Prevention of Syncope Trial (POST): a randomized, placebo-controlled study of metoprolol in the prevention of vasovagal syncope

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.

[Syncopes - differential diagnoses and treatment]

Syncope is a sudden loss of consciousness (transient loss of consciousness, TLOC) caused by a lack of cerebral perfusion that resolves spontaneously and completely after a short period of time 1. With a lifetime prevalence of 40% and constituting about 1% of all emergency department admissions, syncope is a common and medically relevant problem 2 3. The underlying causes of syncope are diverse and associated with significantly different prognoses. A structured approach is essential to identify high-risk patients and ensure appropriate treatment. This article aims at providing an overview of the current recommendations for the diagnosis and treatment of syncope.

Endocardial ablation of epicardial ganglionated plexi: history, open questions and future prospects of cardioneuroablation

Neurocardiogenic syncope is the most common cause of transient loss of consciousness and considerably reduces quality of life. Pharmacological and pacing therapy may not be fully efficacious and complications related to implanted hardware must be considered. In this context, cardioneuroablation (CNA) has been proposed to attenuate the vagal reflex with elimination of cardioinhibition. It has been shown that CNA is able to eliminate recurrences of syncope in over 90% of cases and no major complications are reported in the current literature. Despite these encouraging findings, CNA is only mentioned in current guidelines as a possible alternative treatment and has no real indication class. The diversity of mapping techniques, the absence of direct denervation control, the lack of a precise endpoint, the possible placebo effect, the short follow-up, and the question of the learning curve represent the major limitations of this promising procedure. The aim of this review was to look over the existing literature, analysing the novelties, the limitations, the unresolved issues and the outcome of CNA.

Cardioneuroablation for severe neurocardiogenic syncope

INTRODUCTION AND OBJECTIVES

Cardioneuroablation (CNA), a technique based on radiofrequency ablation of cardiac vagal ganglia, was developed to treat recurrent vasovagal syncope (VVS) with a predominant cardioinhibitory component, as an alternative to pacemaker implantation. The aim of our study was to evaluate the safety and success rate of CNA guided by extracardiac vagal stimulation in patients with highly symptomatic cardioinhibitory VVS.

METHODS

Prospective study of patients who underwent anatomically guided CNA at two cardiology centers. All patients had a history of recurrent syncope with a predominant cardioinhibitory component and refractory to conventional measures. Acute success was determined by the absence or significant reduction of cardiac parasympathetic response to extracardiac vagal stimulation. The primary endpoint was the recurrence of syncope during follow-up.

RESULTS

In total, 19 patients (13 males; mean age 37.8±12.9 years) were included. Ablation was acutely successful in all patients. One patient had a convulsive episode after the procedure, which was deemed unrelated to the ablation, requiring admission to intensive care but without sequelae. No other complications occurred. At a mean follow-up of 21.0±13.2 months (range 3-42 months), 17 patients remained free of syncope. The remaining two patients had recurrence of syncope and, despite undergoing a new ablation procedure, required pacemaker implantation during follow-up.

CONCLUSION

Cardioneuroablation, confirmed by extracardiac vagal stimulation, appears to be an effective and safe treatment option for highly symptomatic patients with refractory VVS with a predominant cardioinhibitory component, providing a new potential approach as an alternative to pacemaker implantation.

Twenty-five years of research on syncope

Over the last 25 years, the Europace journal has greatly contributed to dissemination of research and knowledge in the field of syncope. More than 400 manuscripts have been published in the journal. They undoubtedly improved our understanding of syncope. This symptom is now clearly differentiated from other forms of transient loss of consciousness. The critical role of vasodepression and/or cardioinhibition as final mechanisms of reflex syncope is emphasized. Current diagnostic approach sharply separates between cardiac and autonomic pathways. Physiologic insights have been translated, through rigorously designed clinical trials, into non-pharmacological or pharmacological interventions and interventional therapies. The following manuscript is intended to give the reader the current state of the art of knowledge of syncope by highlighting landmark contributions of the Europace journal.

Selective anatomical catheter ablation of left atrial ganglionated plexus for vasovagal syncope: Left superior and right anterior ganglionated plexus ablation

BACKGROUND

Vasovagal syncope (VVS) is one of the most common causes of syncope. Traditional treatment has not achieved satisfactory results. The purpose of this study was to assess the feasibility and efficacy of selective anatomical catheter ablation of left atrial ganglionated plexus (GP) as a therapeutic strategy for the patients of symptomatic VVS.

METHODS

A total of 70 patients with at least once recurrent syncopal episode of VVS with a positive head-up tilt test were enrolled. They were divided into GP ablation group and control group. Patients in GP ablation group received anatomical catheter ablation of left superior ganglionated plexus (LSGP) and right anterior ganglionated plexus (RAGP). Patients in the control group were guideline-directed conventional therapy. The primary endpoint was VVS recurrences. The secondary endpoint was the recurrence of syncope and prodrome events.

RESULTS

There were no statistical differences in clinical characteristics between the ablation group (n = 35) and the control group (n = 35). Over a follow-up of 12 months, the ablation group had significantly lower syncope recurrence compared with the control group (5.7% vs. 25.7%, p = .02), and the ablation group had significantly lower syncope and prodrome recurrence compared with the control group (11.4% vs. 51.4%, p < .001). In GP ablation, 88.6% of the patients showed significant vagal response during LSGP ablation, and 88.6% of the patients showed significantly increased heart rate during RAGP ablation.

CONCLUSIONS

For patients with recurrent VVS, selective anatomical catheter ablation of LSGP and RAGP is superior to conventional therapy in reducing syncope recurrence.

Markers for predicting the efficacy of beta-blockers in vasovagal syncope management in children: A mini-review

Vasovagal syncope (VVS) is a common subtype of neurally mediated syncope. It is prevalent in children and adolescents, and critically affects the quality of life of patients. In recent years, the management of pediatric patients with VVS has received extensive attention, and β-blocker serves as an important choice of the drug therapy for children with VVS. However, the empirical use of β-blocker treatment has limited therapeutic efficacy in patients with VVS. Therefore, predicting the efficacy of β-blocker therapy based on biomarkers related to the pathophysiological mechanism is essential, and great progress has been made by applying these biomarkers in formulating individualized treatment plans for children with VVS. This review summarizes recent advances in predicting the effect of β-blockers in the management of VVS in children.

