Impact of very low dose rivaroxaban in addition to dual antiplatelet therapy on endogenous fibrinolysis in acute coronary syndrome: The VaLiDate-R study

BACKGROUND

Impaired endogenous fibrinolysis is adverse cardiovascular risk factor in acute coronary syndrome (ACS) patients. Addition of very low dose rivaroxaban (VLDR) to dual antiplatelet therapy (DAPT) reduces cardiovascular events but increases bleeding.

OBJECTIVE

We aimed to assess whether addition of VLDR to DAPT can enhance endogenous fibrinolysis.

METHODS

In a prospective, open-label trial, we assessed endogenous fibrinolysis in whole blood, in 549 patients with ACS using the Global Thrombosis Test (GTT) and Thromboelastography (TEG). Patients (n = 180) who demonstrated impaired endogenous fibrinolysis (lysis time [LT] >2000s with the GTT) were randomised 1:1:1 to (i) clopidogrel 75 mg daily; (ii) clopidogrel 75 mg daily plus rivaroxaban 2.5 mg twice daily; or (iii) ticagrelor 90 mg twice daily, for 30 days, in addition to aspirin. Fibrinolytic status was assessed at 0, 2, 4 and 8 weeks. The primary outcome was the change in LT from admission to week 4. We also measured thrombotic occlusion time (OT) at high shear, and rivaroxaban level.

RESULTS

There was no difference between the groups with respect to LT or clot lysis with TEG, and no change in these parameters compared to baseline during study drug allocation. In the rivaroxaban plus clopidogrel group, OT was prolonged compared to the other groups, although rivaroxaban levels were low, suggesting non-compliance.

CONCLUSION

Addition of rivaroxaban 2.5 mg twice daily to DAPT does not affect endogenous fibrinolysis of thrombus formed at either high or low shear. Further studies are needed to determine whether higher doses of rivaroxaban can favourably modulate fibrinolysis.

CONDENSED ABSTRACT

Impaired endogenous fibrinolysis is a strong risk factor in ACS. We aimed to assess whether adding very low dose rivaroxaban (VLDR) to DAPT can enhance fibrinolysis. Fibrin and clot lysis were assessed in whole blood. ACS patients with impaired fibrinolysis were randomised 1:1:1 to clopidogrel 75 mg daily; clopidogrel 75 mg plus VLDR; or ticagrelor 90 mg twice daily, in addition to aspirin. At 30-days, there was no difference in lysis time between the groups, nor change from baseline. VLDR does not improve fibrinolysis at high or low shear. Further studies are needed to determine whether alternative antithrombotic regimens can enhance endogenous fibrinolysis.

Adult Highlights From the Extracorporeal Life Support Organization Registry: 2017-2022

The Extracorporeal Life Support Organization (ELSO) registry captures clinical data and outcomes on patients receiving extracorporeal membrane oxygenation (ECMO) support across the globe at participating centers. It provides a very unique opportunity to benchmark outcomes and analyze the clinical course to help identify ways of improving patient outcomes. In this review, we summarize select adult ECMO articles published using the ELSO registry over the past 5 years. These articles highlight innovative utilization of the registry data in generating hypotheses for future clinical trials. Members of the ELSO Scientific Oversight Committee can be found here: https://www.elso.org/registry/socmembers.aspx .

Mechanisms regulating heterogeneity of hemostatic gene expression in endothelial cells

The hemostatic system involves an array of circulating coagulation factors that work in concert with platelets and the vascular endothelium to promote clotting in a space- and time-defined manner. Despite equal systemic exposure to circulating factors, bleeding and thrombotic diseases tend to prefer specific sites, suggesting an important role for local factors. This may be provided by endothelial heterogeneity. Endothelial cells differ not only between arteries, veins, and capillaries but also between microvascular beds from different organs, which present unique organotypic morphology and functional and molecular profiles. Accordingly, regulators of hemostasis are not uniformly distributed in the vasculature. The establishment and maintenance of endothelial diversity are orchestrated at the transcriptional level. Recent transcriptomic and epigenomic studies have provided a global picture of endothelial cell heterogeneity. In this review, we discuss the organotypic differences in the hemostatic profile of endothelial cells; we focus on 2 major endothelial regulators of hemostasis, namely von Willebrand factor and thrombomodulin, to provide examples of transcriptional mechanisms that control heterogeneity; finally, we consider some of the methodological challenges and opportunities for future studies.

