Facial appearance associates with longitudinal multi-organ failure: an ICU cohort study.

BACKGROUND: Facial appearance, whether consciously or subconsciously assessed, may affect clinical assessment and treatment strategies in the Intensive Care Unit (ICU). Nevertheless, the association between objective clinical measurement of facial appearance and multi-organ failure is currently unknown. The objective of this study was to examine whether facial appearance at admission is associated with longitudinal evaluation of multi-organ failure. METHODS: This was a sub-study of the Simple Intensive Care Studies-II, a prospective observational cohort study. All adult patients acutely admitted to the ICU between March 26, 2019, and July 10, 2019, were included. Facial appearance was assessed within three hours of ICU admission using predefined pictograms. The SOFA score was serially measured each day for the first seven days after ICU admission. The association between the extent of eye-opening and facial skin colour with longitudinal Sequential Organ Failure Assessment (SOFA) scores was investigated using generalized estimation equations. RESULTS: SOFA scores were measured in 228 patients. Facial appearance scored by the extent of eye-opening was associated with a higher SOFA score at admission and follow-up (unadjusted 0.7 points per step (95%CI 0.5 to 0.9)). There was no association between facial skin colour and a worse SOFA score over time. However, patients with half-open or closed eyes along with flushed skin had a lower SOFA score than patients with a pale or normal facial skin colour (P-interaction < 0.1). CONCLUSIONS: The scoring of patients' facial cues, primarily the extent of eye-opening and facial colour, provided valuable insights into the disease state and progression of the disease of critically ill patients. The utilization of advanced monitoring techniques that incorporate facial appearance holds promise for enhancing future intensive care support.

Deep embedded clustering generalisability and adaptation for integrating mixed datatypes: two critical care cohorts.

We validated a Deep Embedded Clustering (DEC) model and its adaptation for integrating mixed datatypes (in this study, numerical and categorical variables). Deep Embedded Clustering (DEC) is a promising technique capable of managing extensive sets of variables and non-linear relationships. Nevertheless, DEC cannot adequately handle mixed datatypes. Therefore, we adapted DEC by replacing the autoencoder with an X-shaped variational autoencoder (XVAE) and optimising hyperparameters for cluster stability. We call this model "X-DEC". We compared DEC and X-DEC by reproducing a previous study that used DEC to identify clusters in a population of intensive care patients. We assessed internal validity based on cluster stability on the development dataset. Since generalisability of clustering models has insufficiently been validated on external populations, we assessed external validity by investigating cluster generalisability onto an external validation dataset. We concluded that both DEC and X-DEC resulted in clinically recognisable and generalisable clusters, but X-DEC produced much more stable clusters.

Rotational thromboelastometry as a biomarker for mortality - The Maastricht Intensive Care COVID cohort.

BACKGROUND: Patients with severe coronavirus disease 2019 (COVID-19) present with persisting hypercoagulability, hypofibrinolysis and prolonged clot initiation as measured with viscoelastic assays. The objective of this study was to investigate the trajectories of traditional assays of hemostasis, routine and tissue plasminogen activator (tPA) rotational thromboelastometry (ROTEM) in COVID-19 patients and to study their association with mortality. METHODS: Patients enrolled within the Maastricht Intensive Care COVID (MaastrICCht) cohort were included. Traditional assays of hemostasis (prothrombin time; PT, fibrinogen and D-dimer) were measured daily and ROTEM EXTEM, FIBTEM and tPA assays were performed weekly. Trajectories of these biomarkers were analyzed over time for survivors and non-survivors using linear mixed-effects models. Additional Fine and Gray competing risk survival analysis was performed for the first available measurement after intubation. RESULTS: Of the 138 included patients, 57 (41 %) died in the intensive care unit (ICU). Over 450, 400 and 1900 individual measurements were available for analysis of routine, tPA ROTEM and traditional assays of hemostasis, respectively, with a median [IQR] follow-up of 15 [8-24] days. Non-survivors on average had prolonged CT (clotting time) and increased fibrinogen compared to survivors. MCF (maximum clot firmness), LOT (lysis onset time), LT (lysis time) and PT measurements increased more over time in non-survivors compared to survivors. Associations persisted after adjustment for demographics and disease severity. EXTEM and FIBTEM CT at intubation were associated with increased 45-day ICU mortality. CONCLUSIONS: ROTEM measurements demonstrate a further increase of hypercoagulability and (hypo)fibrinolysis parameters in non-survivors throughout ICU admission. Furthermore, prolonged CT at intubation was associated with higher 45-day ICU mortality.

Higher levels of circulating desphospho-uncarboxylated matrix Gla protein over time are associated with worse survival: the prospective Maastricht Intensive Care COVID cohort.

