Use of Cardiopulmonary Exercise Testing to Evaluate Long COVID-19 Symptoms in Adults: A Systematic Review and Meta-analysis

Abstract

Importance: Reduced exercise capacity is commonly reported among individuals with COVID-19 symptoms more than 3 months after SARS-CoV-2 infection (long COVID-19 [LC]). Cardiopulmonary exercise testing (CPET) is the criterion standard to measure exercise capacity and identify patterns of exertional intolerance.

Objectives: To estimate the difference in exercise capacity among individuals with and without LC symptoms and characterize physiological patterns of limitations to elucidate possible mechanisms of LC.

Data sources: A search of PubMed, EMBASE, Web of Science, preprint servers, conference abstracts, and cited references was performed on December 20, 2021, and again on May 24, 2022. A preprint search of medrxiv.org, biorxiv.org, and researchsquare.com was performed on June 9, 2022.

Study selection: Studies of adults with SARS-CoV-2 infection more than 3 months earlier that included CPET-measured peak oxygen consumption (V̇o2) were screened independently by 2 blinded reviewers; 72 (2%) were selected for full-text review, and 35 (1%) met the inclusion criteria. An additional 3 studies were identified from preprint servers.

Data extraction and synthesis: Data extraction was performed by 2 independent reviewers according to the PRISMA reporting guideline. Data were pooled using random-effects models.

Main outcomes and measures: Difference in peak V̇o2 (in mL/kg/min) among individuals with and without persistent COVID-19 symptoms more than 3 months after SARS-CoV-2 infection.

Results: A total of 38 studies were identified that performed CPET on 2160 individuals 3 to 18 months after SARS-CoV-2 infection, including 1228 with symptoms consistent with LC. Most studies were case series of individuals with LC or cross-sectional assessments within posthospitalization cohorts. Based on a meta-analysis of 9 studies including 464 individuals with LC symptoms and 359 without symptoms, the mean peak V̇o2 was -4.9 (95% CI, -6.4 to -3.4) mL/kg/min among those with symptoms with a low degree of certainty. Deconditioning and peripheral limitations (abnormal oxygen extraction) were common, but dysfunctional breathing and chronotropic incompetence were also described. The existing literature was limited by small sample sizes, selection bias, confounding, and varying symptom definitions and CPET interpretations, resulting in high risk of bias and heterogeneity.

Conclusions and relevance: The findings of this systematic review and meta-analysis study suggest that exercise capacity was reduced more than 3 months after SARS-CoV-2 infection among individuals with symptoms consistent with LC compared with individuals without LC symptoms, with low confidence. Potential mechanisms for exertional intolerance other than deconditioning include altered autonomic function (eg, chronotropic incompetence, dysfunctional breathing), endothelial dysfunction, and muscular or mitochondrial pathology.

Source: Durstenfeld MS, Sun K, Tahir P, Peluso MJ, Deeks SG, Aras MA, Grandis DJ, Long CS, Beatty A, Hsue PY. Use of Cardiopulmonary Exercise Testing to Evaluate Long COVID-19 Symptoms in Adults: A Systematic Review and Meta-analysis. JAMA Netw Open. 2022 Oct 3;5(10):e2236057. doi: 10.1001/jamanetworkopen.2022.36057. PMID: 36223120. https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2797203 (Full text)

Long-Haul COVID Patients: Prevalence of POTS Are Reduced but Cerebral Blood Flow Abnormalities Remain Abnormal with Longer Disease Duration

Abstract:

