In this survey study of institutions across the US, marked variability in evaluation, treatment, and follow-up of adolescents 12 through 18 years of age with mRNA COVID-19 vaccine-associated myopericarditis (VAM) was noted. Only one adolescent with life-threatening complications was reported with no deaths at any of the participating institutions.

e Current European Commission (EC) surveillance regulations require discriminatory testing of all transmissible spongiform encephalopathy (TSE)-positive small ruminant (SR) samples in order to classify them as bovine spongiform encephalopathy (BSE) or non-BSE. This requires a range of tests, including characterization by bioassay in mouse models. Since 2005, naturally occurring BSE has been identified in two goats. It has also been demonstrated that more than one distinct TSE strain can coinfect a single animal in natural field situations. This study assesses the ability of the statutory methods as listed in the regulation to identify BSE in a blinded series of brain samples, in which ovine BSE and distinct isolates of scrapie are mixed at various ratios ranging from 99% to 1%. Additionally, these current statutory tests were compared with a new in vitro discriminatory method, which uses serial protein misfolding cyclic amplification (sPMCA). Western blotting consistently detected 50% BSE within a mixture, but at higher dilutions it had variable success. The enzyme-linked immunosorbent assay (ELISA) method consistently detected BSE only when it was present as 99% of the mixture, with variable success at higher dilutions. Bioassay and sPMCA reported BSE in all samples where it was present, down to 1%. sPMCA also consistently detected the presence of BSE in mixtures at 0.1%. While bioassay is the only validated method that allows comprehensive phenotypic characterization of an unknown TSE isolate, the sPMCA assay appears to offer a fast and cost-effective alternative for the screening of unknown isolates when the purpose of the investigation was solely to determine the presence or absence of BSE.

The in vitro amplification of prions by serial protein misfolding cyclic amplification has been shown to detect PrPSc to levels at least as sensitive as rodent bioassay but in a fraction of the time. Bovine spongiform encephalopathy is a zoonotic prion disease in cattle and has been shown to occur in 3 distinct forms, classical BSE (C-BSE) and 2 atypical BSE forms (L-BSE and H-BSE). Atypical forms are usually detected in asymptomatic, older cattle and are suggested to be spontaneous forms of the disease. Here, we show the development of a serial protein misfolding cyclic amplification method for the detection of H-BSE. The assay could detect PrPSc from 3 distinct experimental isolates of H-BSE, could detect PrPSc in as little as 1×10−12 g of brain material and was highly specific. Additionally, the product of serial protein misfolding cyclic amplification at all dilutions of seed analyzed could be readily distinguished from L-BSE, which did not amplify, and C-BSE, which had PrPSc with distinct protease K-resistance and protease K-resistant PrPSc molecular weights.

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To understand the possible role of mixed-prion infections in disease presentation, the current study reports the co-infection of sheep with bovine spongiform encephalopathy (BSE) and scrapie. The bovine BSE agent was inoculated subcutaneously into sheep with ARQ/ARQ or VRQ/ARQ PRNP genotypes either at the same time as subcutaneous challenge with scrapie, or three months later. In addition, VRQ/VRQ sheep naturally infected with scrapie after being born into a scrapie-affected flock were challenged subcutaneously with BSE at eight or twenty one months-of-age. Sheep were analysed by incubation period/attack rate, and western blot of brain tissue determined the presence of BSE or scrapie-like PrPSc. Serial protein misfolding cyclic amplification (sPMCA) that can detect very low levels of BSE in the presence of an excess of scrapie agent was also applied to brain and lymphoreticular tissue. For VRQ/ARQ sheep challenged with mixed infections, scrapie-like incubation periods were produced, and no BSE agent was detected. However, whilst ARQ/ARQ sheep developed disease with BSE-like incubation periods, some animals had a dominant scrapie western blot phenotype in brain, but BSE was detected in these sheep by sPMCA. In addition, VRQ/VRQ animals challenged with BSE after natural exposure to scrapie had scrapie-like incubation periods and dominant scrapie PrPSc in brain, but one sheep had BSE detectable by sPMCA in the brain. Overall, the study demonstrates for the first time that for scrapie/BSE mixed infections, VRQ/ARQ sheep with experimental scrapie did not propagate BSE but VRQ/VRQ sheep with natural scrapie could propagate low levels of BSE, and whilst BSE readily propagated in ARQ/ARQ sheep it was not always the dominant PrPSc strain in brain tissue. Indeed, for several animals, a dominant scrapie biochemical phenotype in brain did not preclude the presence of BSE prion.