BACKGROUND: Extra-hepatic vitamin K-status, measured by dephosphorylated uncarboxylated matrix Gla protein (dp-ucMGP), maintains vascular health, with high levels reflecting poor vitamin K status. The occurrence of extra-hepatic vitamin K deficiency throughout the disease of COVID-19 and possible associations with pulmonary embolism (PE), and mortality in intensive care unit (ICU) patients has not been studied. The aim of this study was to investigated the association between dp-ucMGP, at endotracheal intubation (ETI) and both ICU and six months mortality. Furthermore, we studied the associations between serially measured dp-ucMGP and both PE and mortality. METHODS: We included 112 ICU patients with confirmed COVID-19. Over the course of 4 weeks after ETI, dp-ucMGP was measured serially. All patients underwent computed tomography pulmonary angiography (CTPA) to rule out PE. Results were adjusted for patient characteristics, disease severity scores, inflammation, renal function, history of coumarin use, and coronary artery calcification (CAC) scores. RESULTS: Per 100 pmol/L dp-ucMGP, at ETI, the odds ratio (OR) was 1.056 (95% CI: 0.977 to 1.141, p = 0.172) for ICU mortality and 1.059 (95% CI: 0.976 to 1.059, p = 0.170) for six months mortality. After adjustments for age, gender, and APACHE II score, the mean difference in plasma dp-ucMGP over time of ICU admission was 167 pmol/L (95% CI: 4 to 332, p = 0.047). After additional adjustments for c-reactive protein, creatinine, and history of coumarin use, the difference was 199 pmol/L (95% CI: 50 to 346, p = 0.010). After additional adjustment for CAC score the difference was 213 pmol/L (95% CI: 3 to 422, p = 0.051) higher in ICU non-survivors compared to the ICU survivors. The regression slope, indicating changes over time, did not differ. Moreover, dp-ucMGP was not associated with PE. CONCLUSION: ICU mortality in COVID-19 patients was associated with higher dp-ucMGP levels over 4 weeks, independent of age, gender, and APACHE II score, and not explained by inflammation, renal function, history of coumarin use, and CAC score. No association with PE was observed. At ETI, higher levels of dp-ucMGP were associated with higher OR for both ICU and six month mortality in crude and adjusted modes, although not statistically significantly.

Applications of rotational thromboelastometry in heparin monitoring in critical COVID-19 disease: Observations in the Maastricht Intensive Care COVID cohort.

Background: Critically ill COVID-19 patients are at risk for venous thromboembolism (VTE). Therefore, they receive thromboprophylaxis and, when appropriate, therapeutic unfractionated heparin (UFH) or low-molecular-weight heparin (LMWH). To monitor heparins in COVID-19 disease, whole-blood rotational thromboelastometry (ROTEM) may be a promising alternative to the aPTT and anti-Xa assays. Objective: To evaluate the ROTEM INTEM/HEPTEM ratios in mechanically ventilated COVID-19 patients treated with UFH and therapeutic LMWH. Material and methods: A subcohort of mechanically ventilated COVID-19 patients of the prospective Maastricht Intensive Care Covid (MaastrICCht) cohort was studied. Anti-Xa, aPTT, and ROTEM measurements following treatment with UFH or therapeutic dose of LMWH (nadroparin) were evaluated using uni- and multivariable linear regression analysis and receiver operating characteristics. Results: A total of 98 patients were included, of which 82 were treated with UFH and 16 with therapeutic LMWH. ROTEM-measured INTEM/HEPTEM CT ratio was higher in patients using UFH (1.4 [1.3-1.4]) compared to patients treated with LMWH (1.0 [1.0-1.1], p < 0.001). Both the aPTT and anti-Xa were associated with the CT ratio. However, the ß-regression coefficient (95%CI) was significantly higher in patients on UFH (0.31 (0.001-0.62)) compared to therapeutic LMWH (0.09 (0.05-0.13)) for comparison with the anti-Xa assay. Furthermore, ROC analysis demonstrated an area under the curve for detecting UFH of 0.936(0.849-1.00), 0.851(0.702-1.000), and 0.645(0.465-0.826) for the CT ratio, aPTT, and anti-Xa, respectively. Conclusion: The ROTEM INTEM/HEPTEM CT ratio appears a promising tool to guide anticoagulant therapy in ICU patients with COVID-19 disease, but associations with clinical endpoints are currently lacking.

Serial thrombin generation and exploration of alternative anticoagulants in critically ill COVID-19 patients: Observations from Maastricht Intensive Care COVID Cohort.