Pharmacologic prevention of recurrent vasovagal syncope: A systematic review and network meta-analysis of randomized controlled trials

Vasovagal syncope (VVS) is a transient loss of consciousness that currently imposes a high burden on health care systems with limited evidence of the comparative efficacy of available pharmacologic interventions. This study aims to compare all pharmacologic therapies suggested in randomized controlled trials (RCTs) through systematic review and network meta-analysis. A systematic search in PubMed, Embase, Web of Science, and Cochrane Library was conducted to identify RCTs evaluating pharmacologic therapies for patients with VVS. The primary outcome was spontaneous VVS recurrence. The secondary outcome was a positive head-up tilt test (HUTT) after receiving intervention, regarded as a lower level of evidence. Pooled risk ratio (RR) with 95% confidence interval (CI) was calculated using random-effect network meta-analysis. Pairwise meta-analysis for comparison with placebo was also performed when applicable. The surface under the cumulative ranking curve analysis was conducted to rank the treatments for each outcome. Twenty-eight studies with 1744 patients allocated to different medications or placebo were included. Network meta-analysis of the reduction in the primary outcome showed efficacy for midodrine (RR 0.55; 95% CI 0.35-0.85) and fluoxetine (especially in patients with concomitant anxiety) (RR 0.36; 95% CI 0.16-0.84). In addition, midodrine and atomoxetine were superior to other treatment options, considering positive HUTT (RR 0.37; 95% CI 0.23-0.59; and RR 0.49; 95% CI 0.28-0.86, respectively). Overall, midodrine was the only agent shown to reduce spontaneous syncopal events. Fluoxetine also seems to be beneficial but should be studied further in RCTs. Our network meta-analysis did not find evidence of the efficacy of any other medication.

Current approach to the treatment of vasovagal syncope in adults

Vasovagal syncope (VVS) is the most common cause of transient loss of consciousness. Although not associated with mortality, it causes injuries, reduces quality of life, and is associated with anxiety and depression. The European and North American cardiac societies recently published syncope clinical practice guidelines. Most patients with VVS do well after specialist evaluation, reassurance and education. Adequate hydration, increased salt intake when not contraindicated, and careful withdrawal of diuretics and specific hypotension-inducing drugs are a reasonable initial strategy. Physical counterpressure maneuvers might be helpful but can be of limited efficacy in older patients and those with short or no prodromes. Orthostatic training lacks long term efficacy and is troubled by non-compliance. Yoga might be helpful, although the biomedical mechanism is unknown. Almost a third of VVS patients continue to faint despite these conservative measures. Metoprolol was not helpful in a pivotal randomized clinical trial. Fludrocortisone and midodrine significantly reduce syncope recurrences with tolerable side effects, when titrated to target doses. Pacing therapy with specialized sensors appears promising in carefully selected population who have not responded conservative measures. Cardioneuroablation may be helpful but has not been studied in a formal clinical trial.

Compression stockings for treating vasovagal syncope (COMFORTS-II) trial: Rationale and design of a triple-blind, multi-center, randomized controlled trial

BACKGROUND

Reduced venous return is an important trigger of vasovagal syncope (VVS). Elastic compression stockings (ECS) can modify venous return and be of therapeutic interest; however, evidence for ECS efficacy in VVS is scarce. This randomized controlled trial was designed to address the issue.

METHODS

COMFORTS-II is a multicenter, triple-blind, parallel design, randomized controlled trial aimed to assess the efficacy of ECS in preventing VVS recurrences. Using central online randomization, 268 participants will be allocated to 2 arms (1:1 ratio), wearing intervention ECS (25-30 mm Hg pressure) or sham ECS (≤10 mm Hg pressure). All participants will receive standard VVS treatment in the form of education, and lifestyle modification recommendations (drinking 2-3 l/d of fluids and consuming 10 g/d-roughly half a tablespoon-of table salt). Adherence to ECS treatment will be evaluated through diary sheets, and compared between study arms. Follow-up continues for 1 year, and is conducted via a 24/7 phone line available to patients and trimonthly visits. The co-primary outcomes are proportion of participants with any syncopal recurrence and time to first syncopal episode. Secondary outcomes include frequency of VVS spells, time intervals between recurrences, and incidence of any patient-reported adverse effects.

CONCLUSION

To the best of our knowledge, COMFORTS-II is the first clinical trial to assess ECS efficacy among patients with VVS, addressing an important gap in evidence for VVS treatments.

Biomarkers and Hemodynamic Parameters in the Diagnosis and Treatment of Children with Postural Tachycardia Syndrome and Vasovagal Syncope

In children, vasovagal syncope and postural tachycardia syndrome constitute the major types of orthostatic intolerance. The clinical characteristics of postural tachycardia syndrome and vasovagal syncope are similar but their treatments differ. Therefore, their differential diagnosis is important to guide the correct treatment. Therapeutic methods vary in patients with the same diagnosis because of different pathomechanisms. Hence, in patients with vasovagal syncope or postural tachycardia syndrome, routine treatments have an unsatisfactory efficacy. However, biomarkers could increase the therapeutic efficacy significantly, allowing for an accurate and detailed assessment of patients and leading to improved therapeutic effects. In the present review, we aimed to summarize the current state of research into biomarkers for distinguishing the diagnosis of pediatric vasovagal syncope from that of postural tachycardia syndrome. We also discuss the biomarkers that predict treatment outcomes during personalized therapy for each subtype.

Effect of psychotherapy on recurrence of events and quality of life in patients with vasovagal syncope

Emotional distress is related to recurrence of syncope compromising patient's quality of life (QoL). The aim of this study was to determine if weekly sessions of psychotherapy reduce recurrence of events and improve QoL by SF-36 among patients with refractory vasovagal syncope. A randomised controlled pilot trial including 10 patients with recurrent vasovagal syncope and positive tilt table test was conducted. Known cardiac disease and ongoing psychotherapeutic interventions were the main exclusion criteria. All patients received standard of care treatment. Additionally, after randomisation, half of the patients underwent weekly sessions of psychotherapy for 12 months. Analysis of recurrence of events and QoL showed no significant change in the control group but, in the intervention group, there was a significant reduction in the rate of near-syncope episodes per month (5.7 ± 1.4 × 1.7 ± 1.0; P < 0.01), syncope in 1 year (4.6 ± 0.9 × 1.0 ± 0.7; P < 0.01) and a significant improvement in the overall assessment of QoL (44.1 ± 10.0 vs. 70.3 ± 10.3, P < 0.01). In conclusion, patients with refractory vasovagal syncope undergoing regular psychotherapeutic intervention had less recurrence of events and improved their quality of life in 1 year.

Trial Registration: ClinicalTrials.gov number, NCT04252729.

Effect of Yoga on Clinical Outcomes and Quality of Life in Patients With Vasovagal Syncope (LIVE-Yoga)

OBJECTIVES

This study aims to determine the impact of yoga as an adjunct to standard therapy versus standard therapy alone on the symptomatic burden in patients with recurrent vasovagal syncope (VVS).

BACKGROUND

There is a significant reduction in the quality of life (QoL) of patients with recurrent VVS. Existing management therapies have been largely ineffective. Recent trials have demonstrated the efficacy of yoga in diseases with autonomic imbalance, suggesting its possible utility in VVS.