Bleeding and thrombotic complications and their impact on mortality in patients supported with left ventricular assist device for cardiogenic shock

INTRODUCTION

Thrombosis and bleeding are major complications in patients supported with left ventricular assist devices (LVADs). We aimed to assess the incidence of bleeding and thrombosis in patients supported with a HeartWare left ventricular assist device (HVAD), their predictive factors and their impact on mortality.

METHODS

A single centre retrospective observational study of patients supported with HVAD over 5 years from January 2015 to October 2020.

RESULTS

A total 139 patients (median age 52.5, 72.1% male) were included for analysis. The probability of 1-year survival was 73.1%. Advanced age (>60 years) and EuroSCORE II score (>20%) were independently associated with reduced survival. Major bleeding and thrombosis occurred in 46.8% and 35.3% respectively. Secondary mechanical circulatory support (MCS) increased likelihood of experiencing major bleeding (HR: 2.76, 95%1.65-4.62, p < 0.0001) whilst patients receiving aspirin were protected from bleeding and thrombosis (HR: 0.34 95% CI 0.19-0.58, p < 0.001). Pre-operative anaemia (HR: 3.02, 95% CI: 1.6-5.7, p = 0.014) and use of a secondary MCS device (HR: 2.78, 95% CI: 1.2-6.3, p = 0.001) were associated with an increased risk of thrombosis. Patients with any major bleeding (with or without thrombosis) had a 7.68-fold (95% CI 3.5-16.8) increased risk of death compared to those without. In contrast, 'thrombosis only' patients had 4.23-fold (95% CI 1.8-10.2) increased risk of death compared to those without thrombosis. The risk of mortality was increased in patients with any thrombosis and the risk of death was highest in patients with major bleeding and thrombosis (HR: 16.49 [95% CI 7.7-35.3]).

CONCLUSIONS

Major bleeding and thrombosis significantly increase the 1-year mortality. Optimal perioperative haemostasis and anticoagulation remains crucial in patients supported with HVAD.

The immunology of long COVID

Long COVID is the patient-coined term for the disease entity whereby persistent symptoms ensue in a significant proportion of those who have had COVID-19, whether asymptomatic, mild or severe. Estimated numbers vary but the assumption is that, of all those who had COVID-19 globally, at least 10% have long COVID. The disease burden spans from mild symptoms to profound disability, the scale making this a huge, new health-care challenge. Long COVID will likely be stratified into several more or less discrete entities with potentially distinct pathogenic pathways. The evolving symptom list is extensive, multi-organ, multisystem and relapsing-remitting, including fatigue, breathlessness, neurocognitive effects and dysautonomia. A range of radiological abnormalities in the olfactory bulb, brain, heart, lung and other sites have been observed in individuals with long COVID. Some body sites indicate the presence of microclots; these and other blood markers of hypercoagulation implicate a likely role of endothelial activation and clotting abnormalities. Diverse auto-antibody (AAB) specificities have been found, as yet without a clear consensus or correlation with symptom clusters. There is support for a role of persistent SARS-CoV-2 reservoirs and/or an effect of Epstein-Barr virus reactivation, and evidence from immune subset changes for broad immune perturbation. Thus, the current picture is one of convergence towards a map of an immunopathogenic aetiology of long COVID, though as yet with insufficient data for a mechanistic synthesis or to fully inform therapeutic pathways.

Thombosis, major bleeding, and survival in COVID-19 supported by veno-venous extracorporeal membrane oxygenation in the first vs second wave: a multicenter observational study in the United Kingdom

BACKGROUND

Bleeding and thrombosis are major complications of veno-venous (VV) extracorporeal membrane oxygenation (ECMO).

