Role of Endothelium in Cardiovascular Sequelae of Long COVID

Berberine and its derivatives: mechanisms of action in myocardial vascular endothelial injury - a review

Myocardial vascular endothelial injury serves as a crucial inducer of cardiovascular diseases. Mechanisms such as endoplasmic reticulum stress, apoptosis, inflammation, oxidative stress, autophagy, platelet dysfunction, and gut microbiota imbalance are intimately linked to this condition. Berberine and its derivatives have demonstrated potential in modulating these mechanisms. This article reviews the pathogenesis of endothelial injury in myocardial vessels, the pharmacological effects of berberine and its derivatives, particularly their interactions with targets implicated in vascular endothelial injury. Furthermore, it discusses clinical applications, methods to enhance bioavailability, and toxicity concerns, aiming to lay a foundation for the development of BBR as a therapeutic agent for cardiovascular diseases.

The negative effects of long COVID-19 on cardiovascular health and implications for the presurgical examination

CONTEXT

In 2019, emergence of the novel and communicable severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection took scientific communities by surprise and imposed significant burden on healthcare systems globally. Although the advent of this disease piqued the interest of academic centers, healthcare systems, and the general public, there is still much yet to be elucidated regarding epidemiology, pathophysiology, and long-term impacts of coronavirus disease 2019 (COVID-19). It has been established that long COVID-19 can impact multiple organ systems, including the cardiovascular system, unfavorably. Although the pathophysiology of this damage is not well understood, adverse sequelae may range from chest pain and arrhythmias to heart failure (HF), myocardial infarction, or sudden cardiac death. For any postacute COVID-19 patient requiring a surgical procedure, the potential for cardiac injury secondary to long COVID-19 must be considered in the preoperative cardiac examination.

OBJECTIVES

This literature review serves to add to the growing body of literature exploring postacute cardiovascular outcomes of COVID-19, with a focus on presurgical cardiac clearance in the adult patient. Specifically, this review studies the prevalence of cardiovascular symptomatology including chest pain, arrhythmias, blood pressure changes, myo-/pericarditis, HF, cardiomyopathy, orthostatic intolerance, and thromboembolism. Although current evidence is scarce in both quality and quantity, it is the goal that this review will highlight the negative impacts of long COVID-19 on cardiovascular health and encourage providers to be cognizant of potential sequelae in the context of the presurgical examination.

METHODS

For this study, peer-reviewed and journal-published articles were selected based on established inclusion and exclusion criteria to address the question "How does long COVID-19 impact the presurgical cardiac examination of an adult scheduled to undergo a noncardiac procedure?" Inclusion criteria included human studies conducted in adult patients and published in peer-reviewed journals up until May 2024 examining the effects of long-COVID-19 infection on the cardiovascular system. Exclusion criteria eliminated unpublished reports, preprints, duplicate articles, literature regarding coronavirus strains other than COVID-19, studies regarding post-COVID-19 vaccination complications, animal studies, and studies conducted in people younger than 18 years of age. A total of 6,675 studies were retrieved from PubMed and Google Scholar. Following screening, 60 studies were included in final consideration.

RESULTS

Cardiovascular symptoms of postacute COVID-19 infection were encountered with the following percentages prevalence (total numbers of articles mentioning symptom/total number of articles [60]): chest pain (83.3), arrhythmias (88.3), hypertension (40.0), hypotension (16.7), myocarditis (80.0), pericarditis (51.7), HF (70.0), cardiomyopathy (55.0), orthostatic intolerance (56.7), and thromboembolic events (85.0).

CONCLUSIONS

The presence of persisting COVID symptoms may negatively impact the patient's physical examination, blood tests, electrocardiogram (ECG), imaging, and/or echocardiogram. Cardiac conditions associated with long COVID require special attention in the context of the presurgical candidate due to an increased risk of sudden cardiac death, myocarditis, stroke, and myocardial infarction - even in those who were healthy prior to acute COVID-19 infection. Until more specific scientific evidence comes to light, care of these patients should be viewed through the prism of the best practices already in use and clinicians should maintain a low threshold to pursue more extensive cardiac workup prior to surgery.

