Clinical presentation and management strategies of cardiovascular autonomic dysfunction following a COVID-19 infection - A systematic review

Cardiovascular autonomic dysfunction in post-COVID-19 syndrome: a major health-care burden

Cardiovascular autonomic dysfunction (CVAD) is a malfunction of the cardiovascular system caused by deranged autonomic control of circulatory homeostasis. CVAD is an important component of post-COVID-19 syndrome, also termed long COVID, and might affect one-third of highly symptomatic patients with COVID-19. The effects of CVAD can be seen at both the whole-body level, with impairment of heart rate and blood pressure control, and in specific body regions, typically manifesting as microvascular dysfunction. Many severely affected patients with long COVID meet the diagnostic criteria for two common presentations of CVAD: postural orthostatic tachycardia syndrome and inappropriate sinus tachycardia. CVAD can also manifest as disorders associated with hypotension, such as orthostatic or postprandial hypotension, and recurrent reflex syncope. Advances in research, accelerated by the COVID-19 pandemic, have identified new potential pathophysiological mechanisms, diagnostic methods and therapeutic targets in CVAD. For clinicians who daily see patients with CVAD, knowledge of its symptomatology, detection and appropriate management is more important than ever. In this Review, we define CVAD and its major forms that are encountered in post-COVID-19 syndrome, describe possible CVAD aetiologies, and discuss how CVAD, as a component of post-COVID-19 syndrome, can be diagnosed and managed. Moreover, we outline directions for future research to discover more efficient ways to cope with this prevalent and long-lasting condition.

A Comprehensive Review of the Global Epidemiology, Clinical Management, Socio-Economic Impacts, and National Responses to Long COVID with Future Research Directions

Background: Long COVID, characterized by a persistent symptom spectrum following SARS-CoV-2 infection, poses significant health, social, and economic challenges. This review aims to consolidate knowledge on its epidemiology, clinical features, and underlying mechanisms to guide global responses; Methods: We conducted a literature review, analyzing peer-reviewed articles and reports to gather comprehensive data on long COVID's epidemiology, symptomatology, and management approaches; Results: Our analysis revealed a wide array of long COVID symptoms and risk factors, with notable demographic variability. The current understanding of its pathophysiology suggests a multifactorial origin yet remains partially understood. Emerging diagnostic criteria and potential therapeutic strategies were identified, highlighting advancements in long COVID management; Conclusions: This review highlights the multifaceted nature of long COVID, revealing a broad spectrum of symptoms, diverse risk factors, and the complex interplay of physiological mechanisms underpinning the condition. Long COVID symptoms and disorders will continue to weigh on healthcare systems in years to come. Addressing long COVID requires a holistic management strategy that integrates clinical care, social support, and policy initiatives. The findings underscore the need for increased international cooperation in research and health planning to address the complex challenges of long COVID. There is a call for continued refinement of diagnostic and treatment modalities, emphasizing a multidisciplinary approach to manage the ongoing and evolving impacts of the condition.

Lessons learned in implementing a multidisciplinary long COVID clinic

The diagnosis and treatment of long COVID patients is challenging. Our aim is to share lessons learned using a multidisciplinary approach within the Veterans Affairs system. Our long COVID clinic is based in primary care but has imbedded rehabilitations specialists, nutrition. whole health and different specialists within internal medicine. We conduct an extensive work-up to evaluate the presence of end-organ damage, ongoing inflammation and dysautonomia. Our treatments are based on the prior experience that the VA system has on chronic fatigue syndrome and gulf war illness.

Repeated Syncope Following COVID-19 Infection

A 74-year-old woman presented to our hospital with syncope after a coronavirus disease 2019 (COVID-19) infection. Upon admission, she passed out, and an 8 second sinus arrest was detected during telemetry monitoring. During the next syncope episode, telemetry monitoring showed that her heart rate decreased from 80 to 36 bpm, accompanied by a 2.4 second pause. A permanent pacemaker was implanted; however, the patient still experienced syncope. The head-up tilt test revealed a vasodepressor reflex syncope. The need for permanent pacemakers in patients with syncope following COVID-19 therefore remains controversial.

