Nasopharyngeal Cancer.

Nasopharyngeal cancer (NPC) is a malignant tumor. In a recent publication, we described the presence and distribution of CD8+ T cells in NPC and used the information to identify 'inflamed', 'immune-excluded', and 'desert' immune phenotypes, where 'inflamed' and 'immune-excluded' NPCs were correlated with CD8 T cell infiltration and survival. Arguably, more detailed and, in particular, spatially resolved data are required for patient stratification and for the identification of new treatment targets. In this study, we investigate the phenotype of CD45+ leukocytes in the previously analyzed NPC samples by applying multiplexed tissue analysis to assess the spatial distribution of cell types and to quantify selected biomarkers. A total of 47 specified regions-of-interest (ROIs) were generated based on CD45, CD8, and PanCK morphological staining. Using the GeoMx® Digital Spatial Profiler (DSP), 49 target proteins were digitally quantified from the selected ROIs of a tissue microarray consisting of 30 unique NPC biopsies. Protein targets associated with B cells (CD20), NK cells (CD56), macrophages (CD68), and regulatory T cells (PD-1, FOXP3) were most differentially expressed in CD45+ segments within 'immune-rich cancer cell islet' regions of the tumor (cf. 'surrounding stromal leukocyte' regions). In contrast, markers associated with suppressive populations of myeloid cells (CD163, B7-H3, VISTA) and T cells (CD4, LAG3, Tim-3) were expressed at a higher level in CD45+ segments in the 'surrounding stromal leukocyte' regions (cf. 'immune-rich cancer cell islet' regions). When comparing the three phenotypes, the 'inflamed' profile (cf. 'immune-excluded' and 'desert') exhibited higher expression of markers associated with B cells, NK cells, macrophages, and myeloid cells. Myeloid markers were highly expressed in the 'immune-excluded' phenotype. Granulocyte markers and immune-regulatory markers were higher in the 'desert' profile (cf. 'inflamed' and 'immune-excluded'). In conclusion, this study describes the spatial heterogeneity of the immune microenvironment in NPC and highlights immune-related biomarkers in immune phenotypes, which may aid in the stratification of patients for therapeutic purposes.

Thermoregulatory costs of the innate immune response are modulated by winter food availability in a small passerine.

In winter, a challenge to the immune system could pose a major energetic trade-off for small endotherms, whereby increasing body temperature (Tb ; i.e. eliciting fever) may be beneficial to fight off invading pathogens yet incur a cost for vital energy-saving mechanisms. Having previously shown that the availability and acquisition of energy, through manipulation of food predictability, influences the depth of rest-phase hypothermia in a wild bird in winter, we expected that the nocturnal thermoregulatory component of the acute-phase immune response would also be modulated by food availability. By manipulating winter food availability in the wild for great tits Parus major, we created an area offering a "predictable" and constant supply of food at feeding stations, while an unmanipulated area was subject to naturally "unpredictable" food. Birds were subject to an immune challenge shortly after dusk, and the thermoregulatory response was quantified via continuous recording of nocturnal Tb , using subcutaneous thermo-sensitive transponders. In response to immune challenge, all birds increased Tb above the level maintained prior to immune challenge (i.e. baseline). However, birds experiencing a naturally unpredictable food supply elevated Tb more than birds subject to predictable food resources, during the period of expected peak response and for the duration of the night. Furthermore, "unpredictable-food" females took longer to return to their baseline Tb . Assuming baseline nocturnal Tb reflects an individual's optimum, based on their available energy budget, the metabolic cost of eliciting an acute-phase response for "unpredictable-food" birds was more than double that of "predictable-food" birds. The absence of differences in absolute Tb during the peak response could support the idea of an optimal Tb for immune system activation. Alternatively, "predictable-food" birds could have acquired tolerance to endotoxin as a result of using feeding stations, thus affording them reduced costs associated with a smaller Tb increase. These findings shed new light on the trade-offs associated with food acquisition, thermoregulation and immune function in small-bodied endotherms. This knowledge is of increasing importance, given the predicted elevated pathogen risks associated with changes in climate and anthropogenic activities.

Interactive effects of rising temperatures and urbanisation on birds across different climate zones: A mechanistic perspective.

Climate change and urbanisation are among the most pervasive and rapidly growing threats to biodiversity worldwide. However, their impacts are usually considered in isolation, and interactions are rarely examined. Predicting species' responses to the combined effects of climate change and urbanisation, therefore, represents a pressing challenge in global change biology. Birds are important model taxa for exploring the impacts of both climate change and urbanisation, and their behaviour and physiology have been well studied in urban and non-urban systems. This understanding should allow interactive effects of rising temperatures and urbanisation to be inferred, yet considerations of these interactions are almost entirely lacking from empirical research. Here, we synthesise our current understanding of the potential mechanisms that could affect how species respond to the combined effects of rising temperatures and urbanisation, with a focus on avian taxa. We discuss potential interactive effects to motivate future in-depth research on this critically important, yet overlooked, aspect of global change biology. Increased temperatures are a pronounced consequence of both urbanisation (through the urban heat island effect) and climate change. The biological impact of this warming in urban and non-urban systems will likely differ in magnitude and direction when interacting with other factors that typically vary between these habitats, such as resource availability (e.g. water, food and microsites) and pollution levels. Furthermore, the nature of such interactions may differ for cities situated in different climate types, for example, tropical, arid, temperate, continental and polar. Within this article, we highlight the potential for interactive effects of climate and urban drivers on the mechanistic responses of birds, identify knowledge gaps and propose promising future research avenues. A deeper understanding of the behavioural and physiological mechanisms mediating species' responses to urbanisation and rising temperatures will provide novel insights into ecology and evolution under global change and may help better predict future population responses.

