Permanent cardiac pacing versus medical treatment for the prevention of recurrent vasovagal syncope: a multicenter, randomized, controlled trial

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.

Why is the Tilt Table Test Still Useful to Define who Should or Should Not Get A Pacemaker with Vasovagal Syncope?

The the tilt table test (TTT )has been used identify appropriate candidates for pacing in the majority of randomized trials. However, in recent years, it has been claimed-based largely on International Study on Syncope of Uncertain Etiology (ISSUE) studies-that the TTT demonstrates only a weak correlation with the mechanism documented by implantable loop recorder (ILR) at the time of syncope and thus confounds the correct diagnosis. Thus, cardiac pacing was supported in patients with recurrent vasovagal syncope (VVS) in whom clinically relevant asystole had been documented by ILR. In the present Editorial, we tried to discuss potential role of TTT in diagnostic workflow of VVS based on current data.

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.

Permanent pacemaker implantation in unexplained syncope patients with borderline sinus bradycardia and electrophysiology study-proven sinus node disease

BACKGROUND

Significant sinus bradycardia (SB) in the context of sinus node dysfunction (SND) has been associated with neurological symptoms. The objective was to evaluate the effect of permanent pacing on the incidence of syncope in patients with rather mild degrees of SB, unexplained syncope, and "positive" invasive electrophysiologic testing.

METHODS

This was an observational study based on a prospective registry of 122 consecutive mild SB patients (61.90 ± 18.28 years, 61.5% male, 57.88 ± 7.73 bpm) presenting with recurrent unexplained pre and syncope attacks admitted to our hospital for invasive electrophysiology study (EPS). Τhe implantation of a permanent antibradycardia pacemaker (ABP) was offered to all patients according to the results of the EPS. Eighty patients received the ABP, while 42 denied.

RESULTS

The mean of reported syncope episodes was 2.23 ± 1.29 (or presyncope 2.36 ± 1.20) in the last 12 months before they were referred for a combined EP guided diagnostic and therapeutic approach. Over a mean follow-up of approximately 4 years (50.39 ± 32.40 months), the primary outcome event (syncope) occurred in 18 of 122 patients (14.8%), 6 of 80 (7.5%) in the ABP group as compared to 12 of 42 (28.6%) in the no pacemaker group (P = .002).

CONCLUSIONS

Among patients with mild degree of SB and a history of unexplained syncope, a set of positivity criteria for the presence of EPS defined SND after differentiating reflex syncope, identifies a subset of patients who will benefit from permanent pacing.

Permanent pacing for recurrent vasovagal syncope: New answers or just more questions?

Vasovagal syncope (VVS) is a clinical condition related to bradycardia (cardioinhibitory response) and/or hypotension (vasodepressor response), likely mediated by parasympathetic overactivity and sympathetic withdrawal. Although clinical presentation is usually related to a self-limited event, frequent episodes or events without prodrome might be debilitating. There are limited medical therapies proven effective in randomized clinical trials. In patients not responsive to standard therapy, permanent pacemaker therapy may be suggested. However, the role of cardiac pacing for the prevention of syncope recurrences remains controversial due to difficulties to exclude potential role of the vasodepressor component during the episode.

New insights in diagnostics and therapies in syncope: a novel approach to non-cardiac syncope

This article aims to give advice on how to identify and manage patients with syncope who are at risk of severe outcomes, that is, at risk of trauma, potentially life-threatening episodes or frequent recurrences reducing quality of life. The first step of syncope diagnostic assessment is to identify patients with cardiac syncope, and once established, these patients must receive the adequate mechanism-specific treatment. If cardiac syncope is unlikely, reflex (neurally mediated) syncope and orthostatic hypotension are the most frequent causes of transient loss of consciousness. For these presentations, efficacy of therapy is largely determined by the mechanism of syncope rather than its aetiology or clinical features. The identified mechanism of syncope should be carefully assessed and assigned either to hypotensive or bradycardic phenotype, which will determine the choice of therapy (counteracting hypotension or counteracting bradycardia). The results of recent trials indicate that 'mechanism-specific therapy' is highly effective in preventing recurrences. Established mechanism-specific treatment strategies include withdrawal of hypotensive drugs, applying fludrocortisone and midodrine for the hypotensive phenotype and cardiac pacing in the bradycardic phenotype.