The European Academy of Neurology NeuroCOVID-19 Task Force: A lesson for the future

BACKGROUND

The COVID-19 pandemic has made its mark on world history forever causing millions of deaths, and straining health systems, economies, and societies worldwide. The European Academy of Neurology (EAN) reacted promptly. A special NeuroCOVID-19 Task Force was set up at the beginning of the pandemic to promote knowledge, research, international collaborations, and raise awareness about the prevention and treatment of COVID-19-related neurological issues.

METHODS

Activities carried out during and after the pandemic by the EAN NeuroCOVID-19 Task Force are described. The main aim was to review all these initiatives in detail as an overarching lesson from the past to improve the present and be better prepared in case of future pandemics.

RESULTS

During the pandemic, the Task Force was engaged in several initiatives: the creation of the EAN NEuro-covid ReGistrY (ENERGY); the launch of several surveys (neurological manifestations of COVID-19 infection; the pandemic's impact on patients with chronic neurological diseases; the pandemic's impact of restrictions for clinical practice, curricular training, and health economics); the publication of position papers regarding the management of patients with neurological diseases during the pandemic, and vaccination hesitancy among people with chronic neurological disorders; and the creation of a dedicated "COVID-19 Breaking News" section in EANpages.

CONCLUSIONS

The EAN NeuroCOVID-19 Task Force was immediately engaged in various activities to participate in the fight against COVID-19. The Task Force's concerted strategy may serve as a foundation for upcoming global neurological emergencies.

The Role of Heparin in Postural Orthostatic Tachycardia Syndrome and Other Post-Acute Sequelae of COVID-19

The therapeutic management and short-term consequences of the coronavirus disease 2019 (COVID-19) are well known. However, COVID-19 post-acute sequelae are less known and represent a public health problem worldwide. Patients with COVID-19 who present post-acute sequelae may display immune dysregulation, a procoagulant state, and persistent microvascular endotheliopathy that could trigger microvascular thrombosis. These elements have also been implicated in the physiopathology of postural orthostatic tachycardia syndrome, a frequent sequela in post-COVID-19 patients. These mechanisms, directly associated with post-acute sequelae, might determine the thrombotic consequences of COVID-19 and the need for early anticoagulation therapy. In this context, heparin has several potential benefits, including immunomodulatory, anticoagulant, antiviral, pro-endothelial, and vascular effects, that could be helpful in the treatment of COVID-19 post-acute sequelae. In this article, we review the evidence surrounding the post-acute sequelae of COVID-19 and the potential benefits of the use of heparin, with a special focus on the treatment of postural orthostatic tachycardia syndrome.

Long-COVID-19 autonomic dysfunction: An integrated view in the framework of inflammaging

The recently identified syndrome known as Long COVID (LC) is characterized by a constellation of debilitating conditions that impair both physical and cognitive functions, thus reducing the quality of life and increasing the risk of developing the most common age-related diseases. These conditions are linked to the presence of symptoms of autonomic dysfunction, in association with low cortisol levels, suggestive of reduced hypothalamic-pituitary-adrenal (HPA) axis activity, and with increased pro-inflammatory condition. Alterations of dopamine and serotonin neurotransmitter levels were also recently observed in LC. Interestingly, at least some of the proposed mechanisms of LC development overlap with mechanisms of Autonomic Nervous System (ANS) imbalance, previously detailed in the framework of the aging process. ANS imbalance is characterized by a proinflammatory sympathetic overdrive, and a concomitant decreased anti-inflammatory vagal parasympathetic activity, associated with reduced anti-inflammatory effects of the HPA axis and cholinergic anti-inflammatory pathway (CAP). These neuro-immune-endocrine system imbalanced activities fuel the vicious circle of chronic inflammation, i.e. inflammaging. Here, we refine our original hypothesis that ANS dysfunction fuels inflammaging and propose that biomarkers of ANS imbalance could also be considered biomarkers of inflammaging, recognized as the main risk factor for developing age-related diseases and the sequelae of viral infections, i.e. LC.

