Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has spread worldwide, with > 640 million people infected [1]. Recently, attention has been focused on acute coronavirus disease (COVID-19) symptoms and the disease’s sequelae, known as long COVID. The Centers for Disease Control and Prevention (CDC) defines long COVID as the onset of symptoms after 4 weeks of SARS-CoV-2 infection [2]. The World Health Organization (WHO) defines it as follows: (i) usually 3 months from the onset of COVID-19, (ii) with symptoms that last for ≥ 2 months, and (iii) cannot be explained by an alternative diagnosis. Common symptoms include fatigue, shortness of breath, and cognitive dysfunction, which generally impact daily functioning. New-onset symptoms of long COVID may occur following initial recovery from acute COVID-19, or symptoms may persist from the initial illness. In addition, the symptoms may fluctuate or relapse over time [3].
The incidence of long COVID was reported to be 70% in hospitalized patients in China [4]. However, as the epidemic strains changed to Delta and Omicron, the incidence was estimated as 10.8% and 4.5%, respectively [5]. Furthermore, symptoms were reported to remain at 10–30% after 1 year [6]. More than 50 symptoms of COVID-19 sequelae have been reported, with the most common manifestations being fatigue, headache, attention disorder, hair loss, and dyspnea. Other symptoms include post-activity polypnea, sweating abnormalities, nausea or vomiting, chest pains or discomfort, increased resting heart rate (HR), sleep disorders, flushing, and dizziness [7]. These symptoms are similar to those observed in patients with autonomic dysfunction [8]. Hence, attention was drawn to postural orthostatic tachycardia syndrome (POTS) as a complication of long COVID [9].
POTS incidence ranges from 0.2–1% in the US population, based largely on clinical experience, suggesting that approximately 1–3 million individuals are affected in this population [10]. Orthostatic symptoms include lightheadedness, visual blurring, tunnel vision, palpitations, tremulousness, and weakness (especially in the legs). Other symptoms include fatigue, exercise intolerance, hyperventilation, shortness of breath, anxiety, chest pain, nausea, acral coldness or pain, concentration difficulties, and headache [11].
Factors contributing to the development of POTS after COVID-19 are hypovolemia, neurotropism, inflammation, and autoimmunity [12]. Long COVID complicated by POTS was first reported by Miglis et al. [13], and several reports have been published [14–16]. Blitshteyn et al. reported a case series of 20 patients with long COVID complicated by autonomic neuropathy, 15 of whom had POTS. Follow-up of these patients for 6–8 months showed that only three patients could return fully to work [17].
Our facility started to observe patients with long COVID in January 2021. As a university hospital, we treat patients through the Department of General Medicine and multidisciplinary cooperation, including specialists according to symptoms, nurses to care for their mental problems, and financial support from medical social workers. Hence, orthostatic examinations were performed for all patients who complained of fatigue. If patients were diagnosed with POTS, lifestyle guidance, such as salt and fluid intake, was provided, and beta-blockers were prescribed as standard treatment [18, 19]. In some cases, an otolaryngologist, psychiatrists, and social workers were consulted to treat autonomic dysfunction using epipharyngeal abrasion therapy (EAT), treat mental problems, and provide financial support, respectively. There have been reports of POTS diagnosed as a COVID-19 complication, as described above. However, we could not find any report describing the detailed treatment course of an individual patient. Therefore, this study reports the treatment course of long COVID with POTS. Given that β blockers are not always effective in POTS treatment, this study also aimed to examine the factors that influenced the efficacy of β blockers.