Although respiratory failure and hypoxaemia are the main manifestations of COVID-19, kidney involvement is also common. Available evidence supports a number of potential pathophysiological pathways through which acute kidney injury (AKI) can develop in the context of SARS-CoV-2 infection. Histopathological findings have highlighted both similarities and differences between AKI in patients with COVID-19 and in those with AKI in non-COVID-related sepsis. Acute tubular injury is common, although it is often mild, despite markedly reduced kidney function. Systemic haemodynamic instability very likely contributes to tubular injury. Despite descriptions of COVID-19 as a cytokine storm syndrome, levels of circulating cytokines are often lower in patients with COVID-19 than in patients with acute respiratory distress syndrome with causes other than COVID-19. Tissue inflammation and local immune cell infiltration have been repeatedly observed and might have a critical role in kidney injury, as might endothelial injury and microvascular thrombi. Findings of high viral load in patients who have died with AKI suggest a contribution of viral invasion in the kidneys, although the issue of renal tropism remains controversial. An impaired type I interferon response has also been reported in patients with severe COVID-19. In light of these observations, the potential pathophysiological mechanisms of COVID-19-associated AKI may provide insights into therapeutic strategies.

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Pathophysiology of COVID-19-associated acute kidney injury.

https://doi.org/10.1016/j.jacc.2022.02.003

2022 ACC Expert Consensus Decision Pathway on Cardiovascular Sequelae of COVID-19 in Adults: Myocarditis and Other Myocardial Involvement, Post-Acute Sequelae of SARS-CoV-2 Infection, and Return to Play

Abstract Emerging as a new epidemic, long COVID or post-acute sequelae of coronavirus disease 2019 (COVID-19), a condition characterized by the persistence of COVID-19 symptoms beyond 3 months, is anticipated to substantially alter the lives of millions of people globally. Cardiopulmonary symptoms including chest pain, shortness of breath, fatigue, and autonomic manifestations such as postural orthostatic tachycardia are common and associated with significant disability, heightened anxiety, and public awareness. A range of cardiovascular (CV) abnormalities has been reported among patients beyond the acute phase and include myocardial inflammation, myocardial infarction, right ventricular dysfunction, and arrhythmias. Pathophysiological mechanisms for delayed complications are still poorly understood, with a dissociation seen between ongoing symptoms and objective measures of cardiopulmonary health. COVID-19 is anticipated to alter the long-term trajectory of many chronic cardiac diseases which are abundant in those at risk of severe disease. In this review, we discuss the definition of long COVID and its epidemiology, with an emphasis on cardiopulmonary symptoms. We further review the pathophysiological mechanisms underlying acute and chronic CV injury, the range of post-acute CV sequelae, and impact of COVID-19 on multiorgan health. We propose a possible model for referral of post-COVID-19 patients to cardiac services and discuss future directions including research priorities and clinical trials that are currently underway to evaluate the efficacy of treatment strategies for long COVID and associated CV sequelae.

https://academic.oup.com/eurheartj/advance-article-pdf/doi/10.1093/eurheartj/ehac031/42541089/ehac031.pdf

Long COVID: post-acute sequelae of COVID-19 with a cardiovascular focus

BET inhibition blocks inflammation-induced cardiac dysfunction and SARS-CoV-2 infection.

Post-Covid-19 Tachycardia Syndrome: A distinct phenotype of Post-acute Covid-19 Syndrome.

Background Troponin elevation is common in hospitalized COVID-19 patients, but underlying aetiologies are ill-defined. We used multi-parametric cardiovascular magnetic resonance (CMR) to assess myocardial injury in recovered COVID-19 patients. Methods and results One hundred and forty-eight patients (64 ± 12 years, 70% male) with severe COVID-19 infection [all requiring hospital admission, 48 (32%) requiring ventilatory support] and troponin elevation discharged from six hospitals underwent convalescent CMR (including adenosine stress perfusion if indicated) at median 68 days. Left ventricular (LV) function was normal in 89% (ejection fraction 67% ± 11%). Late gadolinium enhancement and/or ischaemia was found in 54% (80/148). This comprised myocarditis-like scar in 26% (39/148), infarction and/or ischaemia in 22% (32/148) and dual pathology in 6% (9/148). Myocarditis-like injury was limited to three or less myocardial segments in 88% (35/40) of cases with no associated LV dysfunction; of these, 30% had active myocarditis. Myocardial infarction was found in 19% (28/148) and inducible ischaemia in 26% (20/76) of those undergoing stress perfusion (including 7 with both infarction and ischaemia). Of patients with ischaemic injury pattern, 66% (27/41) had no past history of coronary disease. There was no evidence of diffuse fibrosis or oedema in the remote myocardium (T1: COVID-19 patients 1033 ± 41 ms vs. matched controls 1028 ± 35 ms; T2: COVID-19 46 ± 3 ms vs. matched controls 47 ± 3 ms). Conclusions During convalescence after severe COVID-19 infection with troponin elevation, myocarditis-like injury can be encountered, with limited extent and minimal functional consequence. In a proportion of patients, there is evidence of possible ongoing localized inflammation. A quarter of patients had ischaemic heart disease, of which two-thirds had no previous history. Whether these observed findings represent pre-existing clinically silent disease or de novo COVID-19-related changes remain undetermined. Diffuse oedema or fibrosis was not detected.