Background: COVID-19 associated coagulopathy (CAC) is associated with an increase in thromboembolic events. Current guidelines recommend prophylactic heparins in the management of CAC. However, the efficacy of this strategy in the intensive care population remains uncertain. Objective: We aimed to measure thrombin generation (TG) to assess CAC in intensive care unit (ICU) patients receiving thromboprophylaxis with low molecular weight heparin (LMWH) or unfractionated heparin (UFH). In addition, we performed statistical modeling to link TG parameters to patient characteristics and clinical parameters. Lastly, we studied the potency of different anticoagulants as an alternative to LMWH treatment in ex vivo COVID-19 plasma. Patients/Methods: We included 33 patients with confirmed COVID-19 admitted at the ICU. TG was measured at least twice over the course of 6 weeks after admission. Thrombin generation parameters peak height and endogenous thrombin potential (ETP) were compared to healthy controls. Results were subsequently correlated with a patient characteristics and laboratory measurements. In vitro spiking in TG with rivaroxaban, dabigatran, argatroban and orgaran was performed and compared to LMWH. Results: Anti-Xa levels of all patients remained within the therapeutic range throughout follow-up. At baseline, the mean (SE) endogenous thrombin potential (ETP) was 1,727 (170) nM min and 1,620 (460) nM min for ellagic acid (EA) and tissue factor (TF), respectively. In line with this we found a mean (SE) peak height of 353 (45) nM and 264 (96) nM for EA and TF. Although fluctuating across the weeks of follow-up, TG parameters remained elevated despite thromboprophylaxis. In vitro comparison of LMWHs and direct thrombin inhibitors (e.g., agratroban, dabigatran) revealed a higher efficacy in reducing coagulation potential for direct thrombin inhibition in both ellagic acid (EA) and tissue factor (TF) triggered TG. Conclusion: In a sub-group of mechanically ventilated, critically ill COVID-19 patients, despite apparent adequate anti-coagulation doses evaluated by anti-Xa levels, thrombin generation potential remained high during ICU admission independent of age, sex, body mass index, APACHE II score, cardiovascular disease, and smoking status. These observations could, only partially, be explained by (anti)coagulation and thrombosis, inflammation, and multi-organ failure. Our in vitro data suggested that direct thrombin inhibition compared with LMWH might offer an alternate, more effective anticoagulant strategy in COVID-19.

Serial Assessment of Myocardial Injury Markers in Mechanically Ventilated Patients With SARS-CoV-2 (from the Prospective MaastrICCht Cohort).

Myocardial injury in COVID-19 is associated with in-hospital mortality. However, the development of myocardial injury over time and whether myocardial injury in patients with COVID-19 at the intensive care unit is associated with outcome is unclear. This study prospectively investigates myocardial injury with serial measurements over the full course of intensive care unit admission in mechanically ventilated patients with COVID-19. As part of the prospective Maastricht Intensive Care COVID cohort, predefined myocardial injury markers, including high-sensitivity cardiac troponin T (hs-cTnT), N-terminal pro-B-type natriuretic peptide (NT-proBNP), and electrocardiographic characteristics were serially collected in mechanically ventilated patients with COVID-19. Linear mixed-effects regression was used to compare survivors with nonsurvivors, adjusting for gender, age, APACHE-II score, daily creatinine concentration, hypertension, diabetes mellitus, and obesity. In 90 patients, 57 (63%) were survivors and 33 (37%) nonsurvivors, and a total of 628 serial electrocardiograms, 1,565 hs-cTnT, and 1,559 NT-proBNP concentrations were assessed. Log-hs-cTnT was lower in survivors compared with nonsurvivors at day 1 (ß -0.93 [-1.37; -0.49], p <0.001) and did not change over time. Log-NT-proBNP did not differ at day 1 between both groups but decreased over time in the survivor group (ß -0.08 [-0.11; -0.04] p <0.001) compared with nonsurvivors. Many electrocardiographic abnormalities were present in the whole population, without significant differences between both groups. In conclusion, baseline hs-cTnT and change in NT-proBNP were strongly associated with mortality. Two-thirds of patients with COVID-19 showed electrocardiographic abnormalities. Our serial assessment suggests that myocardial injury is common in mechanically ventilated patients with COVID-19 and is associated with outcome.

Hemostasis and fibrinolysis in COVID-19 survivors 6 months after intensive care unit discharge.