Effects of COVID-19 Infection on Endothelial Vascular Function

Most studies analyzing data from patients who experienced at least one episode of acute COVID-19 infection have attributed the cascade of immediate and late complications to disruption of the inflammatory system and neutrophil activity in particular. Among the various functions of neutrophils is the release of pro-inflammatory mediators, including interleukin-6 (IL-6). Oxidative stress induced by pro-inflammatory mediators secreted by neutrophils leads to vascular endothelial dysfunction. Neutrophil counts and the neutrophil-to-lymphocyte ratio (NLR) are directly associated with COVID-19 patient survival, with higher values correlating with increased mortality. To assess endothelial dysfunction secondary to COVID-19 infection, we conducted a retrospective study involving two patient cohorts, each comprising 99 participants: one group with a history of COVID-19 infection and another without. The study aimed to demonstrate the presence of endothelial dysfunction in patients with moderate COVID-19 infection using flow-mediated dilatation (FMD) of the brachial artery and to evaluate its correlation with key inflammatory markers (erythrocyte sedimentation rate-ESR, fibrinogen, NLR, IL-6). FMD values were significantly reduced (p < 0.0001) in post-COVID-19 patients compared to those without prior infection. ESR (p < 0.0001), fibrinogen (p < 0.0001), C-reactive protein (CRP) (p < 0.0001), leukocyte count (p < 0.0001), and granulocyte count (p < 0.0001) were inversely correlated with FMD values. Among post-COVID-19 patients, all analyzed parameters demonstrated a statistically significant impact on FMD, with ESR showing the strongest effect, accounting for nearly 63% of the dependency. ANOVA testing confirmed an inverse association between NLR quartiles and FMD, as well as between IL-6 levels and FMD. In conclusion, this study highlights the presence of endothelial dysfunction in post-COVID-19 patients, as assessed by FMD, and demonstrates statistically significant inverse correlations between FMD values, IL-6 levels, and the neutrophil-to-lymphocyte ratio.

Human herpesvirus reactivation and its potential role in the pathogenesis of post-acute sequelae of SARS-CoV-2 infection

The emergence of SARS-CoV-2 has precipitated a global pandemic with substantial long-term health implications, including the condition known as post-acute sequelae of SARS-CoV-2 infection (PASC), commonly referred to as Long COVID. PASC is marked by persistent symptoms such as fatigue, neurological issues, and autonomic dysfunction that persist for months beyond the acute phase of COVID-19. This review examines the potential role of herpesvirus reactivation, specifically Epstein-Barr virus (EBV) and cytomegalovirus (CMV), in the pathogenesis of PASC. Elevated antibody titers and specific T cell responses suggest recent herpesvirus reactivation in some PASC patients, although viremia is not consistently detected. SARS-CoV-2 exhibits endothelial trophism, directly affecting the vascular endothelium and contributing to microvascular pathologies. These pathologies are significant in PASC, where microvascular dysfunction may underlie various chronic symptoms. Similarly, herpesviruses like CMV also exhibit endothelial trophism, which may exacerbate endothelial damage when reactivated. Evidence suggests that EBV and CMV reactivation could indirectly contribute to the immune dysregulation, immunosenescence, and autoimmune responses observed in PASC. Additionally, EBV may play a role in the genesis of neurological symptoms through creating mitochondrial dysfunction, though direct confirmation remains elusive. The reviewed evidence suggests that while herpesviruses may not play a direct role in the pathogenesis of PASC, their potential indirect effects, especially in the context of endothelial involvement, warrant further investigation.

Cerebromicrovascular mechanisms contributing to long COVID: implications for neurocognitive health

Long COVID (also known as post-acute sequelae of SARS-CoV-2 infection [PASC] or post-COVID syndrome) is characterized by persistent symptoms that extend beyond the acute phase of SARS-CoV-2 infection, affecting approximately 10% to over 30% of those infected. It presents a significant clinical challenge, notably due to pronounced neurocognitive symptoms such as brain fog. The mechanisms underlying these effects are multifactorial, with mounting evidence pointing to a central role of cerebromicrovascular dysfunction. This review investigates key pathophysiological mechanisms contributing to cerebrovascular dysfunction in long COVID and their impacts on brain health. We discuss how endothelial tropism of SARS-CoV-2 and direct vascular infection trigger endothelial dysfunction, impaired neurovascular coupling, and blood-brain barrier disruption, resulting in compromised cerebral perfusion. Furthermore, the infection appears to induce mitochondrial dysfunction, enhancing oxidative stress and inflammation within cerebral endothelial cells. Autoantibody formation following infection also potentially exacerbates neurovascular injury, contributing to chronic vascular inflammation and ongoing blood-brain barrier compromise. These factors collectively contribute to the emergence of white matter hyperintensities, promote amyloid pathology, and may accelerate neurodegenerative processes, including Alzheimer's disease. This review also emphasizes the critical role of advanced imaging techniques in assessing cerebromicrovascular health and the need for targeted interventions to address these cerebrovascular complications. A deeper understanding of the cerebrovascular mechanisms of long COVID is essential to advance targeted treatments and mitigate its long-term neurocognitive consequences.

