MesoGraph: Automatic profiling of mesothelioma subtypes from histological images.

Mesothelioma is classified into three histological subtypes, epithelioid, sarcomatoid, and biphasic, according to the relative proportions of epithelioid and sarcomatoid tumor cells present. Current guidelines recommend that the sarcomatoid component of each mesothelioma is quantified, as a higher percentage of sarcomatoid pattern in biphasic mesothelioma shows poorer prognosis. In this work, we develop a dual-task graph neural network (GNN) architecture with ranking loss to learn a model capable of scoring regions of tissue down to cellular resolution. This allows quantitative profiling of a tumor sample according to the aggregate sarcomatoid association score. Tissue is represented by a cell graph with both cell-level morphological and regional features. We use an external multicentric test set from Mesobank, on which we demonstrate the predictive performance of our model. We additionally validate our model predictions through an analysis of the typical morphological features of cells according to their predicted score.

Malignant Mesothelioma subtyping via sampling driven multiple instance prediction on tissue image and cell morphology data.

Malignant Mesothelioma is a difficult to diagnose and highly lethal cancer usually associated with asbestos exposure. It can be broadly classified into three subtypes: Epithelioid, Sarcomatoid, and a hybrid Biphasic subtype in which significant components of both of the previous subtypes are present. Early diagnosis and identification of the subtype informs treatment and can help improve patient outcome. However, the subtyping of malignant mesothelioma, and specifically the recognition of transitional features from routine histology slides has a high level of inter-observer variability. In this work, we propose an end-to-end multiple instance learning (MIL) approach for malignant mesothelioma subtyping. This uses an adaptive instance-based sampling scheme for training deep convolutional neural networks on bags of image patches that allows learning on a wider range of relevant instances compared to max or top-N based MIL approaches. We also investigate augmenting the instance representation to include aggregate cellular morphology features from cell segmentation. The proposed MIL approach enables identification of malignant mesothelial subtypes of specific tissue regions. From this a continuous characterisation of a sample according to predominance of sarcomatoid vs epithelioid regions is possible, thus avoiding the arbitrary and highly subjective categorisation by currently used subtypes. Instance scoring also enables studying tumor heterogeneity and identifying patterns associated with different subtypes. We have evaluated the proposed method on a dataset of 234 tissue micro-array cores with an AUROC of 0.89±0.05 for this task. The dataset and developed methodology is available for the community at: https://github.com/measty/PINS.

Inflammation and vascular remodeling in COVID-19 hearts.

A wide range of cardiac symptoms have been observed in COVID-19 patients, often significantly influencing the clinical outcome. While the pathophysiology of pulmonary COVID-19 manifestation has been substantially unraveled, the underlying pathomechanisms of cardiac involvement in COVID-19 are largely unknown. In this multicentre study, we performed a comprehensive analysis of heart samples from 24 autopsies with confirmed SARS-CoV-2 infection and compared them to samples of age-matched Influenza H1N1 A (n = 16), lymphocytic non-influenza myocarditis cases (n = 8), and non-inflamed heart tissue (n = 9). We employed conventional histopathology, multiplexed immunohistochemistry (MPX), microvascular corrosion casting, scanning electron microscopy, X-ray phase-contrast tomography using synchrotron radiation, and direct multiplexed measurements of gene expression, to assess morphological and molecular changes holistically. Based on histopathology, none of the COVID-19 samples fulfilled the established diagnostic criteria of viral myocarditis. However, quantification via MPX showed a significant increase in perivascular CD11b/TIE2 + -macrophages in COVID-19 over time, which was not observed in influenza or non-SARS-CoV-2 viral myocarditis patients. Ultrastructurally, a significant increase in intussusceptive angiogenesis as well as multifocal thrombi, inapparent in conventional morphological analysis, could be demonstrated. In line with this, on a molecular level, COVID-19 hearts displayed a distinct expression pattern of genes primarily coding for factors involved in angiogenesis and epithelial-mesenchymal transition (EMT), changes not seen in any of the other patient groups. We conclude that cardiac involvement in COVID-19 is an angiocentric macrophage-driven inflammatory process, distinct from classical anti-viral inflammatory responses, and substantially underappreciated by conventional histopathologic analysis. For the first time, we have observed intussusceptive angiogenesis in cardiac tissue, which we previously identified as the linchpin of vascular remodeling in COVID-19 pneumonia, as a pathognomic sign in affected hearts. Moreover, we identified CD11b + /TIE2 + macrophages as the drivers of intussusceptive angiogenesis and set forward a putative model for the molecular regulation of vascular alterations.