Autoimmune Autonomic Neuropathy: From Pathogenesis to Diagnosis

Autoimmune autonomic ganglionopathy (AAG) is a disease of autonomic failure caused by ganglionic acetylcholine receptor (gAChR) autoantibodies. Although the detection of autoantibodies is important for distinguishing the disease from other neuropathies that present with autonomic dysfunction, other factors are important for accurate diagnosis. Here, we provide a comprehensive review of the clinical features of AAG, highlighting differences in clinical course, clinical presentation, and laboratory findings from other neuropathies presenting with autonomic symptoms. The first step in diagnosing AAG is careful history taking, which should reveal whether the mode of onset is acute or chronic, followed by an examination of the time course of disease progression, including the presentation of autonomic and extra-autonomic symptoms. AAG is a neuropathy that should be differentiated from other neuropathies when the patient presents with autonomic dysfunction. Immune-mediated neuropathies, such as acute autonomic sensory neuropathy, are sometimes difficult to differentiate, and therefore, differences in clinical and laboratory findings should be well understood. Other non-neuropathic conditions, such as postural orthostatic tachycardia syndrome, chronic fatigue syndrome, and long COVID, also present with symptoms similar to those of AAG. Although often challenging, efforts should be made to differentiate among the disease candidates.

Treatment of long COVID complicated by postural orthostatic tachycardia syndrome-Case series research

Background

Coronavirus disease 2019 (COVID-19) sequelae, also known as long COVID, can present with various symptoms. Among these symptoms, autonomic dysregulation, particularly postural orthostatic tachycardia syndrome (POTS), should be evaluated. However, previous studies on the treatment of POTS complicated by COVID-19 are lacking. Therefore, this study aimed to investigate the treatment course of long COVID complicated by POTS.

Methods

The medical records of patients who complained of fatigue and met the criteria for POTS diagnosis were reviewed. We evaluated the treatment days, methods and changes in fatigue score, changes in heart rate on the Schellong test, and social situation at the first and last visits.

Results

Thirty-two patients with long COVID complicated by POTS were followed up (16 males; median age: 28 years). The follow-up period was 159 days, and the interval between COVID-19 onset and initial hospital attendance was 97 days. Some patients responded to β-blocker therapy. Many patients had psychiatric symptoms that required psychiatric intervention and selective serotonin reuptake inhibitor prescription. Changes in heart rate, performance status, and employment/education status improved from the first to the last visit. These outcomes were believed to be because of the effects of various treatment interventions and spontaneous improvements.

Conclusions

Our study suggests that the condition of 94% of patients with POTS complicated by long COVID will improve within 159 days. Therefore, POTS evaluation should be considered when patients with long COVID complain of fatigue, and attention should be paid to psychological symptoms and the social context.

Autonomic Manifestations of Long-COVID Syndrome

PURPOSE OF REVIEW

Long-COVID is a novel condition emerging from the COVID-19 pandemic. Long-COVID is characterized by symptoms commonly seen in autonomic disorders including fatigue, brain fog, light-headedness, and palpitations. This article will critically evaluate recent findings and studies on Long-COVID and its physiological autonomic manifestations.

RECENT FINDINGS

Studies have reported on the prevalence of different symptoms and autonomic disorders in Long-COVID cohorts. Autonomic nervous system function, including both the parasympathetic and sympathetic limbs, has been studied using different testing techniques in Long-COVID patients. While numerous mechanisms may contribute to Long-COVID autonomic pathophysiology, it is currently unclear which ones lead to a Long-COVID presentation. To date, studies have not tested treatment options for autonomic disorders in Long-COVID patients. Long-COVID is associated with autonomic abnormalities. There is a high prevalence of clinical autonomic disorders among Long-COVID patients, with limited knowledge of the underlying mechanisms and the effectiveness of treatment options.

Pooled rates and demographics of POTS following SARS-CoV-2 infection versus COVID-19 vaccination: Systematic review and meta-analysis

PURPOSE

To address recent concerns of postural orthostatic tachycardia syndrome (POTS) occurring after severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and coronavirus disease 2019 (COVID-19) vaccination.

METHODS

We searched PubMed, Web of Science, and Scopus as of 1st June 2023. We performed a systematic review and meta-analysis of pooled POTS rate in SARS-CoV-2-infected and COVID-19-vaccinated groups from epidemiological studies, followed by subgroup analyses by characteristic. Meta-analysis of risk ratio was conducted to compare POTS rate in infected versus uninfected groups. Meta-analysis of demographics was also performed to compare cases of post-infection and post-vaccination POTS from case reports and series.