Background: Postural orthostatic tachycardia syndrome (POTS) has been described early after the onset of the COVID-19 infection, but also orthostatic hypotension (OH). In the present study, we hypothesized that orthostatic intolerance decreases over time.
Methods: In 29 long-haul COVID-19 (LHC) patients, a tilt test was performed, including measurements of cerebral blood flow (CBF) by extracranial Doppler. The time interval between the onset of infection and the tilt test varied between 3 and 28 months.
Results: In the first 12 months after the infection, 71% of the LHC patients showed POTS and after 24 months none of them. In the first 12 months, 29% of patients had a normal heart rate and blood pressure response (normHRBP) and after 24 months 75% (distribution of POTS, OH, and a normHRBP over time: p < 0.0001). Linear regression showed that, over time, there was a decrease in the abnormal CBF during the tilt (p = 0.024) but remained abnormal.
Conclusion: In LHC patients, hemodynamic abnormalities of a tilt test change over time. Patients studied early after the onset of the disease mainly exhibit POTS, but patients studied later in the time course mainly show a normHRBP or OH. In addition, the abnormal CBF reduction improves over time, but CBF remains abnormal.
Source: Campen CMCv, Visser FC. Long-Haul COVID Patients: Prevalence of POTS Are Reduced but Cerebral Blood Flow Abnormalities Remain Abnormal with Longer Disease Duration. Healthcare. 2022; 10(10):2105. https://doi.org/10.3390/healthcare10102105 https://www.mdpi.com/2227-9032/10/10/2105/htm (Full text)

Orthostatic Intolerance in Long-Haul COVID after SARS-CoV-2: A Case-Control Comparison with Post-EBV and Insidious-Onset Myalgic Encephalomyelitis/Chronic Fatigue Syndrome Patients

Background: As complaints of long-haul COVID patients are similar to those of ME/CFS patients and as orthostatic intolerance (OI) plays an important role in the COVID infection symptomatology, we compared 14 long-haul COVID patients with 14 ME/CFS patients with a post-viral Ebstein-Barr (EBV) onset and 14 ME/CFS patients with an insidious onset of the disease.
Methods: In all patients, OI analysis by history taking and OI assessed during a tilt test, as well as cerebral blood flow measurements by extracranial Doppler, and cardiac index measurements by suprasternal Doppler during the tilt test were obtained in all patients.
Results: Except for disease duration no differences were found in clinical characteristics. The prevalence of POTS was higher in the long-haul patients (100%) than in post-EBV (43%) and in insidious-onset (50%) patients (p = 0.0002). No differences between the three groups were present in the prevalence of OI, heart rate and blood pressure changes, changes in cerebral blood flow or in cardiac index during the tilt test.
Conclusion: OI symptomatology and objective abnormalities of OI (abnormal cerebral blood flow and cardiac index reduction during tilt testing) are comparable to those in ME/CFS patients. It indicates that long-haul COVID is essentially the same disease as ME/CFS.
Source: van Campen CMC, Visser FC. Orthostatic Intolerance in Long-Haul COVID after SARS-CoV-2: A Case-Control Comparison with Post-EBV and Insidious-Onset Myalgic Encephalomyelitis/Chronic Fatigue Syndrome Patients. Healthcare. 2022; 10(10):2058. https://doi.org/10.3390/healthcare10102058 (Full text)

Antioxidants and Long Covid

Abstract:

Long Covid has many symptoms that overlap with ME(myalgic encephalomyelitis)/CFS(chronic fatigue syndrome), FM(fibromyalgia), EBV(Epstein-Barr virus), CMV(cytomegalovirus), CIRS (chronic inflammatory response syndrome), MCAS(mast cell activation syndrome), POTS(postural orthostatic tachycardia syndrome), and post viral fatigue syndrome. They all portend a “long haul” with an antioxidant shortfall and elevated Ca:Mg. Oxidative stress is the root cause.

Linkage between TGF(transforming growth factor)-β, IFN(interferon)-γ, the RAS(renin angiotensin system), and the KKS(kallikrein kinin system) is discussed. Technical explanations for the renin aldosterone paradox in POTS, the betrayal of TGF-β, and the commonality of markers for the Warburg effect are offered. The etiology of the common Long Covid symptoms of post exertional malaise, fatigue, and brain fog as well as anosmia, hair loss, and GI symptoms is technically discussed. Ca:Mg is critical to the glutamate/GABA balance. The role of GABA and butyrates from the “good” intestinal bacteria in the gut-brain axis and its correlation with chronic fatigue diseases are explored.

The crosstalk between the ENS(enteric nervous system) and the ANS(autonomic nervous system) and the role of the vagus in both are emphasized. HRV(heart rate variability), the fifth vital sign, points to an expanded gut-brain-heart/lung axis. A suggested approach to all of these – Long Covid, chronic fatigue diseases, post viral fatigue syndrome, and general health – is presented.