OBJECTIVES

To assess thrombosis, major bleeding (MB), and 180-day survival in patients supported by VV-ECMO between the first (March 1 to May 31, 2020) and second (June 1, 2020, to June 30, 2021) waves of the COVID-19 pandemic.

METHODS

An observational study of 309 consecutive patients (aged ≥18years) with severe COVID-19 supported by VV-ECMO was performed in 4 nationally commissioned ECMO centers in the United Kingdom.

RESULTS

Median age was 48 (19-75) years, and 70.6% were male. Probabilities of survival, thrombosis, and MB at 180 days in the overall cohort were 62.5% (193/309), 39.8% (123/309), and 30% (93/309), respectively. In multivariate analysis, an age of >55 years (hazard ratio [HR], 2.29; 95% CI, 1.33-3.93; P = .003) and an elevated creatinine level (HR, 1.91; 95% CI, 1.19-3.08; P = .008) were associated with increased mortality. Correction for duration of VV-ECMO support, arterial thrombosis alone (HR, 3.0; 95% CI, 1.5-5.9; P = .002) or circuit thrombosis alone (HR, 3.9; 95% CI, 2.4-6.3; P < .001) but not venous thrombosis increased mortality. MB during ECMO had a 3-fold risk (95% CI, 2.6-5.8, P < .001) of mortality. The first wave cohort had more males (76.7% vs 64%; P = .014), higher 180-day survival (71.1% vs 53.3%; P = .003), more venous thrombosis alone (46.4% vs 29.2%; P = .02), and lower circuit thrombosis (9.2% vs 28.1%; P < .001). The second wave cohort received more steroids (121/150 [80.6%] vs 86/159 [54.1%]; P < .0001) and tocilizumab (20/150 [13.3%] vs 4/159 [2.5%]; P = .005).

CONCLUSION

MB and thrombosis are frequent complications in patients on VV-ECMO and significantly increase mortality. Arterial thrombosis alone or circuit thrombosis alone increased mortality, while venous thrombosis alone had no effect. MB during ECMO support increased mortality by 3.9-fold.

A Comparison of Long-Term Outcomes in Patients Managed With Venovenous Extracorporeal Membrane Oxygenation in the First and Second Waves of the COVID-19 Pandemic in the United Kingdom

OBJECTIVES

Early studies of venovenous extracorporeal membrane oxygenation (ECMO) in COVID-19 have revealed similar outcomes to historical cohorts. Changes in the disease and treatments have led to differences in the patients supported on venovenous ECMO in the first and second waves. We aimed to compare these two groups in both the acute and follow-up phase.

DESIGN

Retrospective single-center cohort study comparing mortality at censoring date (November 30, 2021) and decannulation, patient characteristics, complications and lung function and quality of life (QOL-by European Quality of Life 5 Dimensions 3 Level Version) at first follow-up in patients supported on venovenous ECMO between wave 1 and wave 2 of the COVID-19 pandemic.

SETTING

Critical care department of a severe acute respiratory failure service.

PATIENTS

Patients supported on ECMO for COVID-19 between wave 1 (March 17, 2020, to August 31, 2020) and wave 2 (January 9, 2020, to May 25, 2021).

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

One hundred twenty-three patients were included in our analysis. Survival at censoring date (χ 2 , 6.35; p = 0.012) and decannulation (90.4% vs 70.0%; p < 0.001) was significantly lower in the second wave, while duration of ECMO run was longer (12.0 d [18.0-30.0 d] vs 29.5 d [15.5-58.3 d]; p = 0.005). Wave 2 patients had longer application of noninvasive ventilation (NIV) prior to ECMO and a higher frequency of barotrauma. Patient age and NIV use were independently associated with increased mortality (odds ratio 1.07 [1.01-1.14]; p = 0.025 and 3.37 [1.12-12.60]; p = 0.043, respectively). QOL and lung function apart from transfer coefficient of carbon monoxide corrected for hemoglobin was similar at follow-up across the waves.