METHODS

Patients with recurrent VVS were randomized to receive either a specialized yoga training program in addition to current guideline-based therapy (intervention arm, group 1) or current guideline-based therapy alone (control arm, group 2). The primary outcome was a composite of the number of episodes of syncope and presyncope at 12 months. Secondary outcomes included QoL assessment by World Health Organization Quality of Life Brief Field questionnaire (WHOQoL-BREF) scores and Syncope Functional Status Questionnaire scores at 12 months, head up tilt test, and heart rate variability at 6 weeks.

RESULTS

A total of 55 patients underwent randomization. The mean number of syncopal or presyncopal events at 12 months was 0.7 ± 0.7 in the intervention arm compared to 2.52 ± 1.93 in the control arm (P < 0.01). In the intervention arm, 13 (43.3%) patients remained free of events versus 4 (16.0%) patients in the control arm (P = 0.02). QoL at 12 months showed significant improvement of all Syncope Functional Status Questionnaire scores and 2 domains of WHOQoL-BREF scores (P < 0.05).

CONCLUSIONS

Yoga as adjunctive therapy is superior to standard therapy alone in reducing the symptomatic burden and improving QoL in patients with recurrent VVS.

Management of vasovagal syncope

Vasovagal syncope (VVS) is a very common form of fainting. Treatment begins with patient education about the mechanism of fainting, and the non-lethal nature of vasovagal syncope. In this article, we review several non-pharmacological approaches that form the foundation of our current treatments. These include increases in dietary salt and water intake, the use of compression garments, physical counter-maneuvers and tilt-training. When these approaches are inadequate, medications can sometimes be effective. While the evidence base for the pharmacological treatment of VVS is modest, recent trial data have found drugs to be useful in placebo-controlled randomized trials. For select patients, and those patients more refractory to medications, procedural treatments may be an option. In this review, we discuss the current state of evidence for the non-pharmacological and pharmacological treatments for VVS, as well as some novel, emerging therapies for VVS.

Management strategies for vasovagal syncope

Vasovagal syncope (VVS) (or neurocardiogenic syncope) is a common clinical condition that is challenging to both physicians and patients alike. Severe episodes of recurrent syncope can result in physical injury as well as psychological distress. This article provides a brief overview of current management strategies and a detailed overview of therapeutic modalities such as closed loop stimulation (CLS) and cardioneuroablation (CNA).

Midodrine for the Prevention of Vasovagal Syncope : A Randomized Clinical Trial

BACKGROUND

Recurrent vasovagal syncope is common, responds poorly to treatment, and causes physical trauma and poor quality of life. Midodrine prevents hypotension and syncope during tilt tests in patients with vasovagal syncope.

OBJECTIVE

To determine whether midodrine can prevent vasovagal syncope in usual clinical conditions.

DESIGN

Randomized, double-blind, placebo-controlled clinical trial. (ClinicalTrials.gov: NCT01456481).

SETTING

25 university hospitals in Canada, the United States, Mexico, and the United Kingdom.

PATIENTS

Patients with recurrent vasovagal syncope and no serious comorbid conditions.

INTERVENTION

Patients were randomly assigned 1:1 to placebo or midodrine and followed for 12 months.

MEASUREMENTS

The primary outcome measure was the proportion of patients with at least 1 syncope episode during follow-up.

RESULTS

The study included 133 patients who had had a median of 6 syncope episodes in the prior year (median age, 32 years; 73% female). Compared with patients receiving placebo, fewer patients receiving midodrine had at least 1 syncope episode (28 of 66 [42%] vs. 41 of 67 [61%]). The relative risk was 0.69 (95% CI, 0.49 to 0.97; P = 0.035). The absolute risk reduction was 19 percentage points (CI, 2 to 36 percentage points), and the number needed to treat to prevent 1 patient from having syncope was 5.3 (CI, 2.8 to 47.6). The time to first syncope was longer with midodrine (hazard ratio, 0.59 [CI, 0.37 to 0.96]; P = 0.035; log-rank P = 0.031). Adverse effects were similar in both groups.

LIMITATION

Small study size, young and healthy patients, relatively short observation period, and high proportion of patients from 1 center.

CONCLUSION

Midodrine can reduce the recurrence of syncope in healthy, younger patients with a high syncope burden.

PRIMARY FUNDING SOURCE

The Canadian Institutes of Health Research.

The impact of atrial mechanical function on age-dependent presentation of neurocardiogenic syncope

Background

The contribution of atrial and ventricular function in neurocardiogenic syncope (NCS) pathophysiology is elusive.

Hypothesis

We assessed the influence of echocardiographic properties to the age of presentation and NCS recurrences.

Methods

We assigned 124 patients with symptoms suggesting NCS, to those with syncope initiation at age <35 (group A, n = 56) and >35 years (group B, n = 68). Echocardiographic indices were measured before head‐up tilt test (HUTT).

Results

A total of 55 had positive HUTT (44%) with a trend favoring group A (p = .08). Group A exhibited lower left atrial (LA) volume index (17 ± 6 vs. 22 ± 11 ml/m², p = .015), higher LA ejection fraction (69 ± 10 vs. 63 ± 11%, p = .008), LA peak strain (reservoir phase 41 ± 13 vs. 31 ± 14%, p = .001, contraction phase 27 ± 11 vs. 15 ± 10%, p < .001) and LA peak strain rate (reservoir phase 1.83 ± 1.04 vs. 1.36 ± 0.96 1/s, p = .012, conduit phase 2.36 ± 1.25 vs. 1.36 ± 0.78 1/s, p = .001). Group A showed smaller minimum right atrial (RA) volume, better RA systolic function, superior left ventricular diastolic indices, and lower filling pressures. Group A patients were more likely to have >3 recurrences (82.0% vs. 50.1%, p < .05).

Conclusions

Patients with younger age of NCS onset and more syncopal recurrences manifest smaller LA and RA dimensions with distinct patterns of systolic and diastolic function and better LA reservoir and contraction properties. These findings may indicate an increased susceptibility to preload reduction, thereby triggering the NCS mechanism.

Likelihood of injury due to vasovagal syncope: a systematic review and meta-analysis

AIMS

Vasovagal syncope (VVS) is the most common type of syncope and is usually considered a benign disorder. The potential for injury is worrisome but the likelihood is unknown. We aimed to determine the proportion of patients injured due to VVS.

METHODS AND RESULTS

A systematic search of studies published until August 2020 was performed in multiple medical and nursing databases. Included studies had data on the proportion of patients with injury due to VVS prior to study enrolment. Random effects methods were used. Twenty-three studies having 3593 patients met inclusion criteria. Patients were diagnosed clinically with VVS, and 82% had >2 syncopal episodes before enrolment. Tilt test was positive in 60% and 14 studies reported comorbidities (32.6% hypertensive). The weighted mean injury rate was 33.5% [95% confidence interval (CI): 27.3-40.5%]. The likelihood of injury correlated with population age (r = 0.4, P = 0.05), but not with sex, positive tilt test, or hypertension. The injury rates were 25.7% (95% CI: 19.1-32.8%) in studies with younger patients (mean age ≤50 years, n = 1803) and 43.4% (95% CI: 34.9-52.3%) in studies with older patients (P = 0.002). Nine studies reported major injuries; with a weighted mean rate of major injuries of 13.9% (95% CI: 9.5-19.8%).

