A placebo-controlled trial of intravenous and oral disopyramide for prevention of neurally mediated syncope induced by head-up tilt

Therapeutic options for neurocardiogenic syncope: a meta-analysis of randomised trials with and without blinding

BACKGROUND

Neurocardiogenic syncope is a common condition with significant associated psychological and physical morbidity. The effectiveness of therapeutic options for neurocardiogenic syncope beyond placebo remains uncertain.

METHODS

The primary endpoint was the risk ratio (RR) of spontaneously recurring syncope following any therapeutic intervention. We also examined the effect of blinding on treatment efficacy. We identified all randomised trials which evaluated the effect of any pharmacological, device-based or supportive intervention on patients with a history of syncope. A systematic search was conducted on Medline, Embase, PubMed databases and Cochrane Central Register for Controlled Trials from 1950 to 25 April 2023. Event rates, their RRs and 95% CIs were calculated, and a random-effects meta-analysis was conducted for each intervention. Data analysis was performed in R using RStudio.

RESULTS

We identified 47 eligible trials randomising 3518 patients. Blinded trials assessing syncope recurrence were neutral for beta blockers, fludrocortisone and conventional dual-chamber pacing but were favourable for selective serotonin reuptake inhibitors (SSRIs) (RR 0.40, 95% CI 0.26 to 0.63, p<0.001), midodrine (RR 0.70, 95% CI 0.53 to 0.94, p=0.016) and closed-loop stimulation (CLS) pacing (RR 0.15, 95% CI 0.07 to 0.35, p<0.001). Unblinded trials reported significant benefits for all therapy categories other than beta blockers and consistently showed larger benefits than blinded trials.

CONCLUSIONS

Under blinded conditions, SSRIs, midodrine and CLS pacing significantly reduced syncope recurrence. Future trials for syncope should be blinded to avoid overestimating treatment effects.

PROSPERO REGISTRATION NUMBER

CRD42022330148.

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.

Cardioneuroablation for vasovagal syncope: A systematic review and meta-analysis

BACKGROUND

Cardioneuroablation (CNA) has emerged as promising therapy for patients with refractory vasovagal syncope (VVS).

OBJECTIVE

The purpose of this study was to provide a freedom from syncope estimate for CNA, including subgroup analysis by method and target of ablation.

METHODS

A systematic search was performed in MEDLINE and EMBASE according to the PRISMA guidelines until February 14, 2022. Observational studies and clinical trials reporting freedom from syncope were included. Meta-analysis was performed with a random-effects model.

RESULTS

A total of 465 patients were included across 14 studies (mean age 39.8 ± 4.0 year; 53.5% female). Different techniques were used to guide CNA: 50 patients (10.8%) by mapping fractionated electrograms, 73 (15.7%) with the spectral method, 210 (45.2%) with high-frequency stimulation, 73 (15.7%) with a purely anatomically guided method, and 59 (12.6%) with a combination. The target was biatrial in 168 patients (36.1%), left atrium only in 259 (55.7%), and right atrium only in 38 (8.2%). The freedom from syncope was 91.9% (95% confidence interval [CI] 88.1%-94.6%; I2 = 6.9%; P = .376). CNA limited to right atrial ablation was associated with a significant lower freedom from syncope (81.5%; 95% CI 51.9%-94.7%; P <.0001) vs left atrial ablation only (94.0%; 95% CI 88.6%--6.9%) and biatrial ablation (92.7%; 95% CI 86.8%-96.1%). Subgroup analysis according to the technique used to identify ganglionated plexi did not show any significant difference in freedom from syncope (P = .206).

CONCLUSION

This meta-analysis suggests a high freedom from syncope after CNA in VVS. Well-designed, double-blind, multicenter, sham-controlled randomized clinical trials are needed to provide evidence for future guidelines.