Genetic Architecture of Acute Myocarditis and the Overlap With Inherited Cardiomyopathy.

BACKGROUND: Acute myocarditis is an inflammatory condition that may herald the onset of dilated cardiomyopathy (DCM) or arrhythmogenic cardiomyopathy (ACM). We investigated the frequency and clinical consequences of DCM and ACM genetic variants in a population-based cohort of patients with acute myocarditis. METHODS: This was a population-based cohort of 336 consecutive patients with acute myocarditis enrolled in London and Maastricht. All participants underwent targeted DNA sequencing for well-characterized cardiomyopathy-associated genes with comparison to healthy controls (n=1053) sequenced on the same platform. Case ascertainment in England was assessed against national hospital admission data. The primary outcome was all-cause mortality. RESULTS: Variants that would be considered pathogenic if found in a patient with DCM or ACM were identified in 8% of myocarditis cases compared with <1% of healthy controls (P=0.0097). In the London cohort (n=230; median age, 33 years; 84% men), patients were representative of national myocarditis admissions (median age, 32 years; 71% men; 66% case ascertainment), and there was enrichment of rare truncating variants (tv) in ACM-associated genes (3.1% of cases versus 0.4% of controls; odds ratio, 8.2; P=0.001). This was driven predominantly by DSP-tv in patients with normal LV ejection fraction and ventricular arrhythmia. In Maastricht (n=106; median age, 54 years; 61% men), there was enrichment of rare truncating variants in DCM-associated genes, particularly TTN-tv, found in 7% (all with left ventricular ejection fraction <50%) compared with 1% in controls (odds ratio, 3.6; P=0.0116). Across both cohorts over a median of 5.0 years (interquartile range, 3.9-7.8 years), all-cause mortality was 5.4%. Two-thirds of deaths were cardiovascular, attributable to worsening heart failure (92%) or sudden cardiac death (8%). The 5-year mortality risk was 3.3% in genotype-negative patients versus 11.1% for genotype-positive patients (Padjusted=0.08). CONCLUSIONS: We identified DCM- or ACM-associated genetic variants in 8% of patients with acute myocarditis. This was dominated by the identification of DSP-tv in those with normal left ventricular ejection fraction and TTN-tv in those with reduced left ventricular ejection fraction. Despite differences between cohorts, these variants have clinical implications for treatment, risk stratification, and family screening. Genetic counseling and testing should be considered in patients with acute myocarditis to help reassure the majority while improving the management of those with an underlying genetic variant.

Vascular histopathology and connective tissue ultrastructure in spontaneous coronary artery dissection: pathophysiological and clinical implications.

AIMS: Spontaneous coronary artery dissection (SCAD) is a cause of acute coronary syndromes and in rare cases sudden cardiac death (SCD). Connective tissue abnormalities, coronary inflammation, increased coronary vasa vasorum (VV) density, and coronary fibromuscular dysplasia have all been implicated in the pathophysiology of SCAD but have not previously been systematically assessed. We designed a study to investigate the coronary histological and dermal collagen ultrastructural findings in SCAD. METHODS AND RESULTS: Thirty-six autopsy SCAD cases were compared with 359 SCAD survivors. Coronary and myocardial histology and immunohistochemistry were undertaken. Transmission electron microscopy (TEM) of dermal extracellular matrix (ECM) components of n = 31 SCAD survivors and n = 16 healthy volunteers were compared. Autopsy cases were more likely male (19% vs. 5%; P = 0.0004) with greater proximal left coronary involvement (56% vs. 18%; P < 0.0001) compared to SCAD survivors. N = 24 (66%) of cases showed no myocardial infarction on macro- or microscopic examination consistent with arrhythmogenic death. There was significantly (P < 0.001) higher inflammation in cases with delayed-onset death vs. sudden death and significantly more inflammation surrounding the dissected vs. non-dissected vessel segments. N = 17 (47%) cases showed limited intimal fibro-elastic thickening but no features of fibromuscular dysplasia and no endothelial or internal elastic lamina abnormalities. There were no differences in VV density between SCAD and control cases. TEM revealed no general ultrastructural differences in ECM components or markers of fibroblast metabolic activity. CONCLUSIONS: Assessment of SCD requires careful exclusion of SCAD, particularly in cases without myocardial necrosis. Peri-coronary inflammation in SCAD is distinct from vasculitides and likely a reaction to, rather than a cause for SCAD. Coronary fibromuscular dysplasia or increased VV density does not appear pathophysiologically important. Dermal connective tissue changes are not common in SCAD survivors.