CONCLUSION

Injuries due to syncope are frequent, occurring in 33% of patients with VVS. The risk of major injuries is substantial. Older patients are at higher risk. Clinicians should be aware of the risk of injuries when providing care and advice to patients with VVS.

Syncope in Commercial Pilots and New Regulatory Guidance

INTRODUCTION: Syncope is both incapacitating and unpredictable, presenting a significant challenge in aircrew assessment. Previous UK Civil Aviation Authority (CAA) guidance lacked transparency and relied heavily on specialist in-house cardiology and neurology opinion. A new algorithm was developed which elaborated and formalized the decision-making process. An analysis of its impact on historic cases was undertaken to ensure it aligned with previous certificatory outcomes.METHODS: The medical literature on syncope and the approaches of other national aviation authorities were reviewed to help inform the development of a new algorithm. Using syncope cases in the CAA database, regulatory outcomes generated using the new algorithm were compared with previous decisions in terms of time off from flying (TOF) and Operational Multi-Crew Limitation (OML) duration.RESULTS: There were 40 historic syncope cases (25 existing certificate holders,15 initial applicants) which were reassessed using the new algorithm. The mean TOF for existing pilots using the new algorithm was 7.1 9.8 (mean SD) vs. 4.2 3.5 mo under the old guidance with an OML duration of 21.4 34.9 vs. 24.5 25.2 mo. One less initial applicant experienced a delay to certification. Four cases with underlying pathology were detected using old and new guidance.DISCUSSION: The reassessment of cases showed no statistically significant difference in TOF and OML duration; this is a positive finding from a regulatory perspective, enabling algorithm-led decision-making with less reliance on in-house expertise. A similar approach may be useful in future updates to other areas of regulatory practice.Anderton RA, Mitchell SJ, ONunain SS. Syncope in commercial pilots and new regulatory guidance. Aerosp Med Hum Perform. 2021; 92(8):642649.

Low-blood pressure phenotype underpins the tendency to reflex syncope

BACKGROUND

We hypothesized that cardiovascular physiology differs in reflex syncope patients compared with the general population, predisposing such individuals to vasovagal reflex.

METHODS

In this multicohort cross-sectional study, we compared aggregate data of resting SBP, DBP, pulse pressure (PP) and heart rate (HR), collected from six community-based cohort studies (64 968 observations) with those from six databases of reflex syncope patients (6516 observations), subdivided by age decades and sex.

RESULTS

Overall, in male individuals with reflex syncope, SBP (-3.4 mmHg) and PP (-9.2 mmHg) were lower and DBP (+2.8 mmHg) and HR (+5.1 bpm) were higher than in the general population; the difference in SBP was higher at ages above 60 years. In female individuals, PP (-6.0 mmHg) was lower and DBP (+4.7 mmHg) and HR (+4.5 bpm) were higher than in the general population; differences in SBP were less pronounced, becoming evident only above 60 years. Compared with male individuals, SBP in female individuals exhibited slower increase until age 40 years, and then demonstrated steeper increase that continued throughout remaining life.

CONCLUSION

The patients prone to reflex syncope demonstrate a different resting cardiovascular haemodynamic profile as compared with a general population, characterized by lower SBP and PP, reflecting reduced venous return and lower stroke volume, and a higher HR and DBP, suggesting the activation of compensatory mechanisms. Our data contribute to a better understanding why some individuals with similar demographic characteristics develop reflex syncope and others do not.

VIDEO ABSTRACT

http://links.lww.com/HJH/B580.

Frequency of injuries associated with syncope in the prevention of syncope trials

AIMS

Syncope can lead to injuries. We determined the frequency, severity, and predictors of injuries due to syncope in cohorts of syncope patients.

METHODS AND RESULTS

Participants were enrolled in the POST2 (fludrocortisone) and POST4 (midodrine) vasovagal syncope (VVS) randomized trials, and POST3 enrolled patients with bifascicular block and syncope. Injury was defined as minor (bruising, abrasions), moderate (lacerations), and severe (fractures, burns, joint pain), and recorded up to 1 year after enrolment. A total of 459 patients (median 39 years) were analysed. There were 710 faints occurred in 186 patients during a 1-year follow-up. Fully 56/186 (30%) of patients were injured with syncope (12% of overall group). There were 102 injuries associated with the 710 faints (14%), of which 19% were moderate or severe injuries. Neither patient age, sex, nor the presence of prodromal symptoms associated with injury-free survival. Patients with bifascicular block were more prone to injury (relative risk 1.98, P = 0.018). Patients with ≥4 faints in the prior year had more injuries than those with fewer faints (relative risk 2.97, P < 0.0001), but this was due to more frequent syncope, and not more injuries per faint. In VVS patients, pharmacological therapy significantly reduced the likelihood of an injury due to a syncopal spell (relative risk 0.64, P = 0.015). Injury severity did not associate with age, sex, or prior-year syncope frequency.

CONCLUSION

Injuries are frequent in syncope patients, but only 4% of injuries were severe. None of age, sex, and prodromal symptoms associate with injury.

Atomoxetine as an adjunct to nonpharmacological treatments for preventing vasovagal attacks in patients with recurrent vasovagal syncope: A pilot randomized-controlled trial

BACKGROUND

Despite the reduced quality of life in patients with recurrent vasovagal syncope (VVS), pharmacologic treatment options remain limited. Studies indicate that norepinephrine reuptake inhibition reduces tilt-induced syncope/pre-syncope. This study aimed to evaluate the effects of atomoxetine on syncopal/pre-syncopal episodes in patients with recurrent VVS.

METHODS

In a placebo-controlled trial, we randomized patients with newly diagnosed VVS who experienced ≥3 syncopal episodes in the past three months to receive either atomoxetine (20 mg daily for two weeks followed by 40 mg daily for two weeks) or placebo. The primary endpoint was the combined number of syncopal and pre-syncopal episodes.

RESULTS

Among 843 patients initially screened, 46 were randomized (N = 23 in each group) and reevaluated at one and three months. Compared to placebo, atomoxetine significantly reduced the primary endpoint after three months (P < 0.001). In the atomoxetine arm, the median time to first pre-syncopal episode was 55 days (95% confidence interval (CI): 41.21-68.79), while this was 27 days (95% CI: 14.48-39.52) for the placebo group (P < 0.001). In a subgroup analysis of patients with systolic blood pressure < 110 mmHg, atomoxetine reduced the primary endpoint, and the number of syncopal and pre-syncopal episodes after one and three months. In this subgroup, the median time to first pre-syncopal attack was 56 days in the atomoxetine group as opposed to 9 days in the placebo group.