CONCLUSIONS

Most patients with COVID-19 supported on ECMO in both waves survived in the short and longer term. At follow-up patients had similar lung function and QOL across the two waves. This suggests that ECMO has an ongoing role in the management of a carefully selected group of patients with COVID-19.

Impact of thromboprophylaxis on hospital acquired thrombosis following discharge in patients admitted with COVID-19: Multicentre observational study in the UK

Post-discharge thromboprophylaxis in patients admitted with COVID-19 remains controversial. We aimed to determine the impact of thromboprophylaxis on hospital acquired thrombosis (HAT) in patients (≥18 years) discharged following admission for COVID-19 in an observational study across 26 NHS Trusts in the UK (01.04.2020-31.12.2021). Overall, 8895 patients were included to the study: 971 patients were discharged with thromboprophylaxis and propensity score matched (PSM) with a desired ratio of 1:1, from patients discharged without thromboprophylaxis. Patients with heparin induced thrombocytopenia, major bleeding during admission and pregnant women were excluded. As expected from 1:1 PSM, no difference was observed in parameters between the two groups, including duration of hospital stay, except the thromboprophylaxis group had a significantly higher proportion who had received therapeutic dose anticoagulation during admission. There were no differences in the laboratory parameters especially D-dimers between the two groups at admission or discharge. Median duration of thromboprophylaxis following discharge from hospital was 4 weeks (1-8 weeks). No difference was found in HAT in patients discharged with TP versus no TP (1.3% vs. 0.92%, p = 0.52). Increasing age and smoking significantly increased the risk of HAT. Many patients in both cohorts had raised D-dimer at discharge but D-dimer was not associated with increased risk of HAT.

Hydroxychloroquine as an Immunomodulatory and Antithrombotic Treatment in Antiphospholipid Syndrome

Antiphospholipid syndrome (APS) is an acquired highly prothrombotic disorder in which thrombo-inflammatory antiphospholipid antibodies (aPL) cause thrombosis via multiple mechanisms, including endothelial damage and activation. Obstetric complications in APS are caused by placental thrombosis, inflammation and complement activation. Anticoagulation is poorly effective in some patients especially those with triple positive aPL who are at ~30% risk of thrombosis recurrence within 10 years. Increasing therapeutic anticoagulation intensity may be beneficial but leads to excess bleeding with serious complications, such as intracerebral haemorrhage. Nonetheless, anticoagulation is still the mainstay of treatment despite the autoimmune nature of APS. The antimalarial immunomodulatory drug hydroxychloroquine (HCQ) has been used for many years for the treatment of inflammatory rheumatic diseases. HCQ has complex pleiotropic mechanisms of action upon multiple cell types. The proposed biological processes that HCQ regulates support the hypothesis that it may be a successful adjunctive treatment in the prevention of recurrent thrombosis and pregnancy complications.

Autoimmune disease and COVID-19: a multicentre observational study in the United Kingdom

OBJECTIVE

To establish the demographic characteristics, laboratory findings and clinical outcomes in patients with autoimmune disease (AD) compared with a propensity-matched cohort of patients without AD admitted with COVID-19 to hospitals in the UK.

METHODS

This is a multicentre observational study across 26 NHS Trusts. Data were collected both retrospectively and prospectively using a predesigned standardized case record form. Adult patients (≥18 years) admitted between 1 April 2020 and 31 July 2020 were included.

RESULTS

Overall, 6288 patients were included to the study. Of these, 394 patients had AD prior to admission with COVID-19. Of 394 patients, 80 patients with SLE, RA or aPL syndrome were classified as severe rheumatologic AD. A higher proportion of those with AD had anaemia [240 (60.91%) vs 206 (52.28%), P = 0.015], elevated LDH [150 (38.08%) vs 43 (10.92%), P < 0.001] and raised creatinine [122 (30.96%) vs 86 (21.83%), P = 0.01], respectively. A significantly higher proportion of patients with severe rheumatologic AD had elevated CRP [77 (96.25%) vs 70 (87.5%), P = 0.044] and LDH [20 (25%) vs 6 (7.5%), P = 0.021]. Patients with severe rheumatologic AD had significantly higher mortality [32/80 (40%)] compared with propensity matched cohort of patients without AD [20/80 (25%), P = 0.043]. However, there was no difference in 180-day mortality between propensity-matched cohorts of patients with or without AD in general (P = 0.47).