RESULTS

We estimated the pooled POTS rate of 107.75 (95 % CI: 9.73 to 273.52) and 3.94 (95 % CI: 0 to 16.39) cases per 10,000 (i.e., 1.08 % and 0.039 %) in infected and vaccinated individuals based on 5 and 2 studies, respectively. Meta-regression revealed age as a significant variable influencing 86.2 % variance of the pooled POTS rate in infected population (P < 0.05). Moreover, POTS was 2.12-fold more likely to occur in infected than uninfected individuals (RR = 2.12, 95 % CI: 1.71 to 2.62, P < 0.001). Meta-analyzed demographics for cases of post-infection (n = 43) and post-vaccination (n = 17) POTS found no significant differences in several variables between groups, except that the time from exposure to symptom onset was shorter for cases of post-vaccination POTS (P < 0.05).

CONCLUSION

Although evidence is limited for post-vaccination POTS, our study showed that POTS occur more frequently following SARS-CoV-2 infection than COVID-19 vaccination.

EFAS/EAN survey on the influence of the COVID-19 pandemic on European clinical autonomic education and research

PURPOSE

To understand the influence of the coronavirus disease 2019 (COVID-19) pandemic on clinical autonomic education and research in Europe.

METHODS

We invited 84 European autonomic centers to complete an online survey, recorded the pre-pandemic-to-pandemic percentage of junior participants in the annual congresses of the European Federation of Autonomic Societies (EFAS) and European Academy of Neurology (EAN) and the pre-pandemic-to-pandemic number of PubMed publications on neurological disorders.

RESULTS

Forty-six centers answered the survey (55%). Twenty-nine centers were involved in clinical autonomic education and experienced pandemic-related didactic interruptions for 9 (5; 9) months. Ninety percent (n = 26/29) of autonomic educational centers reported a negative impact of the COVID-19 pandemic on education quality, and 93% (n = 27/29) established e-learning models. Both the 2020 joint EAN-EFAS virtual congress and the 2021 (virtual) and 2022 (hybrid) EFAS and EAN congresses marked higher percentages of junior participants than in 2019. Forty-one respondents (89%) were autonomic researchers, and 29 of them reported pandemic-related trial interruptions for 5 (2; 9) months. Since the pandemic begin, almost half of the respondents had less time for scientific writing. Likewise, the number of PubMed publications on autonomic topics showed the smallest increase compared with other neurological fields in 2020-2021 and the highest drop in 2022. Autonomic research centers that amended their trial protocols for telemedicine (38%, n = 16/41) maintained higher clinical caseloads during the first pandemic year.

CONCLUSIONS

The COVID-19 pandemic had a substantial negative impact on European clinical autonomic education and research. At the same time, it promoted digitalization, favoring more equitable access to autonomic education and improved trial design.

Dysregulations in hemostasis, metabolism, immune response, and angiogenesis in post-acute COVID-19 syndrome with and without postural orthostatic tachycardia syndrome: a multi-omic profiling study

Post-acute COVID-19 (PACS) are associated with cardiovascular dysfunction, especially postural orthostatic tachycardia syndrome (POTS). Patients with PACS, both in the absence or presence of POTS, exhibit a wide range of persisting symptoms long after the acute infection. Some of these symptoms may stem from alterations in cardiovascular homeostasis, but the exact mechanisms are poorly understood. The aim of this study was to provide a broad molecular characterization of patients with PACS with (PACS + POTS) and without (PACS-POTS) POTS compared to healthy subjects, including a broad proteomic characterization with a focus on plasma cardiometabolic proteins, quantification of cytokines/chemokines and determination of plasma sphingolipid levels. Twenty-one healthy subjects without a prior COVID-19 infection (mean age 43 years, 95% females), 20 non-hospitalized patients with PACS + POTS (mean age 39 years, 95% females) and 22 non-hospitalized patients with PACS-POTS (mean age 44 years, 100% females) were studied. PACS patients were non-hospitalized and recruited ≈18 months after the acute infection. Cardiometabolic proteomic analyses revealed a dysregulation of ≈200 out of 700 analyzed proteins in both PACS groups vs. healthy subjects with the majority (> 90%) being upregulated. There was a large overlap (> 90%) with no major differences between the PACS groups. Gene ontology enrichment analysis revealed alterations in hemostasis/coagulation, metabolism, immune responses, and angiogenesis in PACS vs. healthy controls. Furthermore, 11 out of 33 cytokines/chemokines were significantly upregulated both in PACS + POTS and PACS-POTS vs. healthy controls and none of the cytokines were downregulated. There were no differences in between the PACS groups in the cytokine levels. Lastly, 16 and 19 out of 88 sphingolipids were significantly dysregulated in PACS + POTS and PACS-POTS, respectively, compared to controls with no differences between the groups. Collectively, these observations suggest a clear and distinct dysregulation in the proteome, cytokines/chemokines, and sphingolipid levels in PACS patients compared to healthy subjects without any clear signature associated with POTS. This enhances our understanding and might pave the way for future experimental and clinical investigations to elucidate and/or target resolution of inflammation and micro-clots and restore the hemostasis and immunity in PACS.