A case with two faces: noncompaction or phospholamban cardiomyopathy?

Noncompaction cardiomyopathy is a well-known clinical entity, whereas phospholamban gene mutation is a relatively recently known mutation with phenotypes as arrhythmogenic cardiomyopathy and dilated cardiomyopathy. We report the case of a 15-year-old girl that presents with rapid progressive heart failure based on a noncompaction cardiomyopathy as confirmed through cardiovascular imaging. As a result of her progressive heart failure 22 months later she received a heart transplant. Genetic testing showed a phospholamban gene mutation. We present cardiovascular images together with macroscopic and microscopic anatomy. This case shows the importance of considering phospholamban gene mutation in a case of severe noncompaction cardiomyopathy.

Artificial intelligence in the diagnosis and management of arrhythmias.

The field of cardiac electrophysiology (EP) had adopted simple artificial intelligence (AI) methodologies for decades. Recent renewed interest in deep learning techniques has opened new frontiers in electrocardiography analysis including signature identification of diseased states. Artificial intelligence advances coupled with simultaneous rapid growth in computational power, sensor technology, and availability of web-based platforms have seen the rapid growth of AI-aided applications and big data research. Changing lifestyles with an expansion of the concept of internet of things and advancements in telecommunication technology have opened doors to population-based detection of atrial fibrillation in ways, which were previously unimaginable. Artificial intelligence-aided advances in 3D cardiac imaging heralded the concept of virtual hearts and the simulation of cardiac arrhythmias. Robotics, completely non-invasive ablation therapy, and the concept of extended realities show promise to revolutionize the future of EP. In this review, we discuss the impact of AI and recent technological advances in all aspects of arrhythmia care.

ATGL Deficiency-Induced Triglyceride Deposit Cardiomyovasculopathy Requiring Heart Transplant: A 5-Year Follow-Up.

A young man presented with syncope. He was diagnosed with triglyceride deposit cardiomyovasculopathy and skeletal myopathy secondary to adipose triglyceride lipase (ATGL) deficiency. Despite optimal medical therapy, he required heart transplantation to treat his heart failure. Five years post-transplant, the graft function was normal with no evidence of triglyceride deposits. (Level of Difficulty: Intermediate.).

Early Insight Into In Vivo Recellularization of Cell-Free Allogenic Heart Valves.