BACKGROUND: The prothrombotic phenotype has been extensively described in patients with acute coronavirus disease 2019 (COVID-19). However, potential long-term hemostatic abnormalities are unknown. OBJECTIVE: To evaluate the changes in routine hemostasis laboratory parameters and tissue-type plasminogen activator (tPA) rotational thromboelastometry (ROTEM) 6 months after COVID-19 intensive care unit (ICU) discharge in patients with and without venous thromboembolism (VTE) during admission. METHODS: Patients with COVID-19 of the Maastricht Intensive Care COVID cohort with tPA ROTEM measurement at ICU and 6-month follow-up were included. TPA ROTEM is a whole blood viscoelastic assay that illustrates both clot development and fibrinolysis due to simultaneous addition of tissue factor and tPA. Analyzed ROTEM parameters include clotting time, maximum clot firmness (MCF), lysis onset time (LOT), and lysis time (LT). RESULTS: Twenty-two patients with COVID-19 were included and showed extensive hemostatic abnormalities before ICU discharge. TPA ROTEM MCF (75 mm [interquartile range, 68-78]-59 mm [49-63]; P ≤ .001), LOT (3690 seconds [2963-4418]-1786 seconds [1465-2650]; P ≤ .001), and LT (7200 seconds [6144-7200]-3138 seconds [2591-4389]; P ≤ .001) normalized 6 months after ICU discharge. Of note, eight and four patients still had elevated fibrinogen and D-dimer concentrations at follow-up, respectively. In general, no difference in median hemostasis parameters at 6-month follow-up was observed between patients with (n=14) and without (n=8) VTE, although fibrinogen appeared to be lower in the VTE group (VTE-, 4.3 g/L [3.7-4.7] vs VTE+, 3.4 g/L [3.2-4.2]; P = .05). CONCLUSIONS: Six months after COVID-19 ICU discharge, no persisting hypercoagulable or hypofibrinolytic profile was detected by tPA ROTEM. Nevertheless, increased D-dimer and fibrinogen concentrations persist up to 6 months in some patients, warranting further exploration of the role of hemostasis in long-term morbidity after hospital discharge.

Serial markers of coagulation and inflammation and the occurrence of clinical pulmonary thromboembolism in mechanically ventilated patients with SARS-CoV-2 infection; the prospective Maastricht intensive care COVID cohort.

BACKGROUND: The incidence of pulmonary thromboembolism is high in SARS-CoV-2 patients admitted to the Intensive Care. Elevated biomarkers of coagulation (fibrinogen and D-dimer) and inflammation (c-reactive protein (CRP) and ferritin) are associated with poor outcome in SARS-CoV-2. Whether the time-course of fibrinogen, D-dimer, CRP and ferritin is associated with the occurrence of pulmonary thromboembolism in SARS-CoV-2 patients is unknown. We hypothesise that patients on mechanical ventilation with SARS-CoV-2 infection and clinical pulmonary thromboembolism have lower concentrations of fibrinogen and higher D-dimer, CRP, and ferritin concentrations over time compared to patients without a clinical pulmonary thromboembolism. METHODS: In a prospective study, fibrinogen, D-dimer, CRP and ferritin were measured daily. Clinical suspected pulmonary thromboembolism was either confirmed or excluded based on computed tomography pulmonary angiography (CTPA) or by transthoracic ultrasound (TTU) (i.e., right-sided cardiac thrombus). In addition, patients who received therapy with recombinant tissue plasminogen activator were included when clinical instability in suspected pulmonary thromboembolism did not allow CTPA. Serial data were analysed using a mixed-effects linear regression model, and models were adjusted for known risk factors (age, sex, APACHE-II score, body mass index), biomarkers of coagulation and inflammation, and anticoagulants. RESULTS: Thirty-one patients were considered to suffer from pulmonary thromboembolism ((positive CTPA (n = 27), TTU positive (n = 1), therapy with recombinant tissue plasminogen activator (n = 3)), and eight patients with negative CTPA were included. After adjustment for known risk factors and anticoagulants, patients with, compared to those without, clinical pulmonary thromboembolism had lower average fibrinogen concentration of - 0.9 g/L (95% CI: - 1.6 - - 0.1) and lower average ferritin concentration of - 1045 µg/L (95% CI: - 1983 - - 106) over time. D-dimer and CRP average concentration did not significantly differ, 561 µg/L (- 6212-7334) and 27 mg/L (- 32-86) respectively. Ferritin lost statistical significance, both in sensitivity analysis and after adjustment for fibrinogen and D-dimer. CONCLUSION: Lower average concentrations of fibrinogen over time were associated with the presence of clinical pulmonary thromboembolism in patients at the Intensive Care, whereas D-dimer, CRP and ferritin were not. Lower concentrations over time may indicate the consumption of fibrinogen related to thrombus formation in the pulmonary vessels.

Serial EXTEM, FIBTEM, and tPA Rotational Thromboelastometry Observations in the Maastricht Intensive Care COVID Cohort-Persistence of Hypercoagulability and Hypofibrinolysis Despite Anticoagulation.