Source: Chambers, P. Antioxidants and Long Covid. Preprints 2022, 2022100195 (doi: 10.20944/preprints202210.0195.v1).  https://www.preprints.org/manuscript/202210.0195/v1 (Full text available as PDF file)

Acute COVID-19 Syndrome Predicts Severe Long COVID-19: An Observational Study

Abstract:

Introduction Tissue damage, chronic dysfunction, and symptoms that last more than 12 weeks are hallmarks of long-term chronic opportunistic viral infection (COVID-19), and the disease may have a permanent, relapsing/remitting, or gradually improving course. This study aimed to determine the risk factors of severe long COVID-19.

Methods In October 2021, primary care clinics enrolled consenting 18- to 89-year-olds to complete an online questionnaire on self-diagnosis, clinician diagnosis, testing, symptom presence, and duration of COVID-19. Long COVID-19 was identified if symptoms were beyond 12 weeks. Patients with long-lasting COVID-19 symptoms were assessed using multivariable regression to identify potential predictors of severe long COVID-19.

Results Of the 220 respondents, 108 (49%) patients were self- or clinician-diagnosed with COVID-19 or had a confirmed positive laboratory test result. Patients aged >45 years and with at least 15 COVID-19 symptoms were 5.55 and 6.02 times, respectively, more likely to acquire severe long COVID-19. Most patients with severe and moderate post-acute COVID-19 syndrome had no relevant comorbidities (p=0.0402; odds ratio [OR]=0.4; 95% confidence interval [CI]=0.18-0.98). Obesity was a significant predictor (p=0.0307; OR=6.2; 95% CI=1.1-33.2).

Conclusion The simultaneous presence of 15 or more COVID-19 symptoms, age >45 years, and obesity were related to a higher probability of severe long COVID-19.

Source: Menezes AS Jr, Botelho SM, Santos LR, Rezende AL. Acute COVID-19 Syndrome Predicts Severe Long COVID-19: An Observational Study. Cureus. 2022 Oct 2;14(10):e29826. doi: 10.7759/cureus.29826. PMID: 36204261; PMCID: PMC9527039.  https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9527039/ (Full text)

Pathophysiology of Post-COVID syndromes: a new perspective

Abstract:

Most COVID-19 patients recovered with low mortality; however, some patients experienced long-term symptoms described as “long-COVID” or “Post-COVID syndrome” (PCS). Patients may have persisting symptoms for weeks after acute SARS-CoV-2 infection, including dyspnea, fatigue, myalgia, insomnia, cognitive and olfactory disorders. These symptoms may last for months in some patients.

PCS may progress in association with the development of mast cell activation syndrome (MCAS), which is a distinct kind of mast cell activation disorder, characterized by hyper-activation of mast cells with inappropriate and excessive release of chemical mediators. COVID-19 survivors, mainly women, and patients with persistent severe fatigue for 10 weeks after recovery with a history of neuropsychiatric disorders are more prone to develop PCS. High D-dimer levels and blood urea nitrogen were observed to be risk factors associated with pulmonary dysfunction in COVID-19 survivors 3 months post-hospital discharge with the development of PCS. PCS has systemic manifestations that resolve with time with no further complications. However, the final outcomes of PCS are chiefly unknown.

Persistence of inflammatory reactions, autoimmune mimicry, and reactivation of pathogens together with host microbiome alterations may contribute to the development of PCS. The deregulated release of inflammatory mediators in MCAS produces extraordinary symptoms in patients with PCS. The development of MCAS during the course of SARS-CoV-2 infection is correlated to COVID-19 severity and the development of PCS. Therefore, MCAS is treated by antihistamines, inhibition of synthesis of mediators, inhibition of mediator release, and inhibition of degranulation of mast cells.

Source: Batiha, G.ES., Al-kuraishy, H.M., Al-Gareeb, A.I. et al. Pathophysiology of Post-COVID syndromes: a new perspective. Virol J 19, 158 (2022). https://doi.org/10.1186/s12985-022-01891-2  https://virologyj.biomedcentral.com/articles/10.1186/s12985-022-01891-2 (Full text)

Sleep symptoms are essential features of long-COVID – Comparing healthy controls with COVID-19 cases of different severity in the international COVID sleep study (ICOSS-II)

Abstract:

Many people report suffering from post-acute sequelae of COVID-19 or “long-COVID”, but there are still open questions on what actually constitutes long-COVID and how prevalent it is. The current definition of post-acute sequelae of COVID-19 is based on voting using the Delphi-method by the WHO post-COVID-19 working group. It emphasizes long-lasting fatigue, shortness of breath and cognitive dysfunction as the core symptoms of post-acute sequelae of COVID-19.