CONCLUSIONS

Patients with severe rheumatologic AD had significantly higher mortality. Anaemia, renal impairment and elevated LDH were more frequent in patients with any AD while elevated CRP and LDH were more frequent in patients with severe rheumatologic AD both of which have been shown to associate with increased mortality in patients with COVID-19.

Complement activation during cardiopulmonary bypass and association with clinical outcomes

In this prospective, single-centre observational study of 30 patients undergoing cardiopulmonary bypass (CPB), the effect of unfractionated heparin (UFH), CPB surgery and protamine sulphate on complement and on post-operative blood loss were assessed. Although C3 and C4 levels decreased significantly immediately following the administration of UFH, C3a, C5a, Bb fragment and SC5b-9 remained unchanged. During CPB, C3 and C4 continued to fall whilst both alternative and classical pathways activation markers, Bb, C3a, C5a and SC5b-9 increased significantly. Protamine sulphate had no effect on classical pathway components or activation markers but decreased alternative pathway activation marker Bb. Over the 12-24 h post-surgery, both classical and alternative pathway activation markers returned to baseline, whilst C3 and C4 levels increased significantly but not to baseline values. Total drain volume 24 h after the surgery showed a moderate inverse correlation with post-protamine C3 (r = -0.46, p = 0.01) and C4 (r = -0.57, p = 0.0009) levels, whilst a moderate positive correlation was observed with post-protamine C3a (r = 0.46, p = 0.009), C5a (r = 0.37, p = 0.04) and SC5b-9 (r = 0.56, p = 0.001) levels but not with Bb fragment (r = 0.25, p = 0.17). Thus, inhibition of complement activation may be a therapeutic intervention to reduce post-operative blood in patients undergoing CPB.

Clinical outcomes and the impact of prior oral anticoagulant use in patients with coronavirus disease 2019 admitted to hospitals in the UK - a multicentre observational study

Coagulation dysfunction and thrombosis are major complications in patients with coronavirus disease 2019 (COVID-19). Patients on oral anticoagulants (OAC) prior to diagnosis of COVID-19 may therefore have better outcomes. In this multicentre observational study of 5 883 patients (≥18 years) admitted to 26 UK hospitals between 1 April 2020 and 31 July 2020, overall mortality was 29·2%. Incidences of thrombosis, major bleeding (MB) and multiorgan failure (MOF) were 5·4%, 1·7% and 3·3% respectively. The presence of thrombosis, MB, or MOF was associated with a 1·8, 4·5 or 5·9-fold increased risk of dying, respectively. Of the 5 883 patients studied, 83·6% (n = 4 920) were not on OAC and 16·4% (n = 963) were taking OAC at the time of admission. There was no difference in mortality between patients on OAC vs no OAC prior to admission when compared in an adjusted multivariate analysis [hazard ratio (HR) 1·05, 95% confidence interval (CI) 0·93-1·19; P = 0·15] or in an adjusted propensity score analysis (HR 0·92 95% CI 0·58-1·450; P = 0·18). In multivariate and adjusted propensity score analyses, the only significant association of no anticoagulation prior to diagnosis of COVID-19 was admission to the Intensive-Care Unit (ICU) (HR 1·98, 95% CI 1·37-2·85). Thrombosis, MB, and MOF were associated with higher mortality. Our results indicate that patients may have benefit from prior OAC use, especially reduced admission to ICU, without any increase in bleeding.