CONCLUSIONS

In this pilot study, the promising effects of atomoxetine in reducing syncopal/pre-syncopal episodes in recurrent VVS, especially with low blood pressure phenotype, warrant the conduction of future randomized trials.

The Association between Reasons for a Rapid Response Team Alert and Immediate Patient Management in Total Hip Arthroplasty Patients

BACKGROUND

The purpose of this study is to evaluate the value and efficacy of rapid response teams (RRTs) for different triggering events in total hip arthroplasty (THA) patients.

METHODS

A retrospective review of all RRT events at a single, tertiary referral center from 2014 to 2016 was performed. Inclusion criteria were defined as patients >18 years old that underwent primary or revision THA. Information queried included demographics, primary reason for RRT, Charlson Comorbidity Index (CCI), underlying etiology, whether any changes in management occurred, and whether the patient was uptriaged.

RESULTS

In total, 168 RRTs were called on 153 hip arthroplasty patients (mean age 65.2 ± 14.1 years; mean body mass index 32.3 ± 4.8, 66% female). Length of stay in RRT for primary and revision THA was 3.4 and 6.2 days, respectively. This was significantly longer than the length of stay for primary THA patients (2.4 days, P < .001) and revision THA patients (4.6 days, P = .005) that did not require an RRT. There were no mortalities. RRTs for hypotension/presyncope (11%) and for syncope (11%) resulted in significantly fewer changes in management (P < .01) than tachycardia (77%), hypoxia (57%), AMS (79%), and other (47%). RRTs for hypotension/presyncope (28%), syncope (15%), and hypoxia (30%) resulted in significantly fewer patients being uptriaged (P < .001) than tachycardia (81%). Hypotension/presyncope was found to be significantly more commonly due to volume depletion (67%) (P < .001) than other etiologies. Hypoxia was significantly more commonly due to atelectasis (57%) and opioids/oversedation (30.4%) (P = .037). AMS/delirium was also significantly more commonly caused by opioids/over-sedation (71%) (P < .001).

CONCLUSION

In patients undergoing THA, RRTs for hypotension/presyncopal symptoms and syncope were significantly less likely to result in changes in management or uptriaging compared to tachycardia. The most common etiologies were potentially preventable, including volume depletion and opioid use.

Non-Pharmacological and Pharmacological Management of Cardiac Dysautonomia Syndromes

Vasovagal syncope, postural orthostatic tachycardia syndrome, and inappropriate sinus tachycardia comprise a heterogenous group of common autonomic disorders that are associated with significant symptoms that impair quality of life. Clinical management of these disorders should prioritize conservative non-pharmacological therapies and consider incorporating pharmacological agents for recurrences. The selection and titration of medications may be complicated by the occurrence of potentially overlapping pathophysiological variants, differences in specific clinical presentations, and commonly associated comorbidities. However, with appropriate long-term management and specialist input, most patients note both symptomatic improvement and functional restoration over time.

Pathophysiology and Individualized Management of Vasovagal Syncope and Postural Tachycardia Syndrome in Children and Adolescents: An Update

Vasovagal syncope (VVS) and postural tachycardia syndrome (POTS) are the main forms of orthostatic intolerance in pediatrics and both are underlying causes of neurally-mediated syncope. In recent years, increasing attention has been paid to the management of VVS and POTS in children and adolescents. A number of potential mechanisms are involved in their pathophysiology, but the leading cause of symptoms varies among patients. A few studies thus have focused on the individualized treatment of VVS or POTS based on selected hemodynamic parameters or biomarkers that can predict the therapeutic effect of certain therapies and improve their effectiveness. This review summarizes the latest developments in individualized treatment of VVS and POTS in children and indicates directions for further research in this field.

A case report of one vasovagal syncope patient with third-degree atrioventricular block caused by SCN5A gene mutation and literature review

BACKGROUND

Vasovagal syncope (VVS) is common in children and significantly affects their quality of life. To our knowledge, this the first case report of SCN5A gene mutation associated with VVS and third-degree atrioventricular block (atrioventricular block, AVB), which could help pediatricians aware that VVS is not always a benign condition and help to identify VVS children at the risk of sudden death.

CASE PRESENTATION

A twelve-year-old male child was admitted to Beijing Children's Hospital of Capital Medical University for chest tightness for 9 days and syncope in July 2018. The child was diagnosed as VVS with third-degree AVB after complete investagations. A heterozygous mutation in the exon coding region of the SCN5A gene, C. 5851G > T (coding region 5551 nucleotide changed from G to T), was detected in the peripheral blood of the child. Electrophysiological examination and modified vagal ganglion radiofrequency ablation were performed in the child. The ECG playback was normal on the second day after operation. Holter showed no abnormality and no chest tightness or syncope occurred after 3 months and 1 year follow-up.

CONCLUSIONS

Our case report firstly reported that SCN5A mutation contributed to the pathogenesis of VVS with third-degree AVB. Vagal ganglion modified ablation have obtained good therapeutic effect. Gene analysis was of great value to the accurate diagnosis and treatment of VVS children.

Neurohormones in the Pathophysiology of Vasovagal Syncope in Adults

Vasovagal syncope (VVS) is the most common cause of syncope across all age groups. Nonetheless, despite its clinical importance and considerable research effort over many years, the pathophysiology of VVS remains incompletely understood. In this regard, numerous studies have been undertaken in an attempt to improve insight into the evolution of VVS episodes and many of these studies have examined neurohormonal changes that occur during the progression of VVS events primarily using the head-up tilt table testing model. In this regard, the most consistent finding is a marked increase in epinephrine (Epi) spillover into the circulation beginning at an early stage as VVS evolves. Reported alterations of circulating norepinephrine (NE), on the other hand, have been more variable. Plasma concentrations of other vasoactive agents have been reported to exhibit more variable changes during a VVS event, and for the most part change somewhat later, but in some instances the changes are quite marked. The neurohormones that have drawn the most attention include arginine vasopressin [AVP], adrenomedullin, to a lesser extent brain and atrial natriuretic peptides (BNP, ANP), opioids, endothelin-1 (ET-1) and serotonin. However, whether some or all of these diverse agents contribute directly to VVS pathophysiology or are principally a compensatory response to an evolving hemodynamic crisis is as yet uncertain. The goal of this communication is to summarize key reported neurohumoral findings in VVS, and endeavor to ascertain how they may contribute to observed hemodynamic alterations during VVS.