In this international survey study consisting of 13,628 subjects aged 18-99 years from 16 countries of Asia, Europe, North America and South America (May-Dec 2021), we show that post-acute sequelae of COVID-19 symptoms were more prevalent amongst the more severe COVID-19 cases, i.e. those requiring hospitalisation for COVID-19. We also found that long-lasting sleep symptoms are at the core of post-acute sequelae of COVID-19 and associate with the COVID-19 severity when COVID-19 cases are compared with COVID-negative cases.

Specifically, fatigue (61.3%), insomnia symptoms (49.6%) and excessive daytime sleepiness (35.8%) were highly prevalent amongst respondents reporting long-lasting symptoms after hospitalisation for COVID-19. Understanding the importance of sleep-related symptoms in post-acute sequelae of COVID-19 has a clinical relevance when diagnosing and treating long-COVID.

Source: Merikanto I, Dauvilliers Y, Chung F, Wing YK, de Gennaro L, Holzinger B, Bjorvatn B, Morin CM, Penzel T, Benedict C, Koscec Bjelajac A, Chan NY, Espie CA, Hrubos-Strøm H, Inoue Y, Korman M, Landtblom AM, Léger D, Matsui K, Mota-Rolim S, Nadorff MR, Plazzi G, Reis C, Yordanova J, Partinen M. Sleep symptoms are essential features of long-COVID – Comparing healthy controls with COVID-19 cases of different severity in the international COVID sleep study (ICOSS-II). J Sleep Res. 2022 Oct 8:e13754. doi: 10.1111/jsr.13754. Epub ahead of print. PMID: 36208038. https://onlinelibrary.wiley.com/doi/10.1111/jsr.13754 (Full text)

Symptomatology and microbiology of the gastrointestinal tract in post-COVID conditions

Abstract:

Post-COVID conditions, also known as post-acute sequelae of SARS-CoV-2 (PASC), refer to the persistence of symptoms in COVID-19 long-haulers. Various manifestations of post-COVID conditions are general symptoms and/or manifestations of damage in multiple organs. Besides, SARS-CoV-2 can involve the gastrointestinal tract, resulting in sequelae such as diarrhea, abdominal pain, nausea, anorexia, vomiting, constipation, abdominal distension, acid reflux, and/or gastrointestinal bleeding.
Previous investigations point to SARS-CoV-2 entry into enterocytes enhances by the angiotensin-converting enzyme 2 (ACE2) receptors. Interestingly, ACE2 receptors are abundantly expressed in the gut, implying infection with SARS-CoV-2 might occur through this route as well as in the respiratory tract. According to mounting evidence, SARS-CoV-2 RNA has been identified in fecal specimens of patients with COVID-19 during and beyond the acute phase.
In addition, studies have shown gut microbiome composition is altered in patients with PASC, hence, another putative mechanism linked to gastrointestinal symptoms is gut dysbiosis. The presence of the gut-lung axis in COVID-19 might have major implications for disease pathogenesis and treatment.
This review discussed the prevalence of gastrointestinal symptoms and pathophysiology underlying possible infection of the gut in patients with PASC. Also, SARS-COV-2 induced NLRP3 inflammasome-dependent inflammatory pathways are briefly addressed.
Source: Norouzi Masir M, Shirvaliloo M. Symptomatology and microbiology of the gastrointestinal tract in post-COVID conditions. JGH Open : an Open Access Journal of Gastroenterology and Hepatology. 2022 Aug. DOI: 10.1002/jgh3.12811. PMID: 36247234; PMCID: PMC9538198. https://europepmc.org/article/pmc/pmc9538198 (Full text)

Endothelial dysfunction in COVID-19: an overview of evidence, biomarkers, mechanisms and potential therapies

Abstract:

The fight against coronavirus disease 2019 (COVID-19) caused by SARS-CoV-2 infection is still raging. However, the pathophysiology of acute and post-acute manifestations of COVID-19 (long COVID-19) is understudied. Endothelial cells are sentinels lining the innermost layer of blood vessel that gatekeep micro- and macro-vascular health by sensing pathogen/danger signals and secreting vasoactive molecules. SARS-CoV-2 infection primarily affects the pulmonary system, but accumulating evidence suggests that it also affects the pan-vasculature in the extrapulmonary systems by directly (via virus infection) or indirectly (via cytokine storm), causing endothelial dysfunction (endotheliitis, endothelialitis and endotheliopathy) and multi-organ injury.