Impact of major bleeding and thrombosis on 180-day survival in patients with severe COVID-19 supported with veno-venous extracorporeal membrane oxygenation in the United Kingdom: a multicentre observational study

Bleeding and thrombosis are major complications in patients supported with extracorporeal membrane oxygenation (ECMO). In this multicentre observational study of 152 consecutive patients (≥18 years) with severe COVID‐19 supported by veno‐venous (VV) ECMO in four UK commissioned centres during the first wave of the COVID‐19 pandemic (1 March to 31 May 2020), we assessed the incidence of major bleeding and thrombosis and their association with 180‐day mortality. Median age (range) was 47 years (23–65) and 75% were male. Overall, the 180‐day survival was 70·4% (107/152). The rate of major bleeding was 30·9% (47/152), of which intracranial bleeding (ICH) was 34% (16/47). There were 96 thrombotic events (63·1%) consisting of venous 44·7% [68/152 of which 66·2% were pulmonary embolism (PE)], arterial 18·6% (13/152) and ECMO circuit thrombosis 9·9% (15/152). In multivariate analysis, only raised lactate dehydrogenase (LDH) at the initiation of VV ECMO was associated with an increased risk of thrombosis [hazard ratio (HR) 1·92, 95% CI 1·21‐3·03]. Major bleeding and ICH were associated with 3·87‐fold (95% CI 2·10–7·23) and 5·97‐fold [95% confidence interval (CI) 2·36–15·04] increased risk of mortality and PE with a 2·00‐fold (95% CI1·09–3·56) risk of mortality. This highlights the difficult balancing act often encountered when managing coagulopathy in COVID‐19 patients supported with ECMO.

Dual-Energy CT Pulmonary Angiography (DECTPA) Quantifies Vasculopathy in Severe COVID-19 Pneumonia

BACKGROUND

The role of dual energy computed tomographic pulmonary angiography (DECTPA) in revealing vasculopathy in coronavirus disease 2019 (COVID-19) has not been fully explored.

PURPOSE

To evaluate the relationship between DECTPA and disease duration, right ventricular dysfunction (RVD), lung compliance, D-dimer and obstruction index in COVID-19 pneumonia.

MATERIALS AND METHODS

This institutional review board approved this retrospective study, and waived the informed consent requirement. Between March-May 2020, 27 consecutive ventilated patients with severe COVID-19 pneumonia underwent DECTPA to diagnose pulmonary thrombus (PT); 11 underwent surveillance DECTPA 14 ±11.6 days later. Qualitative and quantitative analysis of perfused blood volume (PBV) maps recorded: i) perfusion defect 'pattern' (wedge-shaped, mottled or amorphous), ii) presence of PT and CT obstruction index (CTOI) and iii) PBV relative to pulmonary artery enhancement (PBV/PAenh); PBV/PAenh was also compared with seven healthy volunteers and correlated with D-Dimer and CTOI.

RESULTS

Amorphous (n=21), mottled (n=4), and wedge-shaped (n=2) perfusion defects were observed (M=20; mean age=56 ±8.7 years). Mean extent of perfusion defects=36.1%±17.2. Acute PT was present in 11/27(40.7%) patients. Only wedge-shaped defects corresponded with PT (2/27, 7.4%). Mean CTOI was 2.6±5.4 out of 40. PBV/PAenh (18.2 ±4.2%) was lower than in healthy volunteers (27 ±13.9%, p = 0.002). PBV/PAenh correlated with disease duration (β = 0.13, p = 0.04), and inversely correlated with RVD (β = -7.2, p = 0.001), persisting after controlling for confounders. There were no linkages between PBV/PAenh and D-dimer or CTOI.

CONCLUSION

Perfusion defects and decreased PBV/PAenh are prevalent in severe COVID-19 pneumonia. PBV/PAenh correlates with disease duration and inversely correlates with RVD. PBV/PAenh may be an important marker of vasculopathy in severe COVID-19 pneumonia even in the absence of arterial thrombus.