Background: Coronavirus Disease 2019 (COVID-19) patients often present with thromboembolic events. In COVID-19 patients, routine hemostatic assays cannot correctly identify patients at risk for thromboembolic events. Viscoelastic testing with rotational thromboelastometry (ROTEM) might improve the characterization of COVID-19-associated coagulopathy. Objective: To unravel underlying coagulopathy and fibrinolysis over time as measured by serial assessment heparin-independent (FIBTEM and EXTEM) and fibrinolysis illustrating (tissue plasminogen activator; tPA) ROTEM assays. Patients/Methods: Between April 23 and June 12, consecutive adult patients enrolled within the Maastricht Intensive Care COVID (MaastrICCht) cohort were included, and a comprehensive set of clinical, physiological, pharmaceutical, and laboratory variables were collected daily. Twice per week, EXTEM, FIBTEM, and tPA ROTEM were performed. Clotting time (CT), clot formation time (CFT), maximum clot firmness (MCF), lysis onset time (LOT), and lysis time (LT) were determined to assess clot development and breakdown and were compared to routine hemostatic assays. Results: In 36 patients, 96 EXTEM/FIBTEM and 87 tPA ROTEM tests were performed during a 6-week follow-up. CT prolongation was present in 54% of EXTEM measurements, which were not matched by prothrombin time (PT) in 37%. Respectively, 81 and 99% of all EXTEM and FIBTEM MCF values were above the reference range, and median MCF remained elevated during follow-up. The ROTEM fibrinolysis parameters remained prolonged with median LOT consequently >49 min and unmeasurable LT in 56% of measurements, suggesting a severe hypofibrinolytic phenotype. Conclusion: ROTEM tests in COVID-19 ICU patients show hypercoagulability and severe hypofibrinolysis persisting over at least 6 weeks.

The "sex gap" in COVID-19 trials: a scoping review.

BACKGROUND: Many studies investigate the role of pharmacological treatments on disease course in Corona Virus Disease 2019 (COVID-19). Sex disparities in genetics, immunological responses, and hormonal mechanisms may underlie the substantially higher fatality rates reported in male COVID-19 patients. To optimise care for COVID-19 patients, prophylactic and therapeutic studies should include sex-specific design and analyses. Therefore, in this scoping review, we investigated whether studies on pharmacological treatment in COVID-19 were performed based on a priori sex-specific design or post-hoc sex-specific analyses. METHODS: We systematically searched PubMed, EMBASE, UpToDate, clinical trial.org, and MedRxiv for studies on pharmacological treatment for COVID-19 until June 6th, 2020. We included case series, randomized controlled trials, and observational studies in humans (≥18 years) investigating antiviral, antimalarial, and immune system modulating drugs. Data were collected on 1) the proportion of included females, 2) whether sex stratification was performed (a priori by design or post-hoc), and 3) whether effect modification by sex was investigated. FINDINGS: 30 studies were eligible for inclusion, investigating remdesivir (n = 2), lopinavir/ritonavir (n = 5), favipiravir (n = 1), umifenovir (n = 1), hydroxychloroquine/chloroquine (n = 8), convalescent plasma (n = 6), interleukin-6 (IL-6) pathway inhibitors (n = 5), interleukin-1 (IL-1) pathway inhibitors (n = 1) and corticosteroids (n = 3). Only one study stratified its data based on sex in a post-hoc analysis, whereas none did a priori by design. None of the studies investigated effect modification by sex. A quarter of the studies included twice as many males as females. INTERPRETATION: Analyses assessing potential interference of sex with (side-)effects of pharmacological therapy for COVID-19 are rarely reported. Considering sex differences in case-fatality rates and genetic, immunological, and hormonal mechanisms, studies should include sex-specific analyses in their design to optimise COVID-19 care. FUNDING: None.

Monitoring of Unfractionated Heparin in Severe COVID-19: An Observational Study of Patients on CRRT and ECMO.