[Evaluation of Disopyramide Efficacy for Refractory Syncope in Heart Failure with Preserved Ejection Fraction Using Holter Electrocardiography: A Case Report]

The management of syncope is clinically important for heart failure (HF) patients. We herein describe a case on the efficacy of disopyramide for refractory syncope in HF with preserved ejection fraction (HFpEF). An 82-year-old man was hospitalized for respiratory distress and lower limb edema and was subsequently diagnosed with HFpEF. The use of diuretics improved HF symptoms; however, on day 10 after hospitalization, a rapid decrease in blood pressure and transient loss of consciousness developed. After neurologic examination, he was diagnosed with pure autonomic failure. Although he was administered midodrine 8 mg/d, fludrocortisone 0.1 mg/d, and droxidopa 300 mg/d, syncope was observed once a day on average. According to the Holter electrocardiogram, the patient's heart rate and coefficient of variation of R-R intervals (CVRR) during the day were unstable. In addition, high frequency power (parasympathetic nerve activity) was significantly higher than low frequency power (both sympathetic and parasympathetic nerves activity), suggesting that the parasympathetic nerves may have been highly active while the sympathetic nerves would have been blocked. On day 29, a pharmacist proposed disopyramide 300 mg/d, which blocks parasympathetic nerves and improves neural-mediated syncope, to the attending doctor. After the initiation of disopyramide, transient loss of consciousness was not observed. Furthermore, the diurnal variation in the heart rate and CVRR completely disappeared. In conclusion, disopyramide would be effective for refractory syncope in patients with HFpEF, and the Holter electrocardiogram may be a useful tool for the assessment of drug efficacy by pharmacists.

Pacemaker use for the treatment of reflex-mediated syncope: 40-year experience at a single paediatric institution

INTRODUCTION

Reflex-mediated syncope occurs in 15% of children and young adults. In rare instances, pacemakers are required to treat syncopal episodes associated with transient sinus pauses or atrioventricular block. This study describes a single centre experience in the use of permanent pacemakers to treat syncope in children and young adults.

MATERIALS AND METHODS

Patients with significant pre-syncope or syncope and pacemaker implantation from 1978 to 2018 were reviewed. Data collected included the age of presentation, method of diagnosis, underlying rhythm disturbance, age at implant, type of pacemaker implanted, procedural complications and subsequent symptoms.

RESULTS

Fifty patients were identified. Median age at time of the first syncopal episode was 10.2 (range 0.3-20.4) years, with a median implant age of 14.9 (0.9-34.3) years. Significant sinus bradycardia/pauses were the predominant reason for pacemaker implant (54%), followed by high-grade atrioventricular block (30%). Four (8%) patients had both sinus pauses and atrioventricular block documented. The majority of patients had dual-chamber pacemakers implanted (58%), followed by ventricular pacemakers (38%). Median follow-up was 6.7 (0.4-33.0) years. Post-implant, 4 (8%) patients continued to have syncope, 7 (14%) had complete resolution of their symptoms, and the remaining reported a decrease in their pre-syncopal episodes and no further syncope. Twelve (24%) patients had complications, including two infections and eight lead malfunctions.

CONCLUSIONS

Paediatric patients with reflex-mediated syncope can be treated with pacing. Complication rates are high (24%); as such, permanent pacemakers should be reserved only for those in whom asystole from sinus pauses or atrioventricular block has been well documented.

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.

Assessment of endothelin and copeptin as biomarkers for vasovagal syncope

BACKGROUND

The diagnosis of vasovagal syncope continues to be difficult despite the use of accurate histories, tilt testing and implantable loop recorders. A circulating biomarker might be useful to facilitate diagnoses. Both endothelin-1 and vasopressin are increased during positive tilt tests resulting in syncope. Copeptin is a stable cleavage product of vasopressin formation. We conducted a pilot study to assess the utility of endothelin-1 and copeptin as circulating biomarkers of vasovagal syncope.

METHODS

Three populations were studied: syncope patients, epilepsy patients and controls. Vasovagal syncope diagnosis was ascertained with the Calgary Syncope Score and epilepsy diagnosis was confirmed with EEG. Plasma levels of endothelin-1 were measured using by ELISA and copeptin levels were determined using an EIA kit.

RESULTS

Asymptomatic control subjects had mean age 35 ± 11 years (7/22 male); epileptic subjects had mean age 32 ± 7 years (4/15 male); and syncope subjects had mean age 33 ± 16 years (4 of 21 male). Circulating plasma levels of endothelin-1 and copeptin were no different among the three groups. Mean concentrations of endothelin-1 were as follows: syncope, 23 ± 32 pg/mL; controls, 21 ± 17 pg/mL; and epileptics, 18 ± 12 pg/mL. Mean concentrations of copeptin were as follows: syncope, 1·29 ± 0·79 ng/mL; controls, 1·25 ± 0·79 ng/mL; and seizures, 1·23 ± 0·45 ng/mL. There were no significant correlations between syncope frequency and copeptin or endothelin-1 levels.