Rescue therapy with thrombolysis in patients with severe COVID-19-associated acute respiratory distress syndrome

Acute respiratory distress syndrome in patients with Coronavirus disease 19 is associated with an unusually high incidence of pulmonary embolism and microthrombotic disease, with evidence for reduced fibrinolysis. We describe seven patients requiring invasive ventilation for COVID-19-associated acute respiratory distress syndrome with pulmonary thromboembolic disease, pulmonary hypertension ± severe right ventricular dysfunction on echocardiography, who were treated with alteplase as fibrinolytic therapy. All patients were non-smokers, six (86%) were male and median age was 56.7 (50-64) years. They had failed approaches including therapeutic anticoagulation, prone ventilation (n = 4), inhaled nitric oxide (n = 5) and nebulised epoprostenol (n = 2). The median duration of mechanical ventilation prior to thrombolysis was seven (5-11) days. Systemic alteplase was administered to six patients (50 mg or 90 mg bolus over 120 min) at 16 (10-22) days after symptom onset. All received therapeutic heparin pre- and post-thrombolysis, without intracranial haemorrhage or other major bleeding. Alteplase improved PaO2/FiO2 ratio (from 97.0 (86.3-118.6) to 135.6 (100.7-171.4), p = 0.03) and ventilatory ratio (from 2.76 (2.09-3.49) to 2.36 (1.82-3.05), p = 0.011) at 24 h. Echocardiographic parameters at two (1-3) days (n = 6) showed right ventricular systolic pressure (RVSP) was 63 (50.3-75) then 57 (49-66) mmHg post-thrombolysis (p = 0.26), tricuspid annular planar systolic excursion (TAPSE) was unchanged (from 18.3 (11.9-24.5) to 20.5 (15.4-24.2) mm, p = 0.56) and right ventricular fractional area change (from 15.4 (11.1-35.6) to 31.2 (16.4-33.1)%, p = 0.09). At seven (1-13) days after thrombolysis, using dual energy computed tomography imaging (n = 3), average relative peripheral lung enhancement increased from 12.6 to 21.6% (p = 0.06). In conclusion, thrombolysis improved PaO2/FiO2 ratio and ventilatory ratio at 24 h as rescue therapy in patients with right ventricular dysfunction due to COVID-19-associated ARDS despite maximum therapy, as part of a multimodal approach, and warrants further study.

Pulmonary Angiopathy in Severe COVID-19: Physiologic, Imaging, and Hematologic Observations

Rationale: Clinical and epidemiologic data in coronavirus disease (COVID-19) have accrued rapidly since the outbreak, but few address the underlying pathophysiology.Objectives: To ascertain the physiologic, hematologic, and imaging basis of lung injury in severe COVID-19 pneumonia.Methods: Clinical, physiologic, and laboratory data were collated. Radiologic (computed tomography (CT) pulmonary angiography [n = 39] and dual-energy CT [DECT, n = 20]) studies were evaluated: observers quantified CT patterns (including the extent of abnormal lung and the presence and extent of dilated peripheral vessels) and perfusion defects on DECT. Coagulation status was assessed using thromboelastography.Measurements and Results: In 39 consecutive patients (male:female, 32:7; mean age, 53 ± 10 yr [range, 29-79 yr]; Black and minority ethnic, n = 25 [64%]), there was a significant vascular perfusion abnormality and increased physiologic dead space (dynamic compliance, 33.7 ± 14.7 ml/cm H2O; Murray lung injury score, 3.14 ± 0.53; mean ventilatory ratios, 2.6 ± 0.8) with evidence of hypercoagulability and fibrinolytic "shutdown". The mean CT extent (±SD) of normally aerated lung, ground-glass opacification, and dense parenchymal opacification were 23.5 ± 16.7%, 36.3 ± 24.7%, and 42.7 ± 27.1%, respectively. Dilated peripheral vessels were present in 21/33 (63.6%) patients with at least two assessable lobes (including 10/21 [47.6%] with no evidence of acute pulmonary emboli). Perfusion defects on DECT (assessable in 18/20 [90%]) were present in all patients (wedge-shaped, n = 3; mottled, n = 9; mixed pattern, n = 6).Conclusions: Physiologic, hematologic, and imaging data show not only the presence of a hypercoagulable phenotype in severe COVID-19 pneumonia but also markedly impaired pulmonary perfusion likely caused by pulmonary angiopathy and thrombosis.