Pinaffi-Langley AC, Peterfi A, Mukli P, Detwiler S, Olay L, Kaposzta Z, Smith K, Kirkpatrick AC, Saleh Velez F, Tarantini S, Csiszar A, Ungvari ZI, Prodan CI, Yabluchanskiy A. COVID-19 Exacerbates Neurovascular Uncoupling and Contributes to Endothelial Dysfunction in Patients with Mild Cognitive Impairment

Mild cognitive impairment (MCI) affects nearly 20% of older adults worldwide, with no targetable interventions for prevention. COVID-19 adversely affects cognition, with >70% of older adults with Long COVID presenting with cognitive complaints. Neurovascular coupling (NVC), an essential mechanism of cognitive function, declines with aging and is further attenuated in neurocognitive disorders. The effect of COVID-19 on NVC responses has yet to be addressed in older adults who are vulnerable to dementia progression. Participants with MCI and a history of COVID-19 (COV+, N = 31) and MCI participants with no history of infection (COV- N = 11) participated in this cross-sectional study to determine if COVID-19 affects cerebrocortical NVC responses and vascular function. Functional near-infrared spectroscopy was used to measure cerebrocortical NVC responses, and endothelial function was assessed via insonation of the brachial artery during a flow-mediated dilation protocol. NVC responses were elicited by the working memory n-back paradigm. NVC in the left dorsolateral prefrontal cortex and endothelial function was decreased in the COV+ group compared to the COV- group. These data provide mechanistic insight into how COVID-19 may exacerbate long-term cognitive sequela seen in older adults, highlighting the urgent need for further research and clinical trials to explore novel therapeutic interventions aimed at preserving/restoring NVC.

Post-acute sequelae of SARS-CoV-2 infection (Long COVID) in older adults

Long COVID, also known as PASC (post-acute sequelae of SARS-CoV-2), is a complex infection-associated chronic condition affecting tens of millions of people worldwide. Many aspects of this condition are incompletely understood. Among them is how this condition may manifest itself in older adults and how it might impact the older population. Here, we briefly review the current understanding of PASC in the adult population and examine what is known on its features with aging. Finally, we outline the major gaps and areas for research most germane to older adults.

Musculoskeletal, Pulmonary, and Cardiovascular COVID-19 Sequelae in the Context of Firefighter Occupational Health: A Narrative Review

For most individuals infected with SARS-CoV-2, the acute illness resolves completely. However, for millions of people, symptoms or sequelae from COVID-19 recur or persist for months to years after infection. Post-COVID-19 sequelae are wide-ranging, often affecting the musculoskeletal, pulmonary, and cardiovascular systems. All who experience post-COVID-19 sequelae face significant challenges navigating home and work life. Occupations such as firefighting, however, are of particular concern given the strenuous nature of a job that relies on a healthy musculoskeletal, pulmonary, and cardiovascular system. Research has documented significant musculoskeletal impairment (including muscle weakness, pain, and fatigue), respiratory dysfunction (including reduced lung function, interstitial disease, and diffusion abnormalities), cardiovascular conditions (including cardiac events, ischemic disease, dysrhythmias, and infectious diseases), and diminished cardiorespiratory fitness that continues for months to years in some individuals. These persistent post-COVID-19 conditions may affect a firefighter's ability to return to work, function at full capacity while at work, and potentially compromise firefighter health and public safety. This review, therefore, explores musculoskeletal, pulmonary, and cardiovascular sequelae post-COVID-19 and the impact of these sequelae on firefighter health and occupational readiness.

