Orthostatic intolerance (OI), including postural orthostatic tachycardia syndrome (PoTS) and orthostatic hypotension (OH), are often reported in long covid, but published studies are small with inconsistent results. We sought to estimate the prevalence of objective OI in patients attending long covid clinics and healthy volunteers and associations with OI symptoms and comorbidities. Participants with a diagnosis of long covid were recruited from eight UK long covid clinics, and healthy volunteers from general population. All undertook standardized National Aeronautics and Space Administration Lean Test (NLT). Participants' history of typical OI symptoms (e.g., dizziness, palpitations) before and during the NLT were recorded. Two hundred seventy-seven long covid patients and 50 frequency-matched healthy volunteers were tested. Healthy volunteers had no history of OI symptoms or symptoms during NLT or PoTS, 10% had asymptomatic OH. One hundred thirty (47%) long covid patients had previous history of OI symptoms and 144 (52%) developed symptoms during the NLT. Forty-one (15%) had an abnormal NLT, 20 (7%) met criteria for PoTS, and 21 (8%) had OH. Of patients with an abnormal NLT, 45% had no prior symptoms of OI. Relaxing the diagnostic thresholds for PoTS from two consecutive abnormal readings to one abnormal reading during the NLT, resulted in 11% of long covid participants (an additional 4%) meeting criteria for PoTS, but not in healthy volunteers. More than half of long covid patients experienced OI symptoms during NLT and more than one in 10 patients met the criteria for either PoTS or OH, half of whom did not report previous typical OI symptoms. We therefore recommend all patients attending long covid clinics are offered an NLT and appropriate management commenced.

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.

### What you need to know Patients with long covid—defined by the National Institute for Health and Care Excellence (NICE) as signs and symptoms that persist for more than four weeks (and especially more than 12 weeks) following acute covid-1912—may present in primary care with symptoms of palpitations (tachycardia) triggered by standing or minimal exertion.3 These may be accompanied by dizziness, breathlessness, chest pain, sweating, bloating, fatigue, and other symptoms which may be caused by a dysfunction of the autonomic nervous system (dysautonomia).45678910111213 Patients can find these symptoms debilitating and they can affect function and mood. Limited evidence, variable diagnostic criteria, uncertainty around cause and pathogenesis, and the absence of licensed medications, have all contributed to making this a difficult condition to diagnose and manage. In this practice pointer, we offer an overview of orthostatic tachycardia following covid-19, including a summary of the key steps for diagnosis and management. Prevalence estimates vary depending on sample and setting, but indicate that about 25% of long covid patients may have dysautonomia14 and 2-14% will develop orthostatic tachycardia (postural orthostatic tachycardia syndrome) six to eight months after infection.341516Box 1 provides more information on these conditions. The assessment and management is summarised in the infographic. Box 1 ### Dysautonomia and postural orthostatic tachycardia syndromes The autonomic nervous system is responsible for the unconscious regulation of many physiological processes, including heart rate, blood pressure, respiration, and digestion. The broad category of "dysautonomia" encompasses several conditions, from the intermittent "faint" (neurocardiogenic syncope) through more pervasive dysregulation (postural … RETURN TO TEXT

Purpose Orthostatic intolerance (OI), including postural orthostatic tachycardia syndrome (PoTS) and orthostatic hypotension (OH), are often reported in long covid, but published studies are small with inconsistent results. We sought to estimate the prevalence of objective OI in patients attending long covid clinics and healthy volunteers and associations with symptoms and comorbidities. Methods Participants were recruited from 8 UK long covid clinics, and healthy volunteers from general population. All undertook standardised National Aeronautics and Space Administration Lean Test (NLT). Participants’ history of typical OI symptoms (e.g. dizziness, palpitations) prior to and during the NLT were recorded. Results 277 long covid patients and 50 frequency-matched healthy volunteers were tested. Healthy volunteers had no history of OI symptoms or PoTS, 10% had asymptomatic OH. 130 (47%) long covid patients had previous history of OI symptoms and 144 (52%) developed symptoms during the NLT. 41 (15%) had an abnormal NLT, 20 (7%) met criteria for PoTS and 21 (8%) had OH. Of patients with an abnormal NLT, 45% had no prior symptoms of OI. Relaxing the diagnostic thresholds for PoTS from two consecutive to one reading, resulted in 11% of long covid participants meeting criteria for PoTS, but not in healthy volunteers. Conclusion More than half of long covid patients experienced OI symptoms during NLT and more than one in ten patients met the criteria for either PoTS or OH, half of whom did not report previous typical OI symptoms. We recommend all patients attending long covid clinics are offered an NLT and appropriate management commenced. Trial registration numbers [NCT05057260][1], ISRCTN15022307 ### Competing Interest Statement All authors have completed the ICMJE uniform disclosure form at www.icmje.org/coi_disclosure.pdf and declare: all authors had financial support from National Institute for Health and Care Research for the submitted work; MS has received grants through his University from UKRI, is Editor-in-Chief of Advances in Rehabilitation Science and Practice, is Editorial Board Member of Frontiers in Pain Research, is President of British Society of Physical and Rehabilitation Medicine; DCG has received grants through his University from British Heart Foundation, NHS England, and NHS National Services Scotland; TG is Independent SAGE member; there are no other relationships or activities that could appear to have influenced the submitted work; JS has received research grants from the Wellcome Trust, Public Health Scotland and, Office of the Chief Scientific Adviser Scotland. ### Funding Statement This work is independent research funded by the National Institute for Health and Care Research (NIHR) (Long Covid grant, Ref: COV-LT2-0016). The views expressed in this publication are those of the authors and not necessarily those of NIHR or The Department of Health and Social Care. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: Ethics approval was granted by Yorkshire and The Humber, Bradford Leeds Research Ethics Committee (REC; ref: 21/YH/0276) and subsequent amendments. I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes All data produced in the present study are available upon reasonable request to the authors. [1]: /lookup/external-ref?link_type=CLINTRIALGOV&access_num=NCT05057260&atom=%2Fmedrxiv%2Fearly%2F2023%2F12%2F18%2F2023.12.18.23299958.atom