Pre-Operative SARS-CoV-2 Testing in Asymptomatic Heart Transplantation Recipients

INTRODUCTION

From the start of the coronavirus disease 2019 (COVID-19) pandemic, international guidelines have recommended pre-operative screening for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) before heart transplantation (HTx). Due to the changing prevalence of COVID-19, the chances of false positive results have increased. Because of increased immunity in the population and evolution of SARS-CoV-2 to current Omicron variants, associated mortality and morbidity have decreased. We set out to investigate the yield and side effects of SARS-CoV-2 screening in our center.

METHODS

We performed a retrospective cohort study in the University Medical Center Utrecht. The study period was from March 2019 to January 2023. All data from patients who underwent HTx were collected, including all pre-operative and post-operative SARS-CoV-2 tests. Furthermore, all clinical SARS-CoV-2 tests for the indication of potential HTx were screened.

RESULTS

In the period under study, 51 patients underwent HTx. None of the recipients reported any symptoms of a viral infection. Fifty HTx recipients were screened for SARS-CoV-2. Forty-nine out of fifty patients tested negative. One patient had a false positive result, potentially delaying the HTx procedure. There were no cancelled HTx procedures due to a true positive SARS-CoV-2 test result.

CONCLUSION

Pre-operative SARS-CoV-2 screening in asymptomatic HTx recipients did not lead to any true positive cases. In 2% of the cases, screening resulted in a false positive test result. With the current Omicron variants, in combination with a low-prevalence situation, we propose to abandon pre-operative SARS-CoV-2 screening and initiate a symptom-driven approach for the general viral testing of patients who are called in for a potential HTx.

Clinically Significant Incidental Findings on CT Imaging During TAVI Work-up: A Systematic Review and Meta-Analysis

BACKGROUND

The transcatheter aortic valve implantation (TAVI) population is mostly elderly and frail. Clinically significant incidental findings (SIFs) are commonly encountered in the work-up of TAVI patients. This is a systematic review of current literature on the occurrence of SIFs on computed tomography (CT) imaging preceding TAVI and their association with mortality, delayed planning, and procedure cancellation.

METHODS

A systematic search on Medline, Embase, and Cochrane resulted in 19 retrospective studies (published from 2010-2020) reporting SIFs in the work-up for TAVI. A total of 6358 individuals from 19 studies were analyzed, with mean age of 80 years and sex equally divided. A random-effects meta-analysis was performed, with weighting based on study size.

RESULTS

Pooled prevalence of patients with SIF was 22.2% (95% confidence interval [CI], 17.8-26.6) and most findings (48.3%) were found in the lungs. Pooled prevalence of new malignancies was 3.4% (95% CI, 2.5-4.4). Higher mortality in patients with SIF was only found in studies with a follow-up period >4 years (hazard ratio, 1.5-1.7). TAVI was more frequently cancelled in patients with SIF vs those with no SIF (ranges, 10.1%-47.1% vs 5.2%-37.0%, respectively). SIF did not delay time to TAVI (ranges, 6-91 days in SIF patients vs 4-81 days in non-SIF patients).

CONCLUSION

SIFs are common in patients screened for TAVI. SIF is associated with a higher risk of TAVI cancellation and with increased mortality risk over the long term, which should be taken into consideration in decision making. These findings may help inform patients and aid patient selection.

Combined meta-analysis of preclinical cell therapy studies shows overlapping effect modifiers for multiple diseases

Introduction

Cell therapy has been studied in many different research domains. Cellular replacement of damaged solid tissues is at an early stage of development, with much still to be understood. Systematic reviews and meta-analyses are widely used to aggregate data and find important patterns of results within research domains.

We set out to find common biological denominators affecting efficacy in preclinical cell therapy studies for renal, neurological and cardiac disease.

Methods

We used datasets of five previously published meta-analyses investigating cell therapy in preclinical models of chronic kidney disease, spinal cord injury, stroke and ischaemic heart disease. We transformed primary outcomes to ratios of means to permit direct comparison across disease areas. Prespecified variables of interest were species, immunosuppression, cell type, cell origin, dose, delivery and timing of the cell therapy.

Results

The five datasets from 506 publications yielded data from 13 638 animals. Animal size affects therapeutic efficacy in an inverse manner. Cell type influenced efficacy in multiple datasets differently, with no clear trend for specific cell types being superior. Immunosuppression showed a negative effect in spinal cord injury and a positive effect in cardiac ischaemic models. There was a dose–dependent relationship across the different models. Pretreatment seems to be superior compared with administration after the onset of disease.