A machine learning model for prediction of 30-day primary graft failure after heart transplantation.

Background: Primary graft failure (PGF) remains the most common cause of short-term mortality after heart transplantation. The main objective was to develop and validate a risk model for prediction of short-term mortality due to PGF after heart transplantation using the ISHLT Heart Transplant Registry. Methods: We developed a non-linear artificial neural networks (ANN) model to evaluate the association between recipient-donor variables and post-transplant PGF. Patients in the ISHLT registry were randomly divided into derivation and an independent internal validation cohort. The primary endpoint was PGF defined as death within 30 days due to Graft failure or Cardiovascular causes or retransplant within 30 days for causes other than rejection. Results: Among 64,964 adult recipients transplanted between 1994 and 2013, mean age was 51 years and 22% were female. The incidence of PGF up to 30 days was 3.7%. The ANN model selected 33 of 77 risk variables as relevant for PGF prediction. The C-index in the test cohort was 0.70 (95% CI: 0.68-0.71). The risk variables which most influenced the PGF were underlying HF diagnosis, ischemia time and sex, while renal function had a lower influence. Conclusion: An ANN model to predict primary graft dysfunction was derived and independently validated. The good discrimination of the ANN model likely results from its flexibility to model potentially non-linear relationships and interactions. Whether this model with improved discrimination can assist in clinical decisions at the time of transplant should be tested.

Clinical impact of influenza vaccination after ST- and non-ST-segment elevation myocardial infarction - insights from the IAMI trial.

BACKGROUND: Influenza vaccination early after myocardial infarction (MI) improves prognosis but vaccine effectiveness may differ dependent on type of MI. METHODS: A total of 2,571 participants were prospectively enrolled in the Influenza vaccination after myocardial infarction (IAMI) trial and randomly assigned to receive in-hospital inactivated influenza vaccine or saline placebo. The trial was conducted at 30 centers in eight countries from October 1, 2016 to March 1, 2020. Here we report vaccine effectiveness in the 2,467 participants with ST-segment elevation MI (STEMI, n = 1,348) or non-ST-segment elevation MI (NSTEMI, n = 1,119). The primary endpoint was the composite of all-cause death, MI, or stent thrombosis at 12 months. Cumulative incidence of the primary and key secondary endpoints by randomized treatment and NSTEMI/STEMI was estimated using the Kaplan-Meier method. Treatment effects were evaluated with formal interaction testing to assess for effect modification. RESULTS: Baseline risk was higher in participants with NSTEMI. In the NSTEMI group the primary endpoint occurred in 6.5% of participants assigned to influenza vaccine and 10.5% assigned to placebo (hazard ratio [HR], 0.60; 95% CI, 0.39-0.91), compared to 4.1% assigned to influenza vaccine and 4.5% assigned to placebo in the STEMI group (HR, 0.90; 95% CI, 0.54-1.50, P = .237 for interaction). Similar findings were seen for the key secondary endpoints of all-cause death and cardiovascular death. The Kaplan-Meier risk difference in all-cause death at one year was more pronounced in participants with NSTEMI (NSTEMI: HR, 0.47; 95% CI 0.28-0.80, STEMI: HR, 0.86; 95% CI, 0.43-1.70, interaction P = .028). CONCLUSIONS: The beneficial effect of influenza vaccination on adverse cardiovascular events may be enhanced in patients with NSTEMI compared to those with STEMI.

Enhanced survival prediction using explainable artificial intelligence in heart transplantation.

The most limiting factor in heart transplantation is the lack of donor organs. With enhanced prediction of outcome, it may be possible to increase the life-years from the organs that become available. Applications of machine learning to tabular data, typical of clinical decision support, pose the practical question of interpretation, which has technical and potential ethical implications. In particular, there is an issue of principle about the predictability of complex data and whether this is inherent in the data or strongly dependent on the choice of machine learning model, leading to the so-called accuracy-interpretability trade-off. We model 1-year mortality in heart transplantation data with a self-explaining neural network, which is benchmarked against a deep learning model on the same development data, in an external validation study with two data sets: (1) UNOS transplants in 2017-2018 (n = 4750) for which the self-explaining and deep learning models are comparable in their AUROC 0.628 [0.602,0.654] cf. 0.635 [0.609,0.662] and (2) Scandinavian transplants during 1997-2018 (n = 2293), showing good calibration with AUROCs of 0.626 [0.588,0.665] and 0.634 [0.570, 0.698], respectively, with and without missing data (n = 982). This shows that for tabular data, predictive models can be transparent and capture important nonlinearities, retaining full predictive performance.