CONCLUSION

Circulating plasma endothelin-1 and copeptin levels are not significantly different among populations of controls, syncope patients and seizure patients.

Therapy for Syncope

The diagnostic process in patients with syncope is not always easy and includes a detailed clinical history, physical examination and baseline electrocardiogram; according to the results of these initial approaches, some additional tests must be performed. Using this strategy, the cause of syncope is diagnosed in 60% to 80% of patients; in the remaining patients, risk stratification can be established to identify those patients at risk of having cardiac events or death at midterm follow-up. This article reviews the treatment of patients with syncope according to the different causes.

Prognostic Value of a Very Prolonged Asystole during Head-Up Tilt Test

BACKGROUND

Clinical significance and prognosis of a cardioinhibitory response to head-up tilt (HUT) test with a very prolonged asystole (≥30 seconds) is poorly studied. Our aim was to evaluate the treatment (including pacemaker implantation) and prognosis (syncope recurrence, syncope-related trauma, and overall mortality) of patients with a very prolonged asystole on a HUT test.

METHODS AND RESULTS

A retrospective study was conducted in two centers between January 2003 and December 2013 and included a total of 2,263 consecutive HUT tests (sensitized with isosorbide dinitrate) performed in 2,247 patients with syncope of unknown etiology. Cardioinhibitory response with asystole was observed in 149 (6.6%) of these tests (44.3% women, mean age 37 ± 18 years old, 16.1% in the nonpharmacological phase), with a median duration of asystole of 10 (6-19) seconds. Very prolonged asystole (≥30 seconds) was documented in 11 (0.5%) patients (45% women; mean age 40 ± 19 years; only one in the nonpharmacological phase, 9 minutes after HUT). The longest pause lasted 63 seconds. In all patients, avoidance of triggering factors and physical counterpressure maneuvers were recommended. Telephone follow-up was performed: in one patient, fludrocortisone was started; tilt training was conducted in one patient and none received a pacemaker. After a median follow-up of 42 (30-76) months, four patients (36%) had syncopal recurrences, one patient had a syncope-related injury (scalp laceration), and no patient died.

Treatment of neurally mediated reflex syncope

Neurally mediated reflex syncope, more commonly known as vasovagal syncope (VVS), remains the most common cause of transient loss of consciousness and syncope in all age groups. Most evidence assessing treatment of VVS derived from randomized clinical trials is limited. Multiple modalities of both nonpharmacologic and pharmacologic strategies have been tested, with conflicting results. The treatment of VVS has been directed toward interventions that interrupt the reflex response at different levels, hypothetically preventing the onset of syncope. This article reviews the available evidence of the different nonpharmacologic and pharmacologic therapies available for the treatment of recurrent VVS.

Overview of the contribution of recent clinical trials to advancement of syncope management

In this communication we review those trials that have contributed in recent years to improving our knowledge on the management (diagnosis and treatment) of syncope. In this regard, most recent trials focus on vasovagal syncope (VVS) and consequently these will be the focus of this manuscript. In essence, from a diagnostic perspective the ISSUE studies demonstrate the value of insertable loop recorders (ILR), while in terms of treatment, in the case of VVS current data strongly support use of non-pharmacologic treatment as a primary approach. There is no clear evidence supporting pharmacologic treatment with the possible exception of midodrine. Further, the most recent ISSUE trials suggest that in older very symptomatic patients with VVS in whom an asystole has been documented during spontaneous episode or possibly after ATP administration, implantation of a permanent pacemaker (PPM) can be effective. Which pacing or programming mode will be the more beneficial has not been completely clarified. Management of other forms of neurally-mediated syncope (e.g., carotid sinus syndrome) or other causes of syncope has not been addressed by clinical trials. In those cases, direction is provided by older evidence, the vast majority of which is based on observational reports or small non-randomized patient series.

Efficacy of lower limb compression in the management of vasovagal syncope--randomized, crossover study

INTRODUCTION

Vasovagal syncope (VS) is the most prevalent cause of transient loss of consciousness. The treatment consists of lifestyle modifications and pacemaker in some patients. The purpose of this study is to evaluate the effect of measures to compress the lower limbs in patients with recurrent episodes of VS submitted to the tilt-test (TT).