Improving quality in adult long covid services: Findings from the LOCOMOTION quality improvement collaborative

The protracted form of COVID-19 known as 'long covid' was first described in 2020. Its symptoms, course and prognosis vary widely; some patients have a multi-system, disabling and prolonged illness. In 2021, ring-fenced funding was provided to establish 90 long covid clinics in England; some clinics were also established in Scotland and Wales. The NIHR-funded LOCOMOTION project implemented a UK-wide quality improvement collaborative involving ten of these clinics, which ran from 2021 to 2023. At regular online meetings held approximately 8-weekly, participants prioritised topics, discussed research evidence and guidelines, and presented exemplar case histories and clinic audits. A patient advisory group also held a priority-setting exercise, participated in quality meetings and undertook a service evaluation audit. The goal of successive quality improvement cycles aimed at changing practice to align with evidence was sometimes hard to achieve because definitive evidence did not yet exist in this new condition; many patients had comorbidities; and clinics were practically constrained in various ways. Nevertheless, much progress was made and a series of 'best practice' guides was produced, covering general assessment and management; breathing difficulties; orthostatic tachycardia and other autonomic symptoms; fatigue and cognitive impairment; and vocational rehabilitation. This paper summarises key findings with the frontline clinician in mind.

Long COVID: a clinical update

Post-COVID-19 condition (also known as long COVID) is generally defined as symptoms persisting for 3 months or more after acute COVID-19. Long COVID can affect multiple organ systems and lead to severe and protracted impairment of function as a result of organ damage. The burden of this disease, both on the individual and on health systems and national economies, is high. In this interdisciplinary Review, with a coauthor with lived experience of severe long COVID, we sought to bring together multiple streams of literature on the epidemiology, pathophysiology (including the hypothesised mechanisms of organ damage), lived experience and clinical manifestations, and clinical investigation and management of long COVID. Although current approaches to long COVID care are largely symptomatic and supportive, recent advances in clinical phenotyping, deep molecular profiling, and biomarker identification might herald a more mechanism-informed and personally tailored approach to clinical care. We also cover the organisation of services for long COVID, approaches to preventing long COVID, and suggestions for future research.

New Insights into Endothelial Dysfunction in Cardiometabolic Diseases: Potential Mechanisms and Clinical Implications

The endothelium is a monocellular layer covering the inner surface of blood vessels. It maintains vascular homeostasis regulating vascular tone and permeability and exerts anti-inflammatory, antioxidant, anti-proliferative, and anti-thrombotic functions. When the endothelium is exposed to detrimental stimuli including hyperglycemia, hyperlipidemia, and neurohormonal imbalance, different biological pathways are activated leading to oxidative stress, endothelial dysfunction, increased secretion of adipokines, cytokines, endothelin-1, and fibroblast growth factor, and reduced nitric oxide production, leading eventually to a loss of integrity. Endothelial dysfunction has emerged as a hallmark of dysmetabolic vascular impairment and contributes to detrimental effects on cardiac metabolism and diastolic dysfunction, and to the development of cardiovascular diseases including heart failure. Different biomarkers of endothelial dysfunction have been proposed to predict cardiovascular diseases in order to identify microvascular and macrovascular damage and the development of atherosclerosis, particularly in metabolic disorders. Endothelial dysfunction also plays an important role in the development of severe COVID-19 and cardiovascular complications in dysmetabolic patients after SARS-CoV-2 infection. In this review, we will discuss the biological mechanisms involved in endothelial dysregulation in the context of cardiometabolic diseases as well as the available and promising biomarkers of endothelial dysfunction in clinical practice.

Long COVID or Post-COVID-19 Condition: Past, Present and Future Research Directions