BACKGROUND: Unlike the vast amount of animal data available on the recellularization of allogenic decellularized heart valves (DHVs), there have only been sporadic histologic reports on such grafts in humans. METHODS: Two experienced cardiac pathologists independently evaluated human specimens obtained during reoperation between December 2010 and April 2017 DHVs in seven categories after automated staining (scores: 0 to 6) in comparison with published data. An optimal result of 42 points was classified as 100%. RESULTS: We found that 364 DHVs, 236 decellularized pulmonary homografts (DPHs), and 128 decellularized aortic homografts (DAHs) were implanted, and freedom from explantation was 96.1% (DAH) and 98.7% (DPH). Reoperations were because of (suspected) endocarditis in 5 of 11 patients, stenosis at the subvalvular or valvular or supravalvular level in 3 of 11 patients, planned staged reoperation in 2 of 11 patients, and 1 heart transplantation. Good reader agreement was reflected by an interagreement weighted κ of 0.783 (95% confidence interval: 0.707 to 0.859). The relative histologic score in nonendocarditis specimens was 76% ± 4.3% (maximum 81%). Intracellular procollagen type 1 production was found in recipient mesenchymal cells within the transplanted grafts. In endocarditis specimens the histologic score was significantly lower with 48% ± 7.3% (minimum 41%, p = 0.0004) because of leucocyte infiltration and matrix degradation. One DPH showed immune system-mediated graft failure. Grafts obtained during the first 12 months after implantation were not evenly repopulated with less recellularization in the inner parts; no difference was found between DAH and DPH with respect to extent of recellularization. CONCLUSIONS: Substantial in vivo recellularization with noninflammatory cells was observed in this study. Spontaneous recellularization appears to require multiple months, which correspondingly has an impact on size selection for growing patients.

Sudden Death and Left Ventricular Involvement in Arrhythmogenic Cardiomyopathy.

BACKGROUND: Arrhythmogenic cardiomyopathy (ACM) is an inherited heart muscle disorder characterized by myocardial fibrofatty replacement and an increased risk of sudden cardiac death (SCD). Originally described as a right ventricular disease, ACM is increasingly recognized as a biventricular entity. We evaluated pathological, genetic, and clinical associations in a large SCD cohort. METHODS: We investigated 5205 consecutive cases of SCD referred to a national cardiac pathology center between 1994 and 2018. Hearts and tissue blocks were examined by expert cardiac pathologists. After comprehensive histological evaluation, 202 cases (4%) were diagnosed with ACM. Of these, 15 (7%) were diagnosed antemortem with dilated cardiomyopathy (n=8) or ACM (n=7). Previous symptoms, medical history, circumstances of death, and participation in competitive sport were recorded. Postmortem genetic testing was undertaken in 24 of 202 (12%). Rare genetic variants were classified according to American College of Medical Genetics and Genomics criteria. RESULTS: Of 202 ACM decedents (35.4±13.2 years; 82% male), no previous cardiac symptoms were reported in 157 (78%). Forty-one decedents (41/202; 20%) had been participants in competitive sport. The adjusted odds of dying during physical exertion were higher in men than in women (odds ratio, 4.58; 95% CI, 1.54-13.68; P=0.006) and in competitive athletes in comparison with nonathletes (odds ratio, 16.62; 95% CI, 5.39-51.24; P<0.001). None of the decedents with an antemortem diagnosis of dilated cardiomyopathy fulfilled definite 2010 Task Force criteria. The macroscopic appearance of the heart was normal in 40 of 202 (20%) cases. There was left ventricular histopathologic involvement in 176 of 202 (87%). Isolated right ventricular disease was seen in 13%, isolated left ventricular disease in 17%, and biventricular involvement in 70%. Among whole hearts, the most common areas of fibrofatty infiltration were the left ventricular posterobasal (68%) and anterolateral walls (58%). Postmortem genetic testing yielded pathogenic variants in ACM-related genes in 6 of 24 (25%) decedents. CONCLUSIONS: SCD attributable to ACM affects men predominantly, most commonly occurring during exertion in athletic individuals in the absence of previous reported cardiac symptoms. Left ventricular involvement is observed in the vast majority of SCD cases diagnosed with ACM at autopsy. Current Task Force criteria may fail to diagnose biventricular ACM before death.

Initial 2-year results of CardioCel® patch implantation in children.