METHODS AND RESULTS

Twenty patients, average age 30.5 years (15-75), 13 (65%) female, with a clinical diagnosis of VS and previous TT with a positive result and who had at least one episode of syncope during the last year, were included in this placebo-controlled randomized crossover study. The patients underwent two consecutive TT, at a 1-hour interval, with and without compression by pneumatic compression boots with 40 mmHg at the heels and 30 mmHg for the legs. The blood pressure (BP) and heart rate (HR) of these patients were monitored continuously. The outcome assessors were blinded. The results of the TT were positive in 13 (65%) of the patients in the control groups and in two (10%) of the patients with compression (P < 0.0001). Throughout the test, the systolic BP was not different among the groups. On the other hand, the HR measures showed a difference only in the tilted position at 2 minutes, of 73 ± 16 beats per minute (bpm) in the control group and of 69 ± 16 bpm (P = 0.047) in the compression group.

CONCLUSION

Compression of the lower limbs is very effective to render the TT negative in patients with a diagnosis of VS.

Drugs and pacemakers for vasovagal, carotid sinus and situational syncope

BACKGROUND

Neurally mediated reflex syncope is the most common cause of transient loss of consciousness. In patients not responding to non-pharmacological treatment, pharmacological or pacemaker treatment might be considered.

OBJECTIVES

To examine the effects of pharmacological therapy and pacemaker implantation in patients with vasovagal syncope, carotid sinus syncope and situational syncope.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) on The Cochrane Library (Issue 1, 2008), PubMed (1950 until February 2008), EMBASE on OVID (1980 until February 2008) and CINAHL on EBSCOhost (1937 until February 2008). No language restrictions were applied.

SELECTION CRITERIA

We included parallel randomized controlled trials and randomized cross-over trials of pharmacological treatment (beta-blockers, fludrocortisone, alpha-adrenergic agonists, selective serotonine reuptake inhibitors, ACE inhibitors, disopyramide, anticholinergic agents or salt tablets) or dual chamber pacemaker treatment. Studies were included if pharmacological or pacemaker treatment was compared with any form of standardised control treatment (standard treatment), placebo treatment, or (other) pharmacological or pacemaker treatment. We did not include non-randomized studies.

DATA COLLECTION AND ANALYSIS

Two reviewers independently assessed the risk of bias. Using a standardised data extraction form, they extracted characteristics and results of the various studies. In a consensus meeting they discussed any disagreements that had occurred during data extraction. If no agreement could be reached, a third reviewer was asked to make a decision. Summary estimates with 95% confidence intervals of treatment effect were calculated using relative risks, rate ratios or weighted means differences depending on the type of outcome reported.

MAIN RESULTS

We included 46 randomized studies, 40 on vasovagal syncope and six on carotid sinus syncope. No studies on situational syncope matched the criteria for inclusion in our review. Studies in general were small with a median sample size of 42. A wide range of control treatments were used with 22 studies using a placebo arm. Blinding of patients and treating physicians was applied in eight studies. Results varied considerably between studies and between types of outcomes.For vasovagal syncope, the occurrence of syncope upon provocational head-up tilt testing was lower upon treatment with beta-blockers, ACE-inhibitors and anticholinergic agents compared to standard treatment. For carotid sinus syncope, the occurrence of syncope upon carotid sinus massage was lower on midodrine treatment compared to placebo treatment in one study.

AUTHORS' CONCLUSIONS

There is insufficient evidence to support the use of any of the pharmacological or pacemaker treatments for vasovagal syncope and carotid sinus syncope. Larger studies using patient relevant outcomes are needed.

Syncope in children and adolescents: Evaluation and treatment

Syncope in children is most often neurally mediated and usually has a natural history of spontaneous resolution or improvement. Syncope is defined as the temporary loss of consciousness resulting from a reversible disturbance of cerebral function. It is characterized by a loss of consciousness due to a lack of cerebral blood flow, rapid or sudden onset, falling of the patient, if not supported, and transiency of the attack. In children, it is most often benign, but may sometimes herald a more serious, potentially life-threatening cause. The main purpose of the present paper is to propose an evaluation scheme that will allow the physician involved in the care of children to differentiate the life-threatening causes of syncope with potential for injury or sudden death from the common, more benign neurally mediated syncope. Secondarily, the present article facilitates the identification of the patient with neurally mediated syncope who may benefit from medical therapy and distinguishes syncope from the more frequent noncardiac 'spells' of childhood.

Application of head-up tilt table testing in children

BACKGROUND/PURPOSE

We investigated the application of head-up tilt table testing (HUT) and management of neurocardiogenic syncope (NCS) in children, as pediatric studies are limited.