The presence of symptoms after an acute SARS-CoV-2 infection (long-COVID) has become a worldwide healthcare emergency but remains underestimated and undertreated due to a lack of recognition of the condition and knowledge of the underlying mechanisms. In fact, the prevalence of post-COVID symptoms ranges from 50% during the first months after the infection up to 20% two-years after. This perspective review aimed to map the existing literature on post-COVID symptoms and to identify gaps in the literature to guide the global effort toward an improved understanding of long-COVID and suggest future research directions. There is a plethora of symptomatology that can be due to COVID-19; however, today, there is no clear classification and definition of this condition, termed long-COVID or post-COVID-19 condition. The heterogeneity in the symptomatology has led to the presence of groups/clusters of patients, which could exhibit different risk factors and different mechanisms. Viral persistence, long-lasting inflammation, immune dysregulation, autoimmune reactions, reactivation of latent infections, endothelial dysfunction and alteration in gut microbiota have been proposed as potential mechanisms explaining the complexity of long-COVID. In such an equation, viral biology (e.g., re-infections, SARS-CoV-2 variants), host biology (e.g., genetics, epigenetics) and external factors (e.g., vaccination) should be also considered. These various factors will be discussed in the current perspective review and future directions suggested.

SGLT2 Inhibitors in Long COVID Syndrome: Is There a Potential Role?

The coronavirus disease (COVID)-19 has turned into a pandemic causing a global public health crisis. While acute COVID-19 mainly affects the respiratory system and can cause acute respiratory distress syndrome, an association with persistent inflammatory stress affecting different organ systems has been elucidated in long COVID syndrome (LCS). Increased severity and mortality rates have been reported due to cardiophysiological and metabolic systemic disorders as well as multiorgan failure in COVID-19, additionally accompanied by chronic dyspnea and fatigue in LCS. Hence, novel therapies have been tested to improve the outcomes of LCS of which one potential candidate might be sodium-glucose cotransporter 2 (SGLT2) inhibitors. The aim of this narrative review was to discuss rationales for investigating SGLT2 inhibitor therapy in people suffering from LCS. In this regard, we discuss their potential positive effects-next to the well described "cardio-renal-metabolic" conditions-with a focus on potential anti-inflammatory and beneficial systemic effects in LCS. However, potential beneficial as well as potential disadvantageous effects of SGLT2 inhibitors on the prevalence and long-term outcomes of COVID-19 will need to be established in ongoing research.

Mid-Regional Proadrenomedullin in COVID-19-May It Act as a Predictor of Prolonged Cardiovascular Complications?

The rising prevalence of cardiovascular disease (CVD) and the impact of the SARS-CoV-2 pandemic have both led to increased mortality rates, affecting public health and the global economy. Therefore, it is essential to find accessible, non-invasive prognostic markers capable of identifying patients at high risk. One encouraging avenue of exploration is the potential of mid-regional proadrenomedullin (MR-proADM) as a biomarker in various health conditions, especially in the context of CVD and COVID-19. MR-proADM presents the ability to predict mortality, heart failure, and adverse outcomes in CVD, offering promise for improved risk assessment and treatment strategies. On the other hand, an elevated MR-proADM level is associated with disease severity and cytokine storms in patients with COVID-19, making it a predictive indicator for intensive care unit admissions and mortality rates. Moreover, MR-proADM may have relevance in long COVID, aiding in the risk assessment, triage, and monitoring of individuals at increased risk of developing prolonged cardiac issues. Our review explores the potential of MR-proADM as a predictor of enduring cardiovascular complications following COVID-19 infection.

COVID-19 Complications: Oxidative Stress, Inflammation, and Mitochondrial and Endothelial Dysfunction

SARS-CoV-2 infection, discovered and isolated in Wuhan City, Hubei Province, China, causes acute atypical respiratory symptoms and has led to profound changes in our lives. COVID-19 is characterized by a wide range of complications, which include pulmonary embolism, thromboembolism and arterial clot formation, arrhythmias, cardiomyopathy, multiorgan failure, and more. The disease has caused a worldwide pandemic, and despite various measures such as social distancing, various preventive strategies, and therapeutic approaches, and the creation of vaccines, the novel coronavirus infection (COVID-19) still hides many mysteries for the scientific community. Oxidative stress has been suggested to play an essential role in the pathogenesis of COVID-19, and determining free radical levels in patients with coronavirus infection may provide an insight into disease severity. The generation of abnormal levels of oxidants under a COVID-19-induced cytokine storm causes the irreversible oxidation of a wide range of macromolecules and subsequent damage to cells, tissues, and organs. Clinical studies have shown that oxidative stress initiates endothelial damage, which increases the risk of complications in COVID-19 and post-COVID-19 or long-COVID-19 cases. This review describes the role of oxidative stress and free radicals in the mediation of COVID-19-induced mitochondrial and endothelial dysfunction.