Pacing Therapies for Vasovagal Syncope

Vasovagal Syncope (VVS) is mediated by a cardiac autonomic reflex with resultant bradycardia and hypotension, precipitating syncope. While benign and mostly well controlled, recurrent VVS can be debilitating and warrants intervention. Non-pharmacological management of VVS have had variable success. In patients with recurrent cardioinhibitory VVS, permanent pacing can be effective. The utility of pacing to preempt the syncopal depends on the prominent temporal role of bradycardia during the vasovagal reflex. Current guidelines recommend pacing as a therapy to consider in older patients with recurrent VVS. Although younger patients can benefit, one should be cautious given the long-term risk of complications. Available data appears to favor a dual chamber pacemaker with closed loop stimulation algorithm to prevent recurrent cardioinhibitory VVS. Several aspects, including mechanistic understanding of VVS and appropriate patient selection, remain unclear, and require further study.

Recurrent seizures in a young woman: when video-EEG diagnoses a cardiac cause: a case report

Background

While transient loss of consciousness is a frequent presenting symptom, differential diagnosis between syncope and epilepsy can be challenging. Misdiagnosis of epilepsy leads to important psychosocial consequences and eliminates the opportunity to treat patient’s true condition.

Case summary

A 39-year-old woman presenting with recurrent seizures since her childhood was referred to neurological consultation. Electroencephalograms (EEGs) and magnetic resonance imaging previously performed were normal. A sleep-deprived video-EEG was performed and highlighted after 12 h of sleep deprivation a progressive dropping of the heart rate followed by a complete heart block without ventricular escape rhythm and asystole for about 30 s. Her EEG recording later showed diffuse slow waves traducing a global cerebral dysfunction and suffering. The diagnosis of vaso-vagal syncope with predominant cardioinhibitory response was made and a dual-chamber pacemaker with rate-drop response algorithm was implanted. After a 2 years of follow-up, the patient remained free of syncope.

Discussion

Patients presenting with loss of consciousness and convulsion are often diagnosed with epilepsy despite normal EEGs. In patients presenting with recurrent seizures with unclear diagnosis of epilepsy or in a situation of drug-resistant epilepsy, syncope diagnosis should always be considered and a risk stratification is necessary. The benefit of pacemaker implantation in patients with recurrent vaso-vagal syncope is still very controversial. Only patients presenting with spontaneous asystole should be considered for pacemaker implantation in case of recurrent vaso-vagal syncope.

Safety and efficacy of leadless pacemaker for cardioinhibitory vasovagal syncope

BACKGROUND

Single-chamber leadless pacemakers (LPs) have been shown to be an effective alternative to conventional transvenous pacemakers (CTPs), but their benefit in the context of cardioinhibitory vasovagal syncope (CI-VVS) is unknown.

OBJECTIVE

The purpose of this study was to evaluate the safety and efficacy of LP compared with dual-chamber CTP for CI-VVS.

METHODS

We conducted a multicenter, retrospective study comparing patients who received LP or dual-chamber CTP for drug-refractory CI-VVS. CI-VVS was diagnosed clinically and supported by cardiac monitoring and head-up tilt table testing. The primary efficacy endpoint was freedom from syncope during follow-up. Secondary endpoints included device efficacy and safety estimated by device-related major and minor adverse events (AEs).

RESULTS

Seventy-two patients (24 LP, 48 CTP; age 32 ± 5.5 years; 90% female; syncope frequency 7.6 ± 3.4 per year) were included. At 1 year, 91% of patients (22/24) in the LP group and 94% of patients (43/48) in the CTP group met the primary efficacy endpoint (P = .7). Device efficacy endpoint was met in 92% of the LP group and 98% of the CTP group (P = .2). Early major AEs occurred in 2 of 24 in the LP group and 3 of 48 in the CTP group (P = .4). Late major AEs occurred in 0 of 24 in the LP group and 2 of 48 in the CTP group (P = 1).