Objective Severe cases of coronavirus disease 2019 (COVID-19) can require continuous renal replacement therapy (CRRT) and/or extracorporeal membrane oxygenation (ECMO). Unfractionated heparin (UFH) to prevent circuit clotting is mandatory but monitoring is complicated by (pseudo)-heparin resistance. In this observational study, we compared two different activated partial thromboplastin time (aPTT) assays and a chromogenic anti-Xa assay in COVID-19 patients on CRRT or ECMO in relation to their UFH dosages and acute phase reactants. Materials and Methods The aPTT (optical [aPTT-CS] and/or mechanical [aPTT-STA] clot detection methods were used), anti-Xa, factor VIII (FVIII), antithrombin III (ATIII), and fibrinogen were measured in 342 samples from 7 COVID-19 patients on CRRT or ECMO during their UFH treatment. Dosage of UFH was primarily based on the aPTT-CS with a heparin therapeutic range (HTR) of 50-80s. Associations between different variables were made using linear regression and Bland-Altman analysis. Results Dosage of UFH was above 35,000IU/24 hours in all patients. aPTT-CS and aPTT-STA were predominantly within the HTR. Anti-Xa was predominantly above the HTR (0.3-0.7 IU/mL) and ATIII concentration was >70% for all patients; mean FVIII and fibrinogen were 606% and 7.5 g/L, respectively. aPTT-CS correlated with aPTT-STA ( r 2 = 0.68) with a bias of 39.3%. Correlation between aPTT and anti-Xa was better for aPTT-CS (0.78 ≤ r 2 ≤ 0.94) than for aPTT-STA (0.34 ≤ r 2 ≤ 0.81). There was no general correlation between the aPTT-CS and ATIII, FVIII, fibrinogen, thrombocytes, C-reactive protein, or ferritin. Conclusion All included COVID-19 patients on CRRT or ECMO conformed to the definition of heparin resistance. A patient-specific association was found between aPTT and anti-Xa. This association could not be explained by FVIII or fibrinogen.

Serial measurements in COVID-19-induced acute respiratory disease to unravel heterogeneity of the disease course: design of the Maastricht Intensive Care COVID cohort (MaastrICCht).

INTRODUCTION: The course of the disease in SARS-CoV-2 infection in mechanically ventilated patients is unknown. To unravel the clinical heterogeneity of the SARS-CoV-2 infection in these patients, we designed the prospective observational Maastricht Intensive Care COVID cohort (MaastrICCht). We incorporated serial measurements that harbour aetiological, diagnostic and predictive information. The study aims to investigate the heterogeneity of the natural course of critically ill patients with a SARS-CoV-2 infection. METHODS AND ANALYSIS: Mechanically ventilated patients admitted to the intensive care with a SARS-CoV-2 infection will be included. We will collect clinical variables, vital parameters, laboratory variables, mechanical ventilator settings, chest electrical impedance tomography, ECGs, echocardiography as well as other imaging modalities to assess heterogeneity of the course of a SARS-CoV-2 infection in critically ill patients. The MaastrICCht is also designed to foster various other studies and registries and intends to create an open-source database for investigators. Therefore, a major part of the data collection is aligned with an existing national intensive care data registry and two international COVID-19 data collection initiatives. Additionally, we create a flexible design, so that additional measures can be added during the ongoing study based on new knowledge obtained from the rapidly growing body of evidence. The spread of the COVID-19 pandemic requires the swift implementation of observational research to unravel heterogeneity of the natural course of the disease of SARS-CoV-2 infection in mechanically ventilated patients. Our study design is expected to enhance aetiological, diagnostic and prognostic understanding of the disease. This paper describes the design of the MaastrICCht. ETHICS AND DISSEMINATION: Ethical approval has been obtained from the medical ethics committee (Medisch Ethische Toetsingscommissie 2020-1565/3 00 523) of the Maastricht University Medical Centre+ (Maastricht UMC+), which will be performed based on the Declaration of Helsinki. During the pandemic, the board of directors of Maastricht UMC+ adopted a policy to inform patients and ask their consent to use the collected data and to store serum samples for COVID-19 research purposes. All study documentation will be stored securely for fifteen years after recruitment of the last patient. The results will be published in peer-reviewed academic journals, with a preference for open access journals, while particularly considering deposition of the manuscripts on a preprint server early. TRIAL REGISTRATION NUMBER: The Netherlands Trial Register (NL8613).

Variability of Microcirculatory Measurements in Critically Ill Patients.

INTRODUCTION: Monitoring the microcirculation may be helpful in guiding resuscitation in patients with circulatory shock. Sublingual side-stream dark field imaging cameras allow for noninvasive, bedside evaluation of the microcirculation, although their use in clinical practice has not yet been validated. The GlycoCheck system automatically analyzes images to determine glycocalyx thickness, red blood cell filling percentage, and vessel density. Although GlycoCheck has been used to study microcirculation in critically ill patients, little is known about the reproducibility of measurements in this population. MATERIALS AND METHODS: A total of 60 critically ill patients were studied. Three consecutive microcirculation measurements were performed with the GlycoCheck system in 40 of these patients by one of two experienced observers. Twenty patients were assessed by both observers. Intra- and interobserver variability were assessed using intraclass correlation coefficients (ICCs). RESULTS: ICCs of single measurements were poor for glycocalyx thickness and good for filling percentage and vessel density. Reproducibility could be substantially increased for all parameters when three consecutive measurements were performed and averaged. DISCUSSION: GlycoCheck can be used to study microcirculation. However, to obtain reliable results three consecutive measurements should be performed and averaged. The variation of the measurements currently hampers the clinical application in individual patients.