METHODS

Seventy-nine patients (ages 6-18 years) underwent HUT for evaluation of syncope. Patient triggers and premonitory symptoms allowed the clinical diagnosis of NCS or non-NCS. Results were divided into four hemodynamic types (1, 2A, 2B, and 3) according to patient response to HUT.

RESULTS

NCS occurred in 65 patients and non-NCS in 14 patients. Isoproterenol infusion significantly increased the sensitivity of the test (from 28% to 45%) and was associated with a slight decrease in the specificity (from 93% to 86%). Subjects in the type 1 group accounted for the majority of responses to the test (69%). There were no complications associated with the test. At follow-up (16.6 ± 9.3 months), the overall recurrence rate was 30.8% but NCS was less severe in most patients. The recurrence rate was similar for patients with a positive or negative HUT and for both pharmacologically and non-pharmacologically treated patients.

CONCLUSION

HUT can be safely performed with a high specificity in children, with the sensitivity of HUT improved by isoproterenol. Therefore, a positive response to treatment is reassuring to the physician and family. NCS is generally a self-limited condition despite a high recurrence rate.

alpha-Adrenoceptor agonists for the treatment of vasovagal syncope: a meta-analysis of worldwide published data

AIM

The present study was aimed at evaluating present randomized controlled trials (RCTs) regarding the effect of alpha-adrenoceptor agonists on vasovagal syncope (VVS).

METHODS

According to inclusion and exclusion criteria, articles were selected from medical electronic databases. RCTs were then assessed based on the Juni assessment, and meta-analysis was completed using the Review Manager 4.2 software. Indication to further evaluate effects was the recurrence of syncope during follow-up treatment or a response in the head-up tilt test (HUT) after treatment. The results were stated as odd ratio (OR), with a 95% confidence interval (CI) and a p < 0.05 significant level.

RESULTS

In total, six RCTs were selected. Funnel plot analysis showed possible publication bias. Meta-analysis of the six RCTs, including all 165 patients in the treatment group and 164 patients in the control group, indicated that alpha-adrenoceptor agonists were more effective than placebos in treating VVS (OR = 0.21, 95% CI: 0.06-0.77, p = 0.02). The further, weighted independent t-test disclosed that the weighted mean percentage of responders for midodrine (76.3%+/- 7.7%) was significantly higher than that for etilefrine (65.5%+/- 15.4%) (t = 5.863, p < 0.001).

CONCLUSION

The currently published RCTs support that alpha-adrenoceptor agonists might be effective for VVS. Midodrine can be regarded as a better choice compared with etilefrine.

Neurological aspects of syncope and orthostatic intolerance

Sudden falling with loss of consciousness from syncope and symptoms of orthostatic intolerance are common, dramatic clinical problems of diverse cause, but cerebral hypoperfusion is the ultimate mechanism in most. Cardiac, reflex, and orthostatic hypotension are important forms to consider. Syncope must be differentiated from seizures, psychiatric events, drop attacks, and other mimics. However, factors such as syncopal induced movements, ictal bradycardia, and insufficient clinical information can confound accurate diagnosis and hamper appropriate treatment. Progress in the diagnosis, treatment, and understanding of underlying mechanisms is continually advancing.

The role of tilt training in preventing recurrent syncope in patients with vasovagal syncope: a prospective and randomized study

BACKGROUND

Recurrent vasovagal syncope (VVS) can be a severely disabling disorder that may lead to an important deterioration of quality of life because of the severity and recurrence of episodes. This study sought to investigate the effectiveness of repeated orthostatic self-training in preventing syncope in patients with recurrent VVS.

METHODS

Eighty-two consecutive patients (mean age 41 +/- 4 years, 37 males) with recurrent VVS episodes and positive head-up tilt testing (HUT) were enrolled in this study. The patients were then randomized (1:1) to conventional therapy or conventional therapy plus additional tilt training sessions. The patients were followed for spontaneous syncope for one year. Primary end-points were the recurrence of syncope, the number of episodes, and the interval of time to the first recurrence.