OBJECTIVES: We present the initial 2-year results of CardioCel® patch (Admedus Regen Pty Ltd, Perth, WA, Australia) implantation in paediatric patients with congenital heart diseases. METHODS: This was a single-centre retrospective study with prospectively collected data of all patients aged 18 years and under operated for congenital heart disease. The patch was introduced in 2014, with clinical practice committee approval and a special consent in case of an Ozaki procedure. Standard follow-up was performed with systematic clinical exams and echocardiograms. In case of reoperation or graft failure, the patch was removed and sent for a histological examination. RESULTS: Between March 2014 and April 2016, 101 patients had surgical repair using a CardioCel patch. The mean age was 22 (±36.3) months, and the mean weight was 9.7 (±10.3) kg. No infections and no intraoperative implantation difficulties were associated with the patch. The median follow-up period was 212 (range 4-726) days. The overall 30-day postoperative mortality was 3.8% (n = 4), none of which were related to graft failure. Five children were reoperated because of graft failure, 4 of whom had the patch implanted for aortic and were aged less than 10 days. The indications for patch implantation in the aortic position were aortopulmonary window, truncus arteriosus, coarctation and aortic arch hypoplasia repair. The median time between the first and the second operation for graft failure was 245 (range 5-480) days. CONCLUSIONS: Our experience shows that the patch is well tolerated in the septal, valvar and pulmonary artery positions. However, we experienced graft failures in infants in the aortic position.

Acute fulminant necrotizing eosinophilic myocarditis: early diagnosis and treatment.

Necrotizing eosinophilic myocarditis is a rare but potentially fatal condition that requires prompt recognition and treatment. We describe a case of a young athlete presenting with chest pain and breathlessness, with evidence of rapidly deteriorating cardiac function. The condition was successfully treated with corticosteroids, with no evidence of residual myocardial damage. This is the first reported case to demonstrate the utility of cardiac magnetic resonance imaging for diagnosis and monitoring response to treatment. It also highlights the value of endomyocardial biopsy in establishing a tissue diagnosis in cases of fulminant myocarditis, in order to direct treatment appropriately.

Histologically Proven Myocardial Carcinoid Metastases: The Value of Multimodality Imaging.

We present a case of a patient with intramyocardial metastases from a carcinoid tumor. These findings were detected using cardiovascular magnetic resonance imaging, with functional metabolic activity analyzed using nuclear imaging and confirmed by histologic findings at surgical biopsy. This case highlights the value of cardiovascular magnetic resonance imaging and the importance of multimodality imaging.

Airway remodelling in the transplanted lung.

Following lung transplantation, fibrotic remodelling of the small airways has been recognized for almost 5 decades as the main correlate of chronic graft failure and a major obstacle to long-term survival. Mainly due to airway fibrosis, pulmonary allografts currently show the highest attrition rate of all solid organ transplants, with a 5-year survival rate of 58 % on a worldwide scale. The observation that these morphological changes are not just the hallmark of chronic rejection but rather represent a manifestation of a multitude of alloimmune-dependent and -independent injuries was made more recently, as was the discovery that chronic lung allograft dysfunction manifests in different clinical phenotypes of respiratory impairment and corresponding morphological subentities. Although recent years have seen considerable advances in identifying and categorizing these subgroups on the basis of clinical, functional and histomorphological changes, as well as susceptibility to medicinal treatment, this process is far from over. Since the actual pathophysiological mechanisms governing airway remodelling are still only poorly understood, diagnosis and therapy of chronic lung allograft dysfunction presents a major challenge to clinicians, radiologists and pathologists alike. Here, we review and discuss the current state of the literature on chronic lung allograft dysfunction and shed light on classification systems, corresponding clinical and morphological changes, key cellular players and underlying molecular pathways, as well as on emerging diagnostic and therapeutic approaches.

Etiology of Sudden Death in Sports: Insights From a United Kingdom Regional Registry.

BACKGROUND: Accurate knowledge of causes of sudden cardiac death (SCD) in athletes and its precipitating factors is necessary to establish preventative strategies. OBJECTIVES: This study investigated causes of SCD and their association with intensive physical activity in a large cohort of athletes. METHODS: Between 1994 and 2014, 357 consecutive cases of athletes who died suddenly (mean 29 ± 11 years of age, 92% males, 76% Caucasian, 69% competitive) were referred to our cardiac pathology center. All subjects underwent detailed post-mortem evaluation, including histological analysis by an expert cardiac pathologist. Clinical information was obtained from referring coroners. RESULTS: Sudden arrhythmic death syndrome (SADS) was the most prevalent cause of death (n = 149 [42%]). Myocardial disease was detected in 40% of cases, including idiopathic left ventricular hypertrophy (LVH) and/or fibrosis (n = 59, 16%); arrhythmogenic right ventricular cardiomyopathy (ARVC) (13%); and hypertrophic cardiomyopathy (HCM) (6%). Coronary artery anomalies occurred in 5% of cases. SADS and coronary artery anomalies affected predominantly young athletes (≤ 35 years of age), whereas myocardial disease was more common in older individuals. SCD during intense exertion occurred in 61% of cases; ARVC and left ventricular fibrosis most strongly predicted SCD during exertion. CONCLUSIONS: Conditions predisposing to SCD in sports demonstrate a significant age predilection. The strong association of ARVC and left ventricular fibrosis with exercise-induced SCD reinforces the need for early detection and abstinence from intense exercise. However, almost 40% of athletes die at rest, highlighting the need for complementary preventive strategies.