The Relationship between Post-COVID Syndrome and the Burden of Comorbidities Assessed Using the Charlson Comorbidity Index

Introduction: The post-COVID-19 syndrome is a clinical entity characterized by the manifestation of signs and symptoms that develop after the acute phase of COVID-19, which persist for a duration of more than 12 weeks and are not explained by any alternative diagnosis. It has been observed that individuals with pre-existing chronic diseases, including cardiovascular and pulmonary diseases, are at a greater risk of developing post-COVID-19 syndrome. The Charlson Comorbidity Index (CCI) is a useful tool employed to evaluate the burden of comorbidities and predict the prognosis of patients with post-COVID-19 syndrome. The present study aims to assess whether the burden of comorbidities, evaluated using the CCI, correlates with post-COVID-19 syndrome. Materials and Methods: Between 21 April 2020 and 15 May 2023, we enrolled all consecutive outpatients with previous COVID-19 admissions to a post-acute day-hospital service three months after a negative SARS-CoV-2 molecular test. We assessed age, sex, BMI, acute COVID-19 and post-COVID-19 signs, and symptoms and calculated CCI according to its current definition. Post-COVID-19 syndrome was defined as the persistence of at least one sign or symptom lasting more than 12 weeks after COVID-19 resolution and not explained by an alternative diagnosis. The relationship between post-COVID-19 and CCI was explored first with the chi-squared test, then with different binary logistic regression models. We considered significant values of p lower than 0.05. Results: We obtained a cohort of 3636 patients and observed a significant association between the number of post-COVID-19 symptoms and CCI. Patients developing post-COVID-19 were more commonly affected by a greater burden of comorbidities. Patients with at least one CCI point had an increased risk of post-COVID-19 syndrome (OR:2.961; 95%CI: 2.269-3.863; p < 0.0001), which increased further for CCI ≥ 4 (OR:6.062; 95%CI: 3.163-11.618; p < 0.0001). Conclusions: Patients affected by post-COVID-19 show a greater clinical complexity and a larger burden of comorbidities, synthesized by a higher CCI; moreover, a higher CCI seems to correlate with an increasing post-COVID-19 risk, being the presence of ≥1 or ≥4 CCI points associated with a 3-fold and 6-fold increased risk of post-COVID-19 syndrome, respectively.

MICROCIRCULATORY ALTERATIONS IN STABLE CORONARY ARTERY DISEASE PATIENTS WITH CONCOMITANT COVID-19

OBJECTIVE

The aim: To evaluate the alterations in microcirculation of stable coronary artery disease (SCAD) patients with concomitant COVID-19.

PATIENTS AND METHODS

Materials and methods: The cross-sectional study analyzed the data from 80 patients, being subdivided as follows: group 1 (G1) - SCAD without COVID-19 (n=30); group 2 (G2) - SCAD with concomitant COVID-19 (n=25); group 3 (G3) - COVID-19 without SCAD (n=25). The control group included 30 relatively healthy volunteers. The state of microcirculation was assessed by nailfold videocapillaroscopy (NVC) and laser Doppler flowmetry (LDF).

RESULTS

Results: NVC data from G2 revealed the sings of capillary bed remodeling, along with the most pronounced decrease in capillary (arteriolar part of the loop) blood flow velocity (vs. G1 and G3). LDF data from G2 were evident for the alterations in both endothelium-dependent and -independent mechanisms of microvascular flow regulation. The 72 % of G2 constituted the cases of microcirculatory hemodynamic «congestion-stasis» (MHCS) type (characterized by the decreased laser Doppler perfusion index and reduced endothelium-dependent microvascular reactivity [MVR]), and the cases of mixed type with reduced MVR. The pooled hyporeactive profile (of both MHCS type and a mixed type with reduced MVR) demonstrated the higher frequency of G2 patients (40 %), as against 11 % in the pooled alternative hemodynamic group (p<0,001) (included 80 % of cases with preserved MVR).

CONCLUSION

Conclusions: G2 profile demonstrated the predomination of patients, possessing a MHCS type or a mixed type with reduced MVR. The pooled microcirculatory hyporeactive profile was presented with G2 cases to a greater extent, than in the pooled profile with predominantly preserved MVR.