CONCLUSION

In patients with CI-VVS, single-chamber LP demonstrated equivalent efficacy in reducing syncopal events compared to dual-chamber CTP, with a similar safety profile.

Neuro-arrhythmology: a challenging field of action and research: a review from the Task Force of Neuro-arrhythmology of Italian Association of Arrhythmias and Cardiac Pacing

: There is a growing interest in the study of the mechanisms of heart and brain interactions with the aim to improve the management of high-impact cardiac rhythm disorders, first of all atrial fibrillation. However, there are several topics to which the scientific interests of cardiologists and neurologists converge constituting the basis for enhancing the development of neuro-arrhythmology. This multidisciplinary field should cover a wide spectrum of diseases, even beyond the classical framework corresponding to stroke and atrial fibrillation and include the complex issues of seizures as well as loss of consciousness and syncope. The implications of a more focused interaction between neurologists and cardiologists in the field of neuro-arrhythmology should include in perspective the institution of research networks specifically devoted to investigate 'from bench to bedside' the complex pathophysiological links of the abovementioned diseases, with involvement of scientists in the field of biochemistry, genetics, molecular medicine, physiology, pathology and bioengineering. An investment in the field could have important implications in the perspectives of a more personalized approach to patients and diseases, in the context of 'precision'medicine. Large datasets and electronic medical records, with the approach typical of 'big data' could enhance the possibility of new findings with potentially important clinical implications. Finally, the interaction between neurologists and cardiologists involved in arrythmia management should have some organizational implications, with new models of healthcare delivery based on multidisciplinary assistance, similarly to that applied in the case of syncope units.

Pacing in vasovagal syncope: Physiology, pacemaker sensors, and recent clinical trials-Precise patient selection and measurable benefit

The role of pacing in vasovagal syncope (VVS) is considered from a physiological basis. Most VVS patients lose consciousness due to hypotension before severe bradycardia/asystole occurs. Patients who benefit from dual-chamber pacing typically are older with highly symptomatic, late-onset, frequent and severe syncope with short/no prodrome and documented severe cardioinhibition. Tilt testing is of value in patients with recurrent unexplained syncope to identify important hypotensive susceptibility stemming from reduced venous return and stroke volume (SV). A negative tilt test in vasovagal patients with spontaneous asystole documented by an implantable/insertable loop recorder is associated with lower syncope recurrence rates after pacemaker implantation. Pacing may be more effective if triggered by sensor detection of a parameter changing earlier in the reflex than bradycardia when SV may still be relatively preserved. In this regard, detection of right ventricular impedance offers promise. Conservatism is recommended, limiting pacing in VVS to a small subset of symptomatic older patients with clearly documented cardioinhibition and paying particular attention to the timing of loss of consciousness in relation to asystole/bradycardia. Understanding VVS physiology permits application of well-timed, appropriate pacing that yields benefit for highly symptomatic patients.

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.

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.

Pacing for Vasovagal Syncope

Vasovagal syncope (VVS) is due to a common autonomic reflex involving the cardiovascular system. It is associated with bradycardia (cardioinhibitory response) and/or hypotension (vasodepressor response), likely mediated by parasympathetic activation and sympathetic inhibition. While generally a situational, isolated and/or self-limited event, for some, VVS is recurrent, unpredictable and debilitating. Conservative, non-pharmacological management may help, but no specific medical therapy has been proven widely effective. Permanent pacing may have specific benefit, but its value has been debated. The temporal causative association of bradycardia with syncope in those with VVS may help identify which patient could benefit from pacing but the timing and type of pacing in lieu of blood pressure changes may be critical. The mode, rate, pacing algorithm and time to initiate dual-chamber pacing preferentially with respect to the vasovagal reflex may be important to prevent or ameliorate the faint but completely convincing data are not yet available. Based on available data, DDD pacing with the closed loop stimulation algorithm appears a viable, if not the best, alternative presently to prevent recurrent VVS episodes. While several knowledge gaps remain, permanent pacing appears to have a role in managing select patients with VVS.