Analysis of the correlation between heart rate variability and palpitation symptoms in female patients with long COVID

Objectives

To analyze the correlation between heart rate variability (HRV) and palpitation symptoms in female patients with long COVID.

Methods

A total of 272 female healthcare workers who were infected with SARS-CoV-2 for the first time in December 2022 at Fuzhou First Hospital affiliated with Fujian Medical University, were selected as study subjects. These subjects were divided into three groups based on their symptoms: a group with palpitations (70 cases), a group without palpitations but with other symptoms (124 cases), and a group consisting of asymptomatic cases (78 cases). The study compared the general information, COMPASS-31 scores, quality of life scores, and HRV parameters among the three groups. Furthermore, it analyzed the factors influencing palpitation symptoms in female patients with long COVID.

Results

Compared to the other two groups, the HRV parameters SDNN, HRVIndex, LF, and TP were significantly reduced in the group with palpitations (p < 0.05). Multivariate analysis revealed that HRVIndex (p = 0.016; OR: 0.966, 95% CI: 0.940∼0.994) had a significant impact on palpitation symptoms in female patients with long COVID.

Conclusions

The symptoms of palpitations in female patients with long COVID were found to be related to HRV parameters. Autonomic dysfunction may be connected to the occurrence of palpitation symptoms in long COVID.

Postural orthostatic tachycardia syndrome and other related dysautonomic disorders after SARS-CoV-2 infection and after COVID-19 messenger RNA vaccination

The COVID-19 pandemic has caused a challenge for our society due to the post-acute sequelae of the disease. Persistent symptoms and long-term multiorgan complications, known as post-acute COVID-19 syndrome, can occur beyond 4 weeks from the onset of the COVID-19 infection. Postural orthostatic tachycardia syndrome (POTS) is considered a variety of dysautonomia, which is characterized by chronic symptoms that occur with standing and a sustained increase in heart rate, without orthostatic hypotension. POTS can lead to debilitating symptoms, significant disability, and impaired quality of life. In this narrative review, the etiopathogenic basis, epidemiology, clinical manifestations, diagnosis, treatment, prognosis, and socioeconomic impact of POTS, as well as other related dysautonomic disorders, after COVID-19 infection and SARS-CoV-2 postvaccination, were discussed. After a search conducted in March 2023, a total of 89 relevant articles were selected from the PubMed, Google Scholar, and Web of Science databases. The review highlights the importance of recognizing and managing POTS after COVID-19 infection and vaccination, and the approach to autonomic disorders should be known by all specialists in different medical areas. The diagnosis of POTS requires a comprehensive clinical assessment, including a detailed medical history, physical examination, orthostatic vital signs, and autonomic function tests. The treatment of POTS after COVID-19 infection or vaccination is mainly focused on lifestyle modifications, such as increased fluid and salt intake, exercise, and graduated compression stockings. Pharmacotherapy, such as beta-blockers, fludrocortisone, midodrine, and ivabradine, may also be used in selected cases. Further research is needed to understand the underlying mechanisms, risk factors, and optimal treatment strategies for this complication.

Autonomic Dysfunction Related to Postacute SARS-CoV-2 Syndrome

Persistence of symptoms beyond the initial acute phase of coronavirus disease-2019 (COVID-19) is termed postacute SARS-CoV-2 (PASC) and includes neurologic, autonomic, pulmonary, cardiac, psychiatric, gastrointestinal, and functional impairment. PASC autonomic dysfunction can present with dizziness, tachycardia, sweating, headache, syncope, labile blood pressure, exercise intolerance, and "brain fog." A multidisciplinary team can help manage this complex syndrome with nonpharmacologic and pharmacologic interventions.