Hypertrophic remodelling in cardiac regulatory myosin light chain (MYL2) founder mutation carriers.

AIMS: Phenotypic heterogeneity and incomplete penetrance are common in patients with hypertrophic cardiomyopathy (HCM). We aim to improve the understanding in genotype-phenotype correlations in HCM, particularly the contribution of an MYL2 founder mutation and risk factors to left ventricular hypertrophic remodelling. METHODS AND RESULTS: We analysed 14 HCM families of whom 38 family members share the MYL2 c.64G > A [p.(Glu22Lys)] mutation and a common founder haplotype. In this unique cohort, we investigated factors influencing phenotypic outcome in addition to the primary mutation. The mutation alone showed benign disease manifestation with low penetrance. The co-presence of additional risk factors for hypertrophy such as hypertension, obesity, or other sarcomeric gene mutation increased disease penetrance substantially and caused HCM in 89% of MYL2 mutation carriers (P = 0.0005). The most prominent risk factor was hypertension, observed in 71% of mutation carriers with HCM and an additional risk factor. CONCLUSION: The MYL2 mutation c.64G > A on its own is incapable of triggering clinical HCM in most carriers. However, the presence of an additional risk factor for hypertrophy, particularly hypertension, adds to the development of HCM. Early diagnosis of risk factors is important for early treatment of MYL2 mutation carriers and close monitoring should be guaranteed in this case. Our findings also suggest that the presence of hypertension or another risk factor for hypertrophy should not be an exclusion criterion for genetic studies.

Toll-Like Receptor induced CD11b and L-selectin response in patients with coronary artery disease.

Toll-Like Receptor (TLR) -2 and -4 expression and TLR-induced cytokine response of inflammatory cells are related to atherogenesis and atherosclerotic plaque progression. We examined whether immediate TLR induced changes in CD11b and L-selectin (CD62L) expression are able to discriminate the presence and severity of atherosclerotic disease by exploring single dose whole blood TLR stimulation and detailed dose-response curves. Blood samples were obtained from 125 coronary artery disease (CAD) patients and 28 controls. CD11b and L-selectin expression on CD14+ monocytes was measured after whole blood stimulation with multiple concentrations of the TLR4 ligand LPS (0.01-10 ng/ml) and the TLR2 ligand P3C (0.5-500 ng/ml). Subsequently, dose-response curves were created and the following parameters were calculated: hillslope, EC50, area under the curve (AUC) and delta. These parameters provide information about the maximum response following activation, as well as the minimum trigger required to induce activation and the intensity of the response. CAD patients showed a significantly higher L-selectin, but not CD11b response to TLR ligation than controls after single dose stimulations as well as significant differences in the hillslope and EC50 of the dose-response curves. Within the CAD patient group, dose-response curves of L-selectin showed significant differences in the presence of hypertension, dyslipidemia, coronary occlusion and degree of stenosis, whereas CD11b expression had the strongest discriminating power after single dose stimulation. In conclusion, single dose stimulations and dose-response curves of CD11b and L-selectin expression after TLR stimulation provide diverse but limited information about atherosclerotic disease severity in stable angina patients. However, both single dose stimulation and dose-response curves of LPS-induced L-selectin expression can discriminate between controls and CAD patients.

The relationship between fractional flow reserve, platelet reactivity and platelet leukocyte complexes in stable coronary artery disease.

BACKGROUND: The presence of stenoses that significantly impair blood flow and cause myocardial ischemia negatively affects prognosis of patients with stable coronary artery disease. Altered platelet reactivity has been associated with impaired prognosis of stable coronary artery disease. Platelets are activated and form complexes with leukocytes in response to microshear gradients caused by friction forces on the arterial wall or flow separation. We hypothesized that the presence of significantly flow-limiting stenoses is associated with altered platelet reactivity and formation of platelet-leukocyte complexes. METHODS: One hundred patients with stable angina were studied. Hemodynamic significance of all coronary stenoses was assessed with Fractional Flow Reserve (FFR). Patients were classified FFR-positive (at least one lesion with FFR≤0.75) or FFR-negative (all lesions FFR>0.80). Whole blood samples were stimulated with increasing concentrations of ADP, TRAP, CRP and Iloprost with substimulatory ADP. Expression of P-selectin as platelet activation marker and platelet-leukocyte complexes were measured by flowcytometry. Patients were stratified on clopidogrel use. FFR positive and negative patient groups were compared on platelet reactivity and platelet-leukocyte complexes. RESULTS: Platelet reactivity between FFR-positive patients and FFR-negative patients did not differ. A significantly lower percentage of circulating platelet-neutrophil complexes in FFR-positive patients and a similar non-significant decrease in percentage of circulating platelet-monocyte complexes in FFR-positive patients was observed. CONCLUSION: The presence of hemodynamically significant coronary stenoses does not alter platelet reactivity but is associated with reduced platelet-neutrophil complexes in peripheral blood of patients with stable coronary artery disease.