Timing of Circulatory and Neurological Events in Syncope

Syncope usually lasts less than a minute, in which short time arterial blood pressure temporarily falls enough to decrease brain perfusion so much that loss of consciousness ensues. Blood pressure decreases quickest when the heart suddenly stops pumping, which happens in arrhythmia and in severe cardioinhibitory reflex syncope. Loss of consciousness starts about 8 s after the last heart beat and circulatory standstill occurs after 10-15 s. A much slower blood pressure decrease can occur in syncope due to orthostatic hypotension Standing blood pressure can then stabilize at low values often causing more subtle signs (i.e., inability to act) but often not low enough to cause loss of consciousness. Cerebral autoregulation attempts to keep cerebral blood flow constant when blood pressure decreases. In reflex syncope both the quick blood pressure decrease and its low absolute value mean that cerebral autoregulation cannot prevent syncope. It has more protective value in orthostatic hypotension. Neurological signs are related to the severity and timing of cerebral hypoperfusion. Several unanswered pathophysiological questions with possible clinical implications are identified.

Pharmacological norepinephrine transporter inhibition for the prevention of vasovagal syncope in young and adult subjects: A systematic review and meta-analysis

BACKGROUND

Vasovagal syncope (VVS) significantly reduces quality of life, yet lacks effective medical therapies. Pharmacological norepinephrine transporter (NET) inhibition increases synaptic norepinephrine reuptake, which may be able to prevent hypotension, bradycardia, and syncope.

OBJECTIVE

The objective of this systematic review was to evaluate the ability of 3 NET inhibitors-reboxetine, sibutramine, and atomoxetine-to prevent head-up tilt-induced vasovagal outcomes in healthy participants and patients with VVS.

METHODS

Relevant studies were identified from Medical Literature Analysis and Retrieval System Online, Excerpta Medica Database, Cochrane Central Register of Controlled Trials, and Cumulative Index to Nursing and Allied Health Literature without language restriction from database inception to August 2019. All randomized controlled trials comparing the benefit of a NET inhibitor vs placebo in adult populations were selected for review and meta-analysis.

RESULTS

Four studies (101 participants) met inclusion criteria. The mean study size was 25 (range 11-56) participants. NET inhibition reduced the likelihood of vasovagal reactions marked by hypotension and bradycardia in healthy participants during head-up tilt testing (relative risk 0.15; 95% confidence interval 0.04-0.52; P = .003). This relative risk reduction also occurred in patients with VVS during head-up tilt when given atomoxetine (relative risk 0.49; 95% confidence interval 0.28-0.86; P = .01). This was achieved through heart rate compensation with NET inhibition toward the end of tilt testing (106 ± 32 beats/min vs 60 ± 22 beats/min; P < .001), which in turn preserved cardiac output and mean arterial pressure (71 ± 20 mm Hg vs 43 ± 13 mm Hg; P < .001) in the absence of significantly increased systemic vascular resistance.

CONCLUSION

NET inhibition prevents severe vasovagal reactions and syncope induced by head-up tilt testing in both healthy participants and patients with VVS. Pharmacological NET inhibition is a promising potential treatment of recurrent syncope.

Baroreflex Sensitivity Predicts Response to Metoprolol in Children With Vasovagal Syncope: A Pilot Study

Objective: To explore the role of baroreflex sensitivity (BRS) in the head-up tilt test (HUTT) in predicting the therapeutic response of vasovagal syncope (VVS) patients to metoprolol. Materials and Methods: Vasovagal syncope patients treated with metoprolol were enrolled in this study and were classified as responders or non-responders according to changes in their symptom scores before and after metoprolol treatment. Values of BRS in the supine position and at positive response occurrence in the HUTT were obtained, and BRS changes from supine to positive response occurrence were calculated. Differences between responders and non-responders were analyzed. Receiver operating characteristic curve analysis was performed to assess the value of BRS for predicting the therapeutic efficacy of metoprolol in pediatric patients with VVS. Results: Forty patients (14 boys; 11.8 ± 2.5 years) diagnosed with VVS were recruited in the study, 28 of whom were verified to be responders to metoprolol and 12 of whom were verified as non-responders. They did not show any differences in baseline characteristics and hemodynamics in the HUTT (p > 0.05). However, the responders had an obviously increased supine BRS value compared to the non-responders (16.9 ± 7.7 ms/mmHg vs. 7.6 ± 3.8 ms/mmHg; p < 0.01). No difference in BRS at positive response occurrence was observed between the two groups (8.9 ± 8.5 ms/mmHg vs. 10.6 ± 9.8 ms/mmHg; p > 0.05). Accordingly, the changes in the BRS of responders were more obvious than in non-responders (8.0 ± 7.8 ms/mmHg vs. -3.0 ± 10.4 ms/mmHg; p < 0.01). The area under the receiver operating characteristic curve for the predictive value of supine BRS was 0.887 (95% CI, 0.779-0.995; p < 0.01). A cut-off value of 10 ms/mmHg yielded a sensitivity and specificity of 82 and 83%, respectively, in predicting the therapeutic efficacy of metoprolol in pediatric VVS patients. The area under the receiver operating characteristic curve for the predictive value of BRS changes was 0.827 (95% CI, 0.693-0.962; p < 0.01). A cut-off value of 4 ms/mmHg yielded a sensitivity and specificity of 71 and 83%, respectively. Conclusion: Baroreflex sensitivity may predict the response of children with VVS to metoprolol.

Sex Differences in Vasovagal Syncope: A Post Hoc Analysis of the Prevention of Syncope Trials (POST) I and II

BACKGROUND

Vasovagal syncope (VVS) occurs in > 40% of individuals at least once in their lifetime. Sex-dependent differences in presentation and outcomes are not understood. We sought to determine differences in clinical presentation, treatment modalities, and outcomes of VVS between men and women.

METHODS

Data were collected as part of the Prevention of Syncope Trials (POST) I and II, 2 multicenter, placebo-controlled, randomized trials testing the effectiveness of metoprolol and fludrocortisone, respectively. Data regarding clinical presentation, outcomes, and time to first syncope event after randomization were compared.

RESULTS

Of the 418 patients (280 women and 138 men), women were younger at the time of first syncope event (21 vs 26 years P = 0.002) and had a lower baseline systolic blood pressure (117 vs 124 mm Hg, P < 0.001). Response to heat as a trigger for syncope was more common in women (68% vs 48%, P = 0.011). Clinical presentation in women consisted more commonly of feeling warm, having seizures, and experiencing more postsyncope fatigue (68% vs 54%, P = 0.048; 10% vs 2.7%, P = 0.045; 75% vs 59%, P = 0.017, respectively). Women were more likely to experience recurrent syncope after adjustment for prerandomization syncope burden and randomization assignment (hazard ratio, 1.56; 95% confidence interval, 1.10-2.22; P = 0.012).

CONCLUSION

Clinical presentation and provocative factors of VVS differ between men and women, as do recurrent events. Recognition of these differences may help target therapy specifically in men and women.