RESULTS

There were no significant differences of baseline clinical characteristics and parameters of HUT between the tilt training and control groups. The patients had 4 +/- 2/year syncopal episodes prior to the HUT. The mean follow-up after randomization was 12 +/- 2 months. Spontaneous syncope recurrence during follow-up was 56% (23 patients) versus 37% (15 patients) in the control and tilt training groups, respectively (P = 0.1). Time to first recurrence was also similar in both groups (70 +/- 20 days vs 50 +/- 15 days, P = 0.09). The frequency of recurrent syncopes was similar in all types of VVSs while the rate of episodes was significantly higher in control group in patients with vasodepressor type during follow-up period (32% vs 10%, P = 0.04). The mean number of recurrent syncope episodes was also similar in both groups (3 +/- 1 vs 2 +/- 1, P = 0.4).

CONCLUSIONS

Tilt training was unable to influence the spontaneous syncope recurrence for recurrent VVS except for vasodepressor type.

Pathophysiology, diagnosis, and treatment of orthostatic hypotension and vasovagal syncope

Orthostatic hypotension (OH) occurs in 0.5% of individuals and as many as 7-17% of patients in acute care settings. Moreover, OH may be more prevalent in the elderly due to the increased use of vasoactive medications and the concomitant decrease in physiologic function, such as baroreceptor sensitivity. OH may result in the genesis of a presyncopal state or result in syncope. OH is defined as a reduction of systolic blood pressure (SBP) of at least 20 mm Hg or diastolic blood pressure (DBP) of at least 10 mm Hg within 3 minutes of standing. A review of symptoms, and measurement of supine and standing BP with appropriate clinical tests should narrow the differential diagnosis and the cause of OH. The fall in BP seen in OH results from the inability of the autonomic nervous system (ANS) to achieve adequate venous return and appropriate vasoconstriction sufficient to maintain BP. An evaluation of patients with OH should consider hypovolemia, removal of offending medications, primary autonomic disorders, secondary autonomic disorders, and vasovagal syncope, the most common cause of syncope. Although further research is necessary to rectify the disease process responsible for OH, patients suffering from this disorder can effectively be treated with a combination of nonpharmacologic treatment, pharmacologic treatment, and patient education. Agents such as fludrocortisone, midodrine, and selective serotonin reuptake inhibitors have shown promising results. Treatment for recurrent vasovagal syncope includes increased salt and water intake and various drug treatments, most of which are still under investigation.

Current treatment of recurrent vasovagal syncope: between evidence-based therapy and common sense

Vasovagal syncope is very frequent and benign and the vast majority of subjects do not need any specific treatment, but only reassurance and education. An unknown but small percentage of patients require specific treatment when syncope is very frequent or is responsible for major trauma. For these patients, there are some evidence-based therapies available and some first-line treatments appear to be established. The therapeutic choice mainly depends on the presence and duration of prodromal symptoms. In subjects aged < 70 years with well recognizable prodromes, the first-line treatment is counterpressure manoeuvres. In patients with no or minimal prodromes, but with tilt testing and carotid sinus massage (CSM) both positive, cardiac pacing appear to be the first-line therapy. However, an area of uncertainty remains, represented by patients with no or minimal prodromes and negative CSM. For these patients, appropriate treatment (drugs, tilt training, cardiac pacing, relaxation-based treatment) can be chosen by considering the clinical context, the risk of trauma and possible comorbidities, in addition to utilizing the little or controversial knowledge available, as well as common sense.

Basic autonomic nervous function in patients with neurocardiogenic syncope

Basic autonomic nervous function was evaluated in patients with neurocardiogenic syncope (NCS). Atropine, isoproterenol, propranolol, phenylephrine, and phentolamine were administered successively, and parasympathetic nerve activity and beta- (and alpha-) activity, sensitivity, and secretion of the sympathetic nerve were determined in patients with NCS and control subjects. In patients with NCS, beta- and alpha- sensitivity were higher and beta-activity and beta- and alpha-secretion lower than in control subjects. In patients with NCS, the increased basic beta-sensitivity may contribute to induce strong cardiac contractions and augment ventricular mechanoreceptor response, and a compensatory state against diminished neuronal sympathetic activity is suggested by the increased alpha-sensitivity.

Withdrawal of fall-risk-increasing drugs in older persons: effect on tilt-table test outcomes

OBJECTIVES

To determine whether outcomes of tilt-table tests improved after withdrawal of fall-risk-increasing drugs (FRIDs).

DESIGN

Prospective cohort study.

SETTING

Geriatric outpatient clinic.

PARTICIPANTS

Two hundred eleven new, consecutive outpatients, recruited from April 2003 until December 2004.