Pacing in neurocardiogenic/vasovagal syncope

Pacing for neurocardiogenic or vasovagal syncope (VVS) has been practised for five decades, but the 1986 advent of tilt testing provided a means of diagnosis frequently revealing, in the early days, asystole caused by VVS. This was the basis for pacing these patients and the first studies created enthusiasm followed by randomised controlled trials, which were imperfectly designed, "confirming" benefit. When better trial design was employed, there was no obvious benefit. However, some cardiologists had seen patients experience a huge positive difference with pacing, so they set out to identify them. Two studies using ECG loop recorders to document heart rhythm during spontaneous attacks allowed better patient selection for pacing and appeared to achieve the aim. Further, it was noted in the second study, a randomised controlled trial (RCT) with good design, that tilt testing added a further dimension to the identification of the patient who would benefit. Thus, loop recorders are used to show asystole in spontaneous attacks and when tilt testing is negative, implying a lesser vasodepressor component, the patient will have the best outcome. From the available evidence, pacing should be dual-chamber in older patients (>40 years) with severe symptoms and in whom standard measures have demonstrably failed. The method of triggering pacing and its timing of introduction have not yet been resolved. Today's method is rate-hysteresis but there is another sensed event as an alternative: right ventricular impedance, which is now in RCT with substantial pilot evidence in its favour.

Should we treat severe vasovagal syncope with a pacemaker?

Cardiac pacing for vasovagal syncope (VVS) addresses the cardioinhibitory component of the reflex but cannot directly affect vasodepression, which occurs in every reflex even when hidden by dominant cardioinhibition. The randomized controlled trials of pacing in VVS have, after almost 2 decades, determined that a small number of patients can benefit because their vasodepressor component is not severe. Early studies compared pacing with no therapy yielding highly significant benefits. Subsequently, all study patients had implanted devices with half being switched off. No benefit was seen. The ISSUE-3 study found significant benefit (P < 0.039) in prevention of syncope recurrence in older patients. A sub-study later showed those with negative tilt tests, otherwise indistinguishable from tilt-positives, had 5% recurrence in 21 months (P < 0.004). There is acceptance that pacing must be dual chamber, but the question of how pacing is delivered remains open. Relying on falling heart rate is insufficient, probably because it occurs too late. Other algorithms which indirectly detect neuroendocrine changes earlier than heart rate fall may have useful application. In clinical terms, the patient to be considered for pacing should not be young and have severe symptoms. Ideally, tilt testing should be negative implying vasodepression of lesser severity and, therefore, yielding fewer syncope recurrences. When selecting pacing, additional concern must be given to regression to the mean of symptoms, severe to less severe. Patients seek help when they are at their worst. Moreover, many years of pacing are unlikely to be free of complications related to implanted hardware.

Reflex syncope: Diagnosis and treatment

For the diagnosis of reflex syncope, diligent history-building with the patient and a witness is required. In the Emergency Department (ED), the assessment of syncope is a challenge which may be addressed by an ED Observation Unit or by a referral to a Syncope Unit. Hospital admission is necessary for those with life-threatening cardiac conditions although risk stratification remains an unsolved problem. Other patients may be investigated with less urgency by carotid sinus massage (>40 years), tilt testing, and electrocardiogram loop recorder insertion resulting in a clear cause for syncope. Management includes, in general terms, patient education, avoidance of circumstances in which syncope is likely, increase in fluid and salt consumption, and physical counter-pressure maneuvers. In older patients, those that will benefit from cardiac pacing are now well defined. In all patients, the benefit of drug therapy is often disappointing and there remains no ideal drug. A role for catheter ablation may emerge for the highly symptomatic reflex syncope patient.

Benefit of dual-chamber pacing with Closed Loop Stimulation in tilt-induced cardio-inhibitory reflex syncope (BIOSync trial): study protocol for a randomized controlled trial

Background

The efficacy of dual-chamber cardiac pacing in neuro-mediated reflex syncope with a cardio-inhibitory response to the Tilt-Table test (TT) has not been definitively assessed so far. The lack of reproducibility of results from previous studies may be partially explained by discrepancies in subject selection and some weaknesses in design and methods. The European Society of Cardiology (ESC) has set a class IIb indication to pacemaker implantation in this population recommending further research.