Assessment and Therapeutic Modulation of Heart Rate Variability: Potential Implications in Patients with COVID-19

Cardiac damage has been attributed to SARS-CoV-2-related pathology contributing to increased risk of vascular events. Heart rate variability (HRV) is a parameter of functional neurocardiac integrity with low HRV constituting an independent predictor of cardiovascular mortality. Whether structural cardiac damage translates into neurocardiac dysfunction in patients infected with SARS-CoV-2 remains poorly understood. Hypothesized mechanisms of possible neurocardiac dysfunction in COVID-19 comprise direct systemic neuroinvasion of autonomic control centers, ascending virus propagation along cranial nerves and cardiac autonomic neuropathy. While the relationship between the autonomic nervous system and the cytokine cascade in general has been studied extensively, the interplay between the inflammatory response caused by SARS-CoV-2 and autonomic cardiovascular regulation remains largely unclear. We reviewed the current literature on the potential diagnostic and prognostic value of autonomic neurocardiac function assessment via analysis of HRV including time domain and spectral analysis techniques in patients with COVID-19. Furthermore, we discuss potential therapeutic targets of modulating neurocardiac function in this high-risk population including HRV biofeedback and the impact of long COVID on HRV as well as the approaches of clinical management. These topics might be of particular interest with respect to multimodal pandemic preparedness concepts.

[Neurological forms of long COVID in adults: Critical approach]

Now recognized by health authorities, long COVID is identified as a frequent condition complicating the evolution of SARS-CoV-2 infection. Its polymorphic and sometimes disconcerting clinical expression raises questions about its mechanism. Patterns of clinical expression suggest extensive involvement of the nervous system through an almost ubiquitous cognitive complaint. This article reviews the neurological symptoms and forms of these patients, and the neuropsychological explorations aimed at objectifying a cognitive deficit. The studies published until now confronted with the clinical mode of expression, did not make it possible to define a deficit neuropsychological profile at the level of the groups, and evoked more a functional impairment than a lesion. However, each series mentions a small number of patients in whom a cognitive deficit is objectified. The uncertainties about the causes of the prolonged forms of COVID, the heterogeneity of the published studies, and the virtual absence of temporal evolution data should make one cautious about the interpretation of these data but should in no way delay or prevent taking into account care of these patients.

The Impact of COVID-19 upon Intracardiac Hemodynamics and Heart Rate Variability in Stable Coronary Artery Disease Patients

The aim. To study the impact of COVID-19 upon intracardiac hemodynamics and heart rate variability (HRV) in stable coronary artery disease (SCAD) patients. Materials and methods. In this cross-sectional study we analyzed clinical and instrumental data obtained from a sample of 80 patients. The patients were divided into three groups: group 1 included patients with SCAD without COVID-19 (n=30), group 2 included patients with SCAD and COVID-19 (n=25), and group 3 included patients with COVID-19 without SCAD (n=25). The control group included 30 relatively healthy volunteers. Results. The changes in intracardiac hemodynamics and HRV in group 2 were characterized by the impaired left ventricular systolic and diastolic function, dilation of both ventricles and elevated systolic pulmonary artery pressure. Left ventricular end-diastolic volume was higher in group 2 (205±21 ml) than that in group 1 (176±33 ml; р<0.001) and group 3 (130±21 ml; р<0.001). Patients in the groups 1–3, compared to controls, presented with the decrease in the overall HRV (by standard deviation [SD] of all NN intervals [SDNN]; SD of the averages of NN intervals in all 5 min segments of the entire recording; and mean of the SDs of all NN intervals for all 5 min segments of the entire recording) and parasympathetic activity (root-mean-square difference of successive NN intervals; the proportion derived by dividing the number of interval differences of successive NN intervals greater than 50 ms [NN50] by the total number of NN intervals [pNN50], and high frequency spectral component), along with QT interval prolongation and increase in its variability. Group 2 demonstrated the most advanced changes in HRV (by SDNN and pNN50) and both QT interval characteristics. Conclusions. The patients with SCAD and concomitant COVID-19, along with both ventricles dilation and intracardiac hemodynamics impairment, presented with the sings of autonomic dysfunction, QT interval prolongation and increase in its variability. The heart rate variability and QT interval characteristics should be additionally considered in the management of such patients.