MEASUREMENTS

Tilt-table testing was performed on all participants at baseline. Subsequently, FRIDs were withdrawn in all fallers in whom it was safely possible. At a mean follow-up of 6.7 months, tilt-table testing was repeated in 137 participants. Tilt-table testing addressed carotid sinus hypersensitivity (CSH), orthostatic hypotension (OH), and vasovagal collapse (VVC). Odds ratios (ORs) of tilt-table-test normalization according to withdrawal (discontinuation or dose reduction) of FRIDs were calculated using multivariate logistic regression analysis.

RESULTS

After adjustment for confounders, the reduction of abnormal test outcomes (ORs) according to overall FRID withdrawal was 0.34 (95% confidence interval (CI)=0.06-1.86) for CSH, 0.35 (95% CI=0.13-0.99) for OH, and 0.27 (95% CI=0.02-3.31) for VVC. For the subgroup of cardiovascular FRIDs, the adjusted OR was 0.13 (95% CI=0.03-0.59) for CSH, 0.44 (95% CI=0.18-1.0) for OH, and 0.21 (95% CI=0.03-1.51) for VVC.

CONCLUSION

OH improved significantly after withdrawal of FRIDs. Subgroup analysis of cardiovascular FRID withdrawal showed a significant reduction in OH and CSH. These results imply that FRID withdrawal can cause substantial improvement in cardiovascular homeostasis. Derangement of cardiovascular homeostasis may be an important mechanism by which FRID use results in falls.

Current management of syncope : focus on drug therapy

Syncope is defined as transient loss of consciousness as a result of inadequate cerebral perfusion. The causes of syncope fall into five broad categories: neurally mediated, orthostatic (the most frequent causes), cardiac arrhythmias, structural cardiovascular (relatively uncommon cause), and cerebrovascular (very rare). The initial evaluation of the syncope patient includes a detailed medical history and physical exam, and usually an ECG and echocardiogram. Thereafter, selected additional testing (e.g. ambulatory ECG recording, autonomic function testing, electrophysiologic study) may be needed on a case-by-case basis. Neurally mediated and orthostatic syncope should first be treated by conservative therapies including hydration/volume expanders and physical counter-maneuvers. Various drugs may play a role as second-line of treatment. However, apart from midodrine, randomized studies of drug therapy are largely lacking, and most agents have not proved to be predictably effective. For syncope due to cardiac arrhythmias, treatment options (depending on the specific circumstance) include ablation of the arrhythmia origin, antiarrhythmic drugs, and/or implantable devices (pacemakers and defibrillators). In the case of syncope due to structural cardiovascular defects (e.g. acute myocardial ischemia, pulmonary hypertension, obstructive cardiomyopathy), treatment is aimed at ameliorating the underlying structural defect. In brief, establishing a specific cause(s) for syncope is crucial. Only then can a potentially effective treatment strategy be contemplated.

Neurocardiogenic syncope: latest pharmacological therapies

Neurocardiogenic syncope is a neurally mediated disorder and is a common cause of syncope. The goal of treatment is to prevent recurrences with the aim of improving quality of life and reducing morbidity. Reassurance, in some cases, may suffice. In others, augmenting central blood volume by increasing fluid and/or salt intake is effective. The role of non-pharmacological physical manoeuvres is increasingly recognised, given the increasing clinical trial data supporting their efficacy. This review summarises the clinical evidence for a variety of pharmacological agents. Of these, midodrine appears to have yielded the most consistent favourable outcome. Its use, however, should be reserved for patients with recurrent and refractory syncope.

Síncope en el adolescente. Orientación diagnóstica y terapéutica

Syncopal episodes are frequent in adolescence. Syncope is usually a benign, self-limiting condition but it may be a warning sign of serious disease that must be diagnosed and appropriately treated. The present article provides a review of the basic principles of the differential diagnosis of syncope in the adolescent patient and treatment recommendations.

Management of syncope in pediatric patients

Syncope is a common symptom in children, particularly in the teenage years. Although most often benign, it can be a symptom of serious underlying conditions and may result in sudden death. It is estimated that approximately 1% to 2% of children presenting with syncope have a serious underlying disorder. Therefore, it is important to assess patients logically and be able to separate those with serious pathology from those without. A good history is the most important step in this regard, and can save a significant amount of anxiety, time, and money for the patient and for the health care system. Most patients can be determined to have vasovagal syncope on the basis of a good history, physical examination, and standard electrocardiogram. Other tests, such as echocardiography and electrocardiogram monitoring (eg, Holter/event monitors, including implantable event monitors), may be reserved for those with abnormalities in the initial workup. Therapy depends on the underlying disorder. Vasovagal syncope may only need reassurance and volume loading with increase in salt and water intake.