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Patterns of myocardial injury in recovered troponin-positive COVID-19 patients assessed by cardiovascular magnetic resonance.

BackgroundComplications following SARS-CoV-2 infection require simultaneous characterisation and management to plan policy and health system responses. We describe the 12-month experience of the first UK dedicated Post-COVID clinical service to include both hospitalised and non-hospitalised patients. MethodsIn a single-centre, observational analysis, we report outcomes for 1325 individuals assessed in the University College London Hospitals NHS Foundation Trust Post-COVID service between April 2020 and April 2021. Demography, symptoms, comorbidities, investigations, treatments, functional recovery, specialist referral and rehabilitation were compared by referral route ("post hospitalisation", PH; "non-hospitalised", NH; and "post emergency department", PED). Symptoms associated with poor recovery or inability to return to work full-time were assessed using multivariable logistic regression. Findings1325 individuals were assessed (PH 547 [41.3%], PED 212 [16%], NH 566 [42.7%]. Compared with PH and PED groups, NH were younger (median 44.6 [35.6-52.8] vs 58.3 [47.0-67.7] and 48.5 [39.4-55.7] years), more likely to be female (68.2%, 43.0% and 59.9%), less likely to be from an ethnic minority (30.9%, 52.7% and 41.0%) and seen later after symptom onset (median [IQR]:194 [118-298], 69 [51-111] and 76 [55-128] days) (all p<0.0001). NH patients had similar rates of onward specialist referral as PH and PED groups (18.7%, 16.1% and 18.9%, p=0.452), and were more likely to require support for breathlessness (23.7%, 5.5% and 15.1%, p<0.001) and fatigue (17.8%, 4.8%, 8.0%, p<0.001). Hospitalised patients had higher rates of pulmonary emboli, persistent lung interstitial abnormalities, and other organ impairment. 716 (54.0%) individuals reported <75% of optimal health (median [IQR] 70% [55%-85%]). Overall, less than half of employed individuals felt able to return to work full-time at first assessment. InterpretationSymptoms following SARS-CoV-2 infection were significant in both post- and non-hospitalised patients, with significant ongoing healthcare needs and utilisation. Trials of interventions and patient-centred pathways for diagnostic and treatment approaches are urgently required. FundingUCLH/UCL BRC Research in contextO_ST_ABSPrevious evidenceC_ST_ABSLong COVID and post-COVID syndrome were first identified in April 2020. We searched PubMed and medrxiv for articles published up to April 30th, 2021, using the keywords "long COVID", "post-COVID syndrome", "persistent symptoms", "hospitalised", "community" and "non-hospitalised". We identified 17 articles and 7 systematic reviews. Fifteen studies have considered symptoms, multi-organ or functional impairment but only one study to-date has considered all these variables in non-hospitalised COVID patients. No studies have compared symptom burden and management between non-hospitalised and hospitalised individuals as systematically assessed and managed in a dedicated post-COVID service. Added value of this studyFor the first time, we report the baseline characteristics, investigation and outcomes of initial assessment of all eligible patients in a dedicated multi-professional post-COVID service, including 547 post-hospitalisation, 566 non-hospitalised and 212 patients discharged from emergency department. Despite relatively low comorbidity and risk factor burden in non-hospitalised patients, we show that both non-hospitalised and hospitalised patients presenting with persistent symptoms after SARS-CoV2 infection have high rates of functional impairment, specialist referral and rehabilitation, even 6-12 months after the acute infection. These real-world data will inform models of care during and beyond the pandemic. Implications of all the available evidenceThe significant, long-lasting health and social consequences of SARS-CoV-2 infection are not confined to those who required hospitalisation. As with other long-term conditions, care of patients experiencing Long COVID or specific end-organ effects require consistent, integrated, patient-centred approaches to investigation and management. At public health and policy level, burden of post-COVID morbidity demands renewed focus on effective infection suppression for all age groups.

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Toby Hillman

Papers

Patterns of myocardial injury in recovered troponin-positive COVID-19 patients assessed by cardiovascular magnetic resonance.

Post-COVID assessment in a specialist clinical service: a 12-month, single-centre analysis of symptoms and healthcare needs in 1325 individuals.