Diagnostic and therapeutic approach to cardioinhibitory reflex syncope: A complex and controversial issue

Syncope is defined as a transient loss of consciousness due to global cerebral hypoperfusion and is one of the leading causes of emergency department admission. The initial approach should focus on excluding non-syncopal causes for loss of consciousness and risk stratification for cardiac cause, in order to ensure an appropriate etiological investigation and therapeutic approach. Vasovagal syncope (VVS), the most common type of syncope, should be assumed once other causes are excluded. Pathophysiologically, the vasovagal reflex is the result of a paradoxical autonomic response, leading to hypotension and/or bradycardia. VVS has not been shown to affect mortality, but morbidity may be considerable in those with recurrent syncopal episodes. The management of VVS includes both non-pharmacological and pharmacological measures that act on various levels of the reflex arc that triggers the syncopal episode. However, most are of uncertain benefit given the scarcity of high-quality supporting evidence. Pacemaker therapy may be considered in recurrent refractory cardioinhibitory reflex syncope, for which it is currently considered a robust intervention, as noted in the European guidelines. Non-randomized and unblinded studies have shown a potential benefit of pacing in recurrent VVS, but double-blinded randomized controlled trials have not consistently demonstrated positive results. We performed a comprehensive review of the current literature and recent advances in cardiac pacing and pacing algorithms in VVS, and discuss the diagnostic and therapeutic approach to the complex patient with recurrent VVS and reduced quality of life.

Skin sympathetic nerve activity as a biomarker for syncopal episodes during a tilt table test

BACKGROUND

Autonomic imbalance is the proposed mechanism of syncope during a tilt table test (TTT). We have recently demonstrated that skin sympathetic nerve activity (SKNA) can be noninvasively recorded using electrocardiographic electrodes.

OBJECTIVE

The purpose of this study was to test the hypothesis that increased SKNA activation precedes tilt-induced syncope.

METHODS

We studied 50 patients with a history of neurocardiogenic syncope undergoing a TTT. The recorded signals were band-pass filtered at 500-1000 Hz to analyze nerve activity.

RESULTS

The average SKNA (aSKNA) value at baseline was 1.38 ± 0.38 μV in patients without syncope and 1.42 ± 0.52 μV in patients with syncope (P = .77). On upright tilt, aSKNA was 1.34 ± 0.40 μV in patients who did not have syncope and 1.39 ± 0.43 μV in patients who had syncope (P = .65). In all 14 patients with syncope, there was a surge of SKNA before an initial increase in heart rate followed by bradycardia, hypotension, and syncope. The peak aSKNA immediately (<1 minute) before syncope was significantly higher than baseline aSKNA (2.63 ± 1.22 vs 1.39 ± 0.43 μV; P = .0005). After syncope, patients were immediately placed in the supine position and aSKNA dropped significantly to 1.26 ± 0.43 μV; (P = .0004). The heart rate variability during the TTT shows a significant increase in parasympathetic tone during syncope (low-frequency/high-frequency ratio: 7.15 vs 2.21; P = .04).

CONCLUSION

Patients with syncope do not have elevated sympathetic tone at baseline or during the TTT except immediately before syncope when there is a transient surge of SKNA followed by sympathetic withdrawal along with parasympathetic surge.

Novel Therapeutic Options in the Management of Reflex Syncope

BACKGROUND

Syncope is a symptom associated with a wide range of pathological conditions, ranging from benign to life threatening. The most frequent is the reflex syncope that may be challenging to treat because of the complex and partially unknown pathophysiological mechanism that has to be addressed by the chosen therapy.

AREAS OF UNCERTAINTY

Head-up tilt testing is so far the only clinical test able to reproduce reflex syncope, but its diagnostic yield has been recently redefined. A new mechanism such as adenosine-sensitive syncope and idiopathic atrioventricular block have been recently described, and the appropriate therapy is not yet established. There is uncertainty on the efficacy of theophylline and on the use of cardiac pacing in these patients.

DATA SOURCES

Clinical trial published data and position paper from the main expert groups on fludrocortisone, midodrine, etilefrine, beta-blockers, and cardiac pacing as useful therapies for patients affected by reflex syncope.

THERAPEUTIC ADVANCES

Theophylline proved in observational trials to be efficient in preventing reflex syncope recurrences in patients with documented spontaneous paroxysmal conduction disorders comparable to cardiac pacing in a subgroup of patients. Reboxetine and sibutramine may elicit a significant pressor and tachycardic effect able to delay the onset of symptoms during head-up tilt testing. Droxidopa has short-term effects on improving the symptoms because of orthostatic hypotension. Cardiac pacing is effective in preventing reflex syncope recurrences with best results when the indication for pacemaker implantation was based on the documentation of bradycardia or asystole during the spontaneous event by a cardiac monitor. External compression using elastic bandage or compressive stockings is able to prevent the decrease in blood pressure in patients with orthostatic hypotension.

CONCLUSIONS

The optimal management of the complex diagnostic and therapeutic options can be achieved following a standardized and evidence-based approach to the patient with syncope.

Nonpharmacologic Treatments Alone are Enough to Prevent the Neurally Mediated Syncope: A 3 Years Follow-up Study

Background:

Recurrences are common in neurally mediated syncope. The aim of this study is the evaluation of the effectiveness of nonpharmacologic treatments alone in preventing of syncope relapse.

Methods:

70 patients (age 5–20 years) with neurally mediated syncope were enrolled. Thirty patients received pharmacologic therapies along with nonpharmacological methods, and 40 patients received just nonpharmacological treatments then followed them for 36 months. The incidences of different outcomes were analyzed with descriptive statistics using percentages.

Results:

The recurrence rate of syncope was significantly higher in pharmacological group than in nonpharmacological group in each period of the follow-up (P < 0.001).

Conclusions:

Nonpharmacologic treatment is very effective in the prevention of syncope relapses and can be a substitute for pharmacologic drugs in the initiation of treatment and if done correctly.

Quality of life improves in vasovagal syncope patients after clinical trial enrollment regardless of fainting in follow-up

BACKGROUND

Frequent syncope is linked to poorer health-related quality of life (HRQoL). Recurrent syncope has been observed to reduce in all groups after seeing a syncope expert and enrolling in a clinical trial. It is unknown if HRQoL improves with this reduction in syncope recurrence.

OBJECTIVES

We examined the change in HRQoL over time in vasovagal syncope (VVS) patients seen by a syncope expert and enrolled in a trial. We also explored whether change differed with treatment or the frequency of fainting during follow up.

METHODS

The Short Form Health Survey (SF36) was completed at baseline (BL), 6 m, and 12 m post-enrollment by VVS patients in the 1st and 2nd Prevention of Syncope Trials, which were multi-centered, randomized, placebo-controlled trials of metoprolol (POST) and fludrocortisone (POST2). Differences in HRQoL at BL, 6 m, and 12 m were analyzed and compared by faints in follow-up and randomization group.