Conclusions

Preclinical cell therapy studies are affected by multiple variables, including species, immunosuppression, dose and treatment timing. These data are important when designing preclinical studies before commencing clinical trials.

The hemodynamic effect of different left ventricular unloading techniques during veno-arterial extracorporeal life support: a systematic review and meta-analysis

Background:

Pulmonary edema and left ventricular thrombosis may arise during veno-arterial extracorporeal life support due to an increase in cardiac load. This mechanical stress can be reduced through different left ventricular unloading techniques. We set out to quantitatively summarize the hemodynamic effects of available methods in patients treated with veno-arterial extracorporeal life support.

Methods:

Literature was systematically searched for studies reporting left ventricular unloading during veno-arterial extracorporeal life support as reflected by changes in left atrial pressure, pulmonary capillary wedge pressure, diastolic pulmonary artery pressure, or left ventricular end-diastolic pressure. For studies including ⩾10 patients per group, changes in these parameters were pooled using (1) standardized mean differences and (2) ratio of means. Assessment of potential bias was performed for all studies.

Results:

Eight studies met the inclusion criteria. Reported techniques included use of intra-aortic balloon pump (n = 1), micro-axial blood pump (Impella®, n = 2), left ventricular venting (n = 1), and atrial septostomy (n = 4). Overall, left ventricular unloading was associated with a statistically significant reduction in preload parameters (standardized mean differences = −1.05 (95% confidence interval = −1.24 to −0.86) and ratio of means = 0.60 (0.47 to 0.76)). Effect sizes were strongest for micro-axial blood pump and atrial septostomy (standardized mean differences = −1.11 (−1.55 to −0.68) and −1.22 (−1.47 to −0.96), and ratio of means = 0.58 (0.39 to 0.86) and 0.54 (0.36 to 0.83), respectively).

Conclusion:

Left ventricular unloading was associated with a significant reduction in left ventricular preload parameters in the setting of veno-arterial extracorporeal life support. This effect may be most pronounced for micro-axial blood pump and atrial septostomy.

Optimization of large animal MI models; a systematic analysis of control groups from preclinical studies

Large animal models are essential for the development of novel therapeutics for myocardial infarction. To optimize translation, we need to assess the effect of experimental design on disease outcome and model experimental design to resemble the clinical course of MI. The aim of this study is therefore to systematically investigate how experimental decisions affect outcome measurements in large animal MI models. We used control animal-data from two independent meta-analyses of large animal MI models. All variables of interest were pre-defined. We performed univariable and multivariable meta-regression to analyze whether these variables influenced infarct size and ejection fraction. Our analyses incorporated 246 relevant studies. Multivariable meta-regression revealed that infarct size and cardiac function were influenced independently by choice of species, sex, co-medication, occlusion type, occluded vessel, quantification method, ischemia duration and follow-up duration. We provide strong systematic evidence that commonly used endpoints significantly depend on study design and biological variation. This makes direct comparison of different study-results difficult and calls for standardized models. Researchers should take this into account when designing large animal studies to most closely mimic the clinical course of MI and enable translational success.

Standardized mean differences cause funnel plot distortion in publication bias assessments

Meta-analyses are increasingly used for synthesis of evidence from biomedical research, and often include an assessment of publication bias based on visual or analytical detection of asymmetry in funnel plots. We studied the influence of different normalisation approaches, sample size and intervention effects on funnel plot asymmetry, using empirical datasets and illustrative simulations. We found that funnel plots of the Standardized Mean Difference (SMD) plotted against the standard error (SE) are susceptible to distortion, leading to overestimation of the existence and extent of publication bias. Distortion was more severe when the primary studies had a small sample size and when an intervention effect was present. We show that using the Normalised Mean Difference measure as effect size (when possible), or plotting the SMD against a sample size-based precision estimate, are more reliable alternatives. We conclude that funnel plots using the SMD in combination with the SE are unsuitable for publication bias assessments and can lead to false-positive results.

Targeting chronic cardiac remodeling with cardiac progenitor cells in a murine model of ischemia/reperfusion injury

BACKGROUND

Translational failure for cardiovascular disease is a substantial problem involving both high research costs and an ongoing lack of novel treatment modalities. Despite the progress already made, cell therapy for chronic heart failure in the clinical setting is still hampered by poor translation. We used a murine model of chronic ischemia/reperfusion injury to examine the effect of minimally invasive application of cardiac progenitor cells (CPC) in cardiac remodeling and to improve clinical translation.