Methods/design

The BIOSync study is a multicenter, patient- and outcome-assessor-blind, randomized, parallel-arm, placebo-controlled trial with the objective of assessing the clinical benefit of cardiac pacing in patients with frequently recurrent reflex syncope, suspected (but not proven) to be triggered by asystolic pauses as showing a VASIS 2B response to the TT (>3-s pause regardless of blood pressure drop). The primary and secondary endpoints are time to first post-implantation recurrence of syncope or the combination of pre-syncope or syncope, respectively. One hundred and twenty-eight consenting patients will be 1:1 randomized to dual-chamber cardiac pacing ‘on’ or ‘off’ after pacemaker implantation, and followed up until the first adjudicated primary endpoint event for a maximum of 2 years. The so-called Closed Loop Stimulation function on top of dual-chamber pacing is the pacing mode selected in the study active arm. Participating patients are asked to self-report syncopal symptoms at least every 3 months with self-administered questionnaires addressed to an independent Adjudication Committee. Patients and members of the Adjudicating Committee are blinded to randomization. The study is designed to detect a 40% relative reduction in the 2-year incidence of syncopal recurrences with 80% statistical power.

Discussion

The BIOSync study is designed to definitively assess the benefit of pacing against placebo in reflex syncope patients with a cardio-inhibitory response to the TT. The study will also provide important information on the efficiency of the TT in appropriately selecting reflex syncope patients for cardiac pacing.

Trial registration

ClinicalTrials.gov, identifier: NCT02324920 (27 October 2016, date last accessed).

Electronic supplementary material

The online version of this article (doi:10.1186/s13063-017-1941-4) contains supplementary material, which is available to authorized users.

The Current Indication for Pacemaker in Patients with Cardioinhibitory Vasovagal Syncope

The most frequent cause of syncope is vasovagal reflex. It is associated with worse quality of life, depression, fatigue and physical injury. Recurrence of vasovagal syncope is an aggravating, reaching the rate of 69%. Initial step and pharmacological treatment may not work, especially in patients with recurrent syncope without prodrome. These patients can present cardioinhibitory response with asystole. Studies were designed to analyses the effectiveness of pacemaker for prevention of syncope. In this review, nonrandomized clinical trials, open-label randomized, double-blind randomized, placebo-controlled, and studies based on tilt test or Implantable Loop Recorder findings will be discussed.

A long-term follow-up of patients with prolonged asystole of greater than 15s on head-up tilt testing

BACKGROUND

Head-up tilt (HUT) is used for diagnosis of vasovagal syncope (VVS), and can provoke cardioinhibition. VVS is usually considered benign, however pacemaker insertion may be indicated in some patients. We sought to characterize the long-term outcomes of patients with prolonged asystole (>15s) on HUT.

METHODS

We conducted a retrospective study on patients with asystole >15s on HUT identified from 5133 patients who were investigated between 1998 and 2012 at our institution. Patients were mailed questionnaires or telephoned to ascertain outcomes. Where contact was not possible, the patients' general practitioners were contacted to request up-to-date information.

RESULTS

A total of 26 patients with a mean age of 45 ± 18 years and a mean duration of asystole on HUT of 26 ± 7s were successfully followed up from a total of 77 patients identified. The follow-up duration was 99 ± 39 months. Six patients had undergone pacemaker (PPM) implantation. Of the patients without PPM, 16 reported spontaneously improved symptoms. Ten patients sustained injury prior to HUT compared with one after HUT, when a clear diagnosis was made and management advice was given. There were no major injuries or deaths after HUT. The 6 patients with PPMs had a mean age of 60 ± 16 (67% male) at HUT. Four patients had no further syncope after PPM and two demonstrated improvement but still experienced recurrent syncope.