RESULTS

Complete study data were available for 143 VVS patients (40 ± 17 years, 62% F). Over 12 months, patients reported improvement in all SF36 dimensions except for bodily pain. Post hoc analyses indicated that differences first occurred between BL and 6 m for all but general health. Fainting in follow-up or drug randomization group did not diminish the improvements. The baseline syncope burden was not different whether patients' HRQoL improved or not.

CONCLUSION

HRQoL of VVS patients improves over time after enrolling in a clinical trial, even with recurrent faints or randomization to placebo. Improvements may result from alternative factors, such as interaction with experts or patient adjustment.

Twenty-four-hour urine NE level as a predictor of the therapeutic response to metoprolol in children with recurrent vasovagal syncope

BACKGROUND

Vasovagal syncope (VVS) is a heterogeneous disorder that creates challenges for treatment. Metoprolol is an important therapeutic option for children with VVS.

AIMS

The study examined the predictive value of 24-h urine norepinephrine (NE) levels in the assessment of the therapeutic efficacy of metoprolol for recurrent VVS in children.

METHODS

Thirty-eight children with recurrent VVS and 20 healthy children were enrolled in our study. Twenty-four-hour urine NE levels were measured by LC-MS-MS. VVS children were diagnosed by BHUTT and/or SNHUTT, and received metoprolol treatment for 3 months. Symptom scoring was utilized to evaluate the therapeutic effect. A ROC curve was used to investigate the predictive value of 24-h urine norepinephrine levels.

RESULTS

There exists significant correlation between 24-h urine NE levels and supine systolic and diastolic blood pressures. The 24-h urine NE levels of responders (40.75 ± 12.86 μg/24 h) were higher than those of nonresponders (21.48 ± 6.49 μg/24 h), and there was a significant difference between the two groups (P < 0.001). A ROC curve of the predictive value of 24 h urine NE levels revealed that the area under the curve was 0.926. A cutoff value for 24-h urine NE level of 34.84 μg/24 h produced both high sensitivity (70%) and specificity (100%) in predicting the efficacy of metoprolol therapy for VVS.

CONCLUSIONS

Patients with high 24-h urine NE levels have higher supine systolic and diastolic pressures and more effective responses to metoprolol. A 24-h urine norepinephrine level of > 34.84 μg/24 h was an indicator of the effectiveness of metoprolol therapy for VVS in children.

Greater early epinephrine rise with head-up posture: A marker of increased syncope susceptibility in vasovagal fainters

BACKGROUND

Head-up tilt (HUT) is widely used for diagnostic evaluation of patients with suspected vasovagal syncope (VVS), but also offers an opportunity to study VVS pathophysiology. In this regard, it is known that plasma epinephrine (Epi) levels and Epi/norepinephrine (NE) ratio are markedly increased from baseline at the time of HUT-induced VVS. However, whether these changes contribute to VVS susceptibility remains uncertain.

OBJECTIVE

We hypothesized that if catecholamines contributed to VVS directly, then a greater increase of plasma Epi and Epi/NE ratio early during HUT would be associated with shorter time to syncope.

METHODS

The patient population comprised 33 individuals (14 men, 43 ± 2 years) with suspected VVS in whom 70° HUT reproduced symptoms. Arterial Epi and NE concentrations were collected at baseline (supine) and 2 minutes of HUT. Linear, exponential, and multiple regression were used to access the association between changing catecholamine levels and time to syncope.

RESULTS

Mean ± SD time to positive HUT was 11 (7.6) minutes. Higher plasma Epi levels (pg/mL) both at baseline and at 2 minutes upright correlated with shorter time to syncope (baseline, R = -0.35, P = 0.048; and 2 minutes, R = -0.58, P = 0.001). Similarly, a greater Epi/NE ratio at 2 minutes head-up correlated with earlier time to syncope (R = -0.49, P = 0.007). These relationships remained significant after adjusting for age and sex (P = 0.006 and 0.02, respectively).

CONCLUSION

Greater Epi levels and Epi/NE ratio early during HUT were associated with shorter time to VVS, suggesting a possible contribution to VVS susceptibility.

Selective ablation of atrial ganglionated plexus attenuates vasovagal reflex in a canine model

BACKGROUND

Atrial ganglionated plexus (GP) ablation was proved to have therapeutic effects on vasovagal syncope. The study aimed to investigate whether selective ablation of only right anterior GP (ARGP) and right inferior GP (IRGP) was effective in a canine model of vasovagal syncope.

METHODS

Seventeen mongrel dogs were divided into control (N = 10) and ablation group (N = 7). Bilateral thoracotomy was performed at the fourth intercostal space and ARGP and IRGP were ablated in the ablation group. A bolus of veratridine (15 ug/kg) was injected into the left atrium to induce vasovagal reflex. Surface electrocardiogram and blood pressure (BP) were continuously monitored. Heart rate (HR) variability was calculated to represent cardiac autonomic tone.

RESULTS

Veratridine injection induced vasovagal reflex in all dogs. HR decreased from 149 ± 17 to 89 ± 33 beats/min (P < 0.001) in the control group, while in the ablation group HR decreased from 141 ± 35 to 125 ± 34 beats/min (P = 0.032). The postveratridine HR in the ablation group was significantly higher than that in the control group (P = 0.045). A significantly less intense HR decrease was observed in the ablation group compared with control (-17 ± 16 vs -61 ± 34 beats/min, P = 0.006). Significant BP decreases were induced in both the groups (all P < 0.01), while no evident differences in postveratridine BP and the extent of BP decreases were found between the groups. HR variability revealed significant decrease in cardiac vagal tone after ablation [high-frequency power, 0.50 (0.17-1.05) vs 6.28 (0.68-8.99) ms² , P = 0.005].

CONCLUSIONS

Selective ablation of ARGP + IRGP weakened cardiac parasympathetic control and significantly attenuated the cardioinhibitory response in an animal model of vasovagal reflex. This ablation strategy might be effective for vasovagal syncope with evident cardioinhibitory response.

Treatment of Neurocardiogenic Syncope: From Conservative to Cutting-edge

Neurocardiogenic syncope is the most frequent cause of syncope in the general population. Many years have been spent on determining an effective treatment for this condition. Conventional treatment usually follows a tiered approach for neurocardiogenic syncope, as follows: first, lifestyle modification, including increased fluid intake and the introduction of physical counterpressure maneuvers, is tried; then the use of targeted pharmacologic therapy, particularly agents that support blood pressure or that drive blood pressure is attempted; and, finally, pacemaker implantation in patients with a predominant cardioinhibitory component to their syncopal episodes is performed. More recently, autonomic modulation with cardiac ganglion ablation has emerged as a promising treatment modality for patients refractory to traditional approaches. In this review, we sought to summarize the existing therapies for neurocardiogenic syncope and explore the latest research on new modalities of treatment.