METHODS

28 days after the induction of I/R injury, mice were randomized to receive either CPC (0.5 million) or vehicle by echo-guided intra-myocardial injection. To determine retention, CPC were localized in vivo by bioluminescence imaging (BLI) two days after injection. Cardiac function was assessed by 3D echocardiography and speckle tracking analysis to quantify left ventricular geometry and regional myocardial deformation.

RESULTS

BLI demonstrated successful injection of CPC (18/23), which were mainly located along the needle track in the anterior/septal wall. Although CPC treatment did not result in overall restoration of cardiac function, a relative preservation of the left ventricular end-diastolic volume was observed at 4 weeks follow-up compared to vehicle control (+5.3 ± 2.1 μl vs. +10.8 ± 1.5 μl). This difference was reflected in an increased strain rate (+16%) in CPC treated mice.

CONCLUSIONS

CPC transplantation can be adequately studied in chronic cardiac remodeling using this study set-up and by that provide a translatable murine model facilitating advances in research for new therapeutic approaches to ultimately improve therapy for chronic heart failure.

Abstract 55: The Natural Course of Myocardial Infarction in Large Animal Models; a Systematic Review and Meta-analysis

Background: Large animal models of myocardial infarction (MI) are essential for the development of novel therapeutic strategies. However, it is unclear which experimental factors are independent determinants of disease progression outcomes and the fidelity with which these models resemble MI in humans. The aim of this study was to investigate systematically what independently influences the outcome after MI in large animal models and determine which methodological factors influence primary endpoints and disease progression.

Methods: We used control animal data from two meta-analyses of large animal models of MI. We performed univariable and multivariable meta-regression to analyze if potential relevant variables were influencing outcomes; infarct size as a ratio of the area at risk (IS/AAR), as a ratio of the left ventricle (IS/LV) and ejection fraction (EF). Pre-defined independent variables were species, sex, weight, ischemia model (open vs closed), occlusion type (temporary vs permanent), occluded vessel, follow-up duration, use of co-medication, use of immunosuppression and study quality. Outcomes and variables were complemented per dataset if needed.

Results: Our analyses yielded 246 relevant studies, reporting 1500, 1221 and 775 control animals for IS/AAR, IS/LV and EF respectively. Multivariable meta-regression showed IS/AAR was influenced by species (p<0.001), sex (p=0.03), co-medication (p=0.01), occlusion type (p<0.001), occluded vessel (p=0.002) and follow-up (p=0.001). For IS/LV occlusion type (p=0.03), occluded vessel (p=0.03) and study quality (p=0.03) showed significant effects. EF measurements revealed that species (p=0.04), sex (p=0.04) and occluded vessel (p=0.05) were independent predictors. Using these variables, we can partially predict these outcomes for certain study setups.

Conclusion: Many methodological variations exist in the design of large animal MI studies. This should be taken into account when selecting a model to study therapy efficacy. We provide evidence that disease manifestation and progression greatly depend on certain biological characteristics, e.g. location of MI and sex of the patient. It is therefore possible that therapies have a different effect in specific patient populations.

Monocyte gene expression and coronary artery disease

PURPOSE OF REVIEW

Despite current therapy, coronary artery disease (CAD) remains the major cause of morbidity and mortality worldwide. CAD is the consequence of a complex array of deranged metabolic processes including the immune system. In this context, monocytes and macrophages are indisputable players. Thus, monocyte gene expression analysis could be a powerful tool to provide new insights in the pathophysiology of CAD and improve identification of individuals at risk. We discuss current literature assessing monocyte gene expression and its association with CAD.

RECENT FINDINGS

Monocyte surface markers CD14 ⁺⁺and CD16⁺ have been established as biomarkers for increased cardiovascular disease risk in a large number of studies. More in-depth gene expression analysis identified several interesting genes, such as ABCA1, CD36 and MSR1 with an increased expression in circulating monocytes from patients with CAD. The results for CD36 were replicated in one other study. For ABCA1 and MSR1 conflicting data are published.

SUMMARY

Recent findings indicate that genetic differences exist in circulating monocytes of patients suffering from CAD, giving us more insights into the underlying mechanisms. However, larger studies are required to prove that monocytes' expression signature could serve as a marker for diagnostic purposes in the future.