Hemodynamic significance of heart rate in neurally mediated syncope

BACKGROUND

Vasovagal and vasodepressor syncope are used interchangeably in the literature to describe the common faint syndrome, now collectively named neurally mediated syncope. The significance of heart rate (HR) in these reflex-induced reactions remains unclear.

HYPOTHESIS

The study was undertaken to investigate the hemodynamic significance of HR in tilt-induced neurally mediated syncope.

METHODS

In all, 113 patients with syncope of unknown etiology were studied by head-up tilt test with invasive hemodynamic monitoring. Thirty-five patients (15 women, 20 men, age range 21 to 72 years) developed syncope and were enrolled for analysis. The hemodynamic data were compared between patients who developed bradycardia (vasovagal group, n = 15) and those without bradycardia (vasodepressor group, n = 20).

RESULTS

The baseline hemodynamic data (mean +/- standard deviation) and the hemodynamic responses after 10-min headup tilt were similar between patients in the vasovagal and vasodepressor groups. During syncope, patients with vasovagal reaction developed hypotension and paradoxical bradycardia (HR = 52.4 +/- 5.9 beats/min), while patients with vasodepressor reaction developed a precipitous drop in arterial blood pressure with inappropriate HR (105 +/- 21 beats/min) compensation. Patients with vasovagal syncope manifested a significantly lower cardiac index and a significantly higher systemic vascular resistance index than patients with vasodepressor syncope (1.47 +/- 0.29 vs. 1.97 +/- 0.41 1/min/m2, p < 0.001 and 2098 +/- 615 vs. 1573 +/- 353 dynes x s x cm(-5) x m2, p < 0.003, respectively). A positive correlation existed between HR and cardiac index (r = 0.44, p = 0.008) during syncope in the patients studied.

CONCLUSIONS

These findings suggest that the hemodynamic characteristics of vasovagal and vasodepressor reactions are different, and that HR plays a significant role in neurally mediated syncope.

A patient responding to combined therapy with pirmenol and midodrine for refractory neurally mediated syncope complicated by prostatic hypertrophy

A 67-year-old man with neurally mediated syncope (NMS) complicated by prostatic hypertrophy responded well to combined therapy with pirmenol and midodrine. In 2003, syncope occurred while the patient was driving a car. Results of head-up tilt-table testing (HUT) suggested a mixed type of NMS. Oral administration of disopyramide provided severe urinary obstruction. Pirmenol treatment was not associated with syncope during ordinary HUT, but nausea, sweating, and syncope occurred during HUT with provocative administration of isosorbide dinitrate. Combined therapy with pirmenol and midodrine avoided syncope during HUT, and has prevented attacks since discharge from the hospital.

Tilt training for recurrent neurocardiogenic syncope: effectiveness, patient compliance, and scheduling the frequency of training sessions

Unsatisfactory results obtained with medical therapy and dual-chamber pacing for prevention of recurrent neurocardiogenic syncope necessitated the development of new treatment modalities. Tilt-training, a novel treatment for recurrent neurocardiogenic syncope based on exercise sessions with prolonged upright posture (either on a tilt-table or standing on foot against a wall), was shown to be effective in preventing the recurrence of neurocardiogenic syncope. The purpose of this study was to demonstrate the long-term beneficial effects of a transient tilt training program lasting 2 months. Thirty-two patients with recurrent neurocardiogenic syncope (mean number of syncope episodes in the last 6 months was 3.4 +/- 2.3) constituted the study group. All of the patients were tilt test positive. The patients were taught a tilt training program with 2 phases (in-hospital training with repeated tilt procedures until 3 consecutive negative results were obtained and home exercises with standing against a wall) and home exercises lasted a maximum of 2 months. After this training program, the patients received no treatment and were followed for the recurrence of syncope. At the end of the follow-up period (376 +/- 45 days), 81% of the patients were free of recurrent syncope. This study revealed that similar successful results can also be obtained with a transient tilt training program as a first line treatment strategy. Less interference with the daily activities of the patients is the major advantage of this strategy. The ease of performance and high effectiveness rate will most likely result in more frequent utilization of this treatment modality.