Fractional flow reserve is not associated with inflammatory markers in patients with stable coronary artery disease.

BACKGROUND: Atherosclerosis is an inflammatory condition and increased blood levels of inflammatory biomarkers have been observed in acute coronary syndromes. In addition, high expression of inflammatory markers is associated with worse prognosis of coronary artery disease. The presence and extent of inducible ischemia in patients with stable angina has previously been shown to have strong prognostic value. We hypothesized that evidence of inducible myocardial ischemia by local lesions, as measured by fractional flow reserve (FFR), is associated with increased levels of blood based inflammatory biomarkers. METHODS: Whole blood samples of 89 patients with stable angina pectoris and 16 healthy controls were analyzed. The patients with stable angina pectoris underwent coronary angiography and FFR of all coronary lesions. We analyzed plasma levels of cytokines IL-6, IL-8 and TNF-α and membrane expression of Toll-like receptor 2 and 4, CD11b, CD62L and CD14 on monocytes and granulocytes as markers of inflammation. Furthermore, we quantified the severity of hemodynamically significant coronary artery disease by calculating Functional Syntax Score (FSS), an extension of the Syntax Score. RESULTS: For the majority of biomarkers, we observed lower levels in the healthy control group compared with patients with stable angina who underwent coronary catheterization. We found no difference for any of the selected biomarkers between patients with a positive FFR (≤ 0.75) and negative FFR (>0.80). We observed no relationship between the investigated biomarkers and FSS. CONCLUSION: The presence of local atherosclerotic lesions that result in inducible myocardial ischemia as measured by FFR in patients with stable coronary artery disease is not associated with increased plasma levels of IL-6, IL-8 and TNF-α or increased expression of TLR2 and TLR4, CD11b, CD62L and CD14 on circulating leukocytes.

Functional measurement of coronary stenosis.

Fractional flow reserve (FFR) is considered nowadays as the gold standard for invasive assessment of physiologic stenosis significance and an indispensable tool for decision making in coronary revascularization. Use of FFR in the catheterization laboratory accurately identifies which lesions should be stented and improves the outcome in most elective clinical and angiographic conditions. Recently, FFR has been upgraded to a class IA classification in multivessel percutaneous coronary intervention in the guidelines on coronary revascularization of the European Society of Cardiology. In this state-of-the-art paper, the basic concept of FFR and its application, characteristics, and use in several subsets of patients are discussed from a practical point of view.

Fractional flow reserve in unstable angina and non-ST-segment elevation myocardial infarction experience from the FAME (Fractional flow reserve versus Angiography for Multivessel Evaluation) study.

OBJECTIVES: The aim of this study was to study whether there is a difference in benefit of fractional flow reserve (FFR) guidance for percutaneous coronary intervention (PCI) in multivessel coronary disease in patients with unstable angina (UA) or non-ST-segment elevation myocardial infarction (NSTEMI), compared with stable angina (SA). BACKGROUND: The use of FFR to guide PCI has been well established for patients with SA. Its use in patients with UA or NSTEMI has not been investigated prospectively. METHODS: In the FAME (Fractional flow reserve versus Angiography for Multivessel Evaluation) study 1,005 patients with multivessel disease amenable to PCI were included and randomized to either angiography-guided PCI of all lesions ≥50% or FFR-guided PCI of lesions with an FFR ≤0.80. Patients admitted for UA or NSTEMI with positive troponin but total creatine kinase <1,000 U/l were eligible for inclusion. We determined 2-year major adverse cardiac event rates of these patients and compared it with stable patients. RESULTS: Of 1,005 patients, 328 had UA or NSTEMI. There was no evidence for heterogeneity among the subgroups for any of the outcome variables (all p values >0.05). Using FFR to guide PCI resulted in similar risk reductions of major adverse cardiac events and its components in patients with UA or NSTEMI, compared with patients with SA (absolute risk reduction of 5.1% vs. 3.7%, respectively, p = 0.92). In patients with UA or NSTEMI, the number of stents was reduced without increase in hospital stay or procedure time and with less contrast use, in similarity to stable patients. CONCLUSIONS: The benefit of using FFR to guide PCI in multivessel disease does not differ between patients with UA or NSTEMI, compared with patients with SA.