Mounting evidence suggests that SARS-CoV-2 infection leads to multiple instances of endothelial dysfunction, including reduced nitric oxide (NO) bioavailability, oxidative stress, endothelial injury, glycocalyx/barrier disruption, hyperpermeability, inflammation/leukocyte adhesion, senescence, endothelial-to-mesenchymal transition (EndoMT), hypercoagulability, thrombosis and many others. Thus, COVID-19 is deemed as a (micro)vascular and endothelial disease. Of translational relevance, several candidate drugs which are endothelial protective have been shown to improve clinical manifestations of COVID-19 patients.

The purpose of this review is to provide a latest summary of biomarkers associated with endothelial cell activation in COVID-19 and offer mechanistic insights into the molecular basis of endothelial activation/dysfunction in macro- and micro-vasculature of COVID-19 patients. We envisage further development of cellular models and suitable animal models mimicking endothelial dysfunction aspect of COVID-19 being able to accelerate the discovery of new drugs targeting endothelial dysfunction in pan-vasculature from COVID-19 patients.

Source: Xu, Sw., Ilyas, I. & Weng, Jp. Endothelial dysfunction in COVID-19: an overview of evidence, biomarkers, mechanisms and potential therapies. Acta Pharmacol Sin (2022). https://doi.org/10.1038/s41401-022-00998-0 https://www.nature.com/articles/s41401-022-00998-0 (Full text)

New‑onset neuropsychiatric sequelae and ‘long‑COVID’ syndrome (Review)

Abstract:

The ongoing coronavirus disease 2019 (COVID‑19) pandemic has had a widespread impact on individuals’ mental health through indirect psychological and social mechanisms, related to factors such as fear of infection or death, social isolation, lack of social support and financial instability.
The severe acute respiratory syndrome coronavirus 2 (SARS‑CoV‑2) infection has also been associated with the development or recurrence of neuropsychiatric symptoms, both during the acute phase, as well as during the post‑acute ‘long‑COVID’ phase. In addition to the COVID‑19 survivors with a mental health history that are at a high risk of experiencing a range of neuropsychiatric symptoms following resolution of acute COVID‑19, there is accumulating evidence that a diagnosis of COVID‑19 may also be associated with new‑onset neuropsychiatric morbidity among survivors without pre‑existing mental health disorders.
In particular, studies investigating the incidence of post‑acute neuropsychiatric sequelae, based mostly on retrospective cohort study designs and data from national health registries, have reported the development of new‑onset manifestations, including depression, anxiety, psychotic symptoms, sleep disturbances and fatigue. Nevertheless, when COVID‑19 survivors were compared with SARS‑CoV‑2‑negative controls and especially survivors of other disorders (such as influenza), the findings regarding the risk of incident neuropsychiatric manifestations varied among studies.
While there is evidence of an association between SARS‑CoV‑2 infection and the subsequent occurrence of new‑onset neuropsychiatric symptoms, especially among patients with increased disease severity, further research using methodological approaches less susceptible to confounding bias is required to establish causal relationships.
Source: Efstathiou, V., Stefanou, M., Demetriou, M., Siafakas, N., Katsantoni, E., Makris, M., Tsivgoulis, G., Zoumpourlis, V., Kympouropoulos, S. P., Tsoporis, J. N., Spandidos, D. A., Ferentinos, P., Smyrnis, N., Rizos, E.”New‑onset neuropsychiatric sequelae and ‘long‑COVID’ syndrome (Review)”. Experimental and Therapeutic Medicine 24.5 (2022): 705. https://www.spandidos-publications.com/10.3892/etm.2022.11641 (Full text available as PDF file)