Introduction: Three-dimensional echocardiography (3DE) has been shown to be superior to 2DE when quantifying chamber dimensions. However, the clinical utility of 3DE has been limited by time-consuming analysis and need for 3D-specific training. This study aims to assess the clinical utility of a “hands-off,” artificial intelligence-driven software program, Philips Dynamic HeartModelA.I. (DHM), in a pediatric population. Hypothesis: We hypothesize that this program will be able to accurately calculate LVEF in children when compared to Cardiac MRI (CMRI) used as a gold standard. Methods: To date, 10 patients (Average Age 14.8±1.9) have undergone CMRI immediately followed by echocardiography at the Children’s Hospital of Philadelphia. Echocardiographic images were analyzed via DHM without manual editing and from full-volume 3D border tracing (3DEF). We excluded 3D imaging of 2 patients due to poor image quality. 2D LVEF was also evaluated visually in all patients by three experts, and by 2D Simpson’s Biplane method. All analyses were timed with a stopwatch. Each technique was correlated with CMRI. Results: Our results showed that LVEF measured via DHM was rapid and correlated very well with CMRI (R=0.85). DHM had a stronger correlation with CMRI than Biplane, 3DEF, and visual EF (R=0.56; R=0.68; R=0.57). Moreover, DHM analysis was faster than both Biplane and 3DEF (32±8 seconds vs 100±19 seconds, p<0.005; 32±8 seconds vs 98±16 seconds, p<0.005) (Figure 1). Notably, 3DEF correlated very well with visual estimation by expert observers (R=0.83). Conclusions: Based on our pilot data, DHM analysis in children was faster than both 3DEF and biplane method likely due to its hands-off nature. Furthermore, its correlation with CMRI was superior to both 3DEF and Biplane. Based on further patient enrollment by us and others, this completely automated method will likely be clinically useful as it has potential to become a standard application in large volume, busy echo labs.

Introduction: Three-dimensional echocardiography (3DE) has been shown to be superior to two-dimensional echocardiography (2DE) for the quantification of chamber volumes and dimensions. However, the utility of 3DE in routine clinical practice has been restricted by time-consuming analysis and the need for 3D-specific training. This study aims to assess the accuracy and clinical utility of Philips Dynamic Heart ModelA.I. (DHM), a “hands off” automated software program, that may be used to measure LA chamber dimensions. This is notable, as indexed LA volume has been used as a predictor of heart failure in adults. Hypothesis: We hypothesize that DHM will be able to quickly and accurately calculate left atrial chamber volume when compared to Cardiac MRI (CMRI) used as a gold standard. Methods: To date, 10 patients (Average Age 14.8±1.9) have undergone clinically indicated CMRI, immediately followed by 3DE, at the Children’s Hospital of Philadelphia. 3D images were analyzed via DHM without manual editing (hands-off approach). DHM automatically calculated maximum LA volume. LA volume was also calculated from CMRI images using the biplane method. LA volume measurements by DHM were correlated with CMRI. Results: DHM was able to calculate LA volume in an average time of 32±8 seconds, without additional human input. Furthermore, inter-technique correlations showed that LA volume measurements made via DHM correlated very well with LA volume measurements made via CMRI (R=0.85, p<0.005). (Figure 1) Conclusions: In children, fully automated evaluation of LA volume based on artificial intelligence is a viable alternative to time-consuming 3D analysis when compared to a CMRI gold standard. This method of “hands-off” analysis may prove to be useful in situations where trained 3D personnel are unavailable. Furthermore, the utilization of this method may result in a greater integration of 3D LA volume into routine clinical practice.

Introduction: Children with dilated cardiomyopathy (DCM) are increasingly bridged to heart transplant (Tx) with intracorporeal continuous flow ventricular assist devices (VADs), but there continues to be variability in hospital discharge. We sought to assess the impact of a quality improvement (QI) project promoting hospital discharge in pediatric VAD patients with DCM. Methods: Patients enrolled at sites participating in the Discharge and De-Escalation QI project of the Advanced Cardiac Therapies Improving Outcomes Network (ACTION) registry were eligible. Patients with a HeartWare (HVAD) or HeartMate3 (HM3) VAD, implanted between April 2018 and February 2021, were included. Patient characteristics and outcomes were compared before and after the QI initiative, which targeted team and family expectations, was implemented in November 2019. Results: There were 85 patients (75%) with DCM and/or myocarditis who were included in this study (median age 14 years; median weight 57.1 kg; 67% male). Among 57 patients in the baseline group, 56% (n=32) were discharged with a mean post-implant hospital length of stay (LOS) of 36 days and 44% (n=25) underwent Tx during index VAD admission, with a mean of 52 days on device. There were 28 patients in the intervention group; 64% (n=18) were discharged with a mean LOS of 45 days, while 29% (n=8) patients underwent Tx during index VAD admission, with a mean of 44 hospital days on device. There was no significant difference in the frequency of hospital discharge or in hospital LOS between groups. Conclusions: Pediatric centers discharged just over half of DCM patients supported on an HVAD or HM3, with nearly one third of patients undergoing transplant during the index VAD admission. The QI intervention did not significantly alter the discharge rate. Further work is required to understand practice variation between centers with respect to Tx listing and organ acceptance for children on intracorporeal continuous flow VADs.