AT1-receptor blockade, but not renin inhibition, reduces aneurysm growth and cardiac failure in fibulin-4 mice.

AIMS: Increasing evidence supports a role for the angiotensin II-AT1-receptor axis in aneurysm development. Here, we studied whether counteracting this axis via stimulation of AT2 receptors is beneficial. Such stimulation occurs naturally during AT1-receptor blockade with losartan, but not during renin inhibition with aliskiren. METHODS AND RESULTS: Aneurysmal homozygous fibulin-4 mice, displaying a four-fold reduced fibulin-4 expression, were treated with placebo, losartan, aliskiren, or the ß-blocker propranolol from day 35 to 100. Their phenotype includes cystic media degeneration, aortic regurgitation, left ventricular dilation, reduced ejection fraction, and fractional shortening. Although losartan and aliskiren reduced hemodynamic stress and increased renin similarly, only losartan increased survival. Propranolol had no effect. No drug rescued elastic fiber fragmentation in established aneurysms, although losartan did reduce aneurysm size. Losartan also increased ejection fraction, decreased LV diameter, and reduced cardiac pSmad2 signaling. None of these effects were seen with aliskiren or propranolol. Longitudinal micro-CT measurements, a novel method in which each mouse serves as its own control, revealed that losartan reduced LV growth more than aneurysm growth, presumably because the heart profits both from the local (cardiac) effects of losartan and its effects on aortic root remodeling. CONCLUSION: Losartan, but not aliskiren or propranolol, improved survival in fibulin-4 mice. This most likely relates to its capacity to improve structure and function of both aorta and heart. The absence of this effect during aliskiren treatment, despite a similar degree of blood pressure reduction and renin-angiotensin system blockade, suggests that it might be because of AT2-receptor stimulation.

Intratumoral macrophage phenotype and CD8+ T lymphocytes as potential tools to predict local tumor outgrowth at the intervention site in malignant pleural mesothelioma.

OBJECTIVES: In patients with malignant pleural mesothelioma (MPM), local tumor outgrowth (LTO) after invasive procedures is a well-known complication. Currently, no biomarker is available to predict the occurrence of LTO. This study aims to investigate whether the tumor macrophage infiltration and phenotype of and/or the infiltration of CD8+ T-cells predicts LTO. MATERIALS AND METHODS: Ten mesothelioma patients who developed LTO were clinically and pathologically matched with 10 non-LTO mesothelioma patients. Immunohistochemistry was performed on diagnostic biopsies to determine the total TAM (CD68), the M2 TAM (CD163) and CD8+ T-cell count (CD8). RESULTS: The mean M2/total TAM ratio differed between the two groups: 0.90±0.09 in the LTO group versus 0.63±0.09 in patients without LTO (p<0.001). In addition, the mean CD8+ T-cell count was significantly different between the two groups: 30 per 0.025 cm2 (range 2-60) in the LTO group and 140 per 0.025 cm2 (range 23-314) in the patients without LTO (p<0.01). CONCLUSION: This study shows that patients who develop LTO after a local intervention have a higher M2/total TAM ratio and lower CD8+ cell count at diagnosis compared to patients who did not develop this outgrowth. We propose that the M2/total TAM ratio and the CD8+ T-cell amount are potential tools to predict which MPM patients are prone to develop LTO.