CONCLUSIONS

Prolonged asystole (>15s) on tilt does not necessarily predict adverse outcomes with most patients improving spontaneously over the long-term. Pacemaker insertion in selected patients may reduce syncope recurrence but does not always abolish it.

Tilt-table testing of patients with pacemaker and recurrent syncope

The diagnosis of recurrent syncope in patients with pacemakers (PM) is quite challenging and the etiology of syncope is often multifactorial. To portray the mechanism of syncope in PM patients, we report the results of head-up tilt table testing (HUT) in a series of patients with PM, originally implanted for reasons other than neurally mediated syncope, referred due to syncope or pre-syncope (aborted syncope, vertigo, suspected orthostatic hypotension).

Forty-one patients with PM undergoing a HUT in our syncope unit between January 1st, 2007 and December 31st 2011 were included. A standard HUT protocol with nitroglycerine provocation was used and the test results were classified according to current guidelines. Baseline data were retrieved from the medical records.

Overall, 54% of patients had a positive response to HUT. Vasodepressor or orthostatic hypotensive response were the most prevalent responses accounting for 72% of patients with a positive test. There were no differences between groups with positive or negative test result regarding age, gender, resting blood pressure and heart rate, daily fluid intake, pacing mode, pacing indication or pacing rhythm at rest.

HUT in patients with pacemakers has a high diagnostic yield. Although, the majority of patients had a vasodepressor or orthostatic hypotensive response, cardioinhibitory response leading to syncope was also seen.

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.

Assessment of a standardized algorithm for cardiac pacing in older patients affected by severe unpredictable reflex syncopes

AIMS

Opinions differ regarding the effectiveness of cardiac pacing in patients affected by reflex syncope. We assessed a standardized guideline-based algorithm in different forms of reflex syncope.

METHODS AND RESULTS

In this prospective, multi-centre, observational study, patients aged >40 years, affected by severe unpredictable recurrent reflex syncopes, underwent carotid sinus massage (CSM), followed by tilt testing (TT) if CSM was negative, followed by implantation of an implantable loop recorder (ILR) if TT was negative. Those who had an asystolic response to one of these tests received a dual-chamber pacemaker.

POPULATION

253 patients, mean age 70 ± 12 years, median 4 (3-6) syncopes, 89% without or with short prodromes. Of these patients, 120 (47%) received a pacemaker and 106 were followed up for a mean of 13 ± 7 months: syncope recurred in 10 (9%). The recurrence rate was similar in 61 CSM+ (11%), 30 TT+ (7%), and 15 ILR+ (7%) patients. The actuarial total syncope recurrence rate was 9% (95% confidence interval (CI), 6-12) at 1 year and 15% (95% CI, 10-20) at 2 years and was significantly lower than that observed in the group of 124 patients with non-diagnostic tests who had received an ILR: i.e. 22% (95% CI, 18-26) at 1 year and 37% (95% CI, 30-43) at 2 years (P = 0.004).

CONCLUSION

About half of older patients with severe recurrent syncopes without prodromes have an asystolic reflex for which cardiac pacing goes along with a low recurrence rate. The study supports the clinical utility of the algorithm for the selection of candidates to cardiac pacing in everyday clinical practice.

CLINICAL TRIAL REGISTRATION

http://www.clinicaltrials.gov. Unique identifier: NCT01509534.

Pain-related autonomic response is modulated by the medial prefrontal cortex: An ECG-fMRI study in men

BACKGROUND

Our goal was to identify brain structures responsible for pain-related autonomic changes by the correlation of simultaneously acquired functional magnetic resonance imaging (fMRI) and electrocardiogram (ECG) data.

METHODS

Eighteen healthy men (age: 22.89 ± 1.96) were involved. Painful sensation was evoked by heat. Simultaneously recorded brain fMRI and ECG data during pain were compared to data acquired during a non-painful heat sensation. From the ECG data, time- and frequency domain parameters of heart rate variability (HRV) were extracted.

RESULTS

We found that: (1) among the common elements of both pain network and central autonomic network (CAN) only the medial prefrontal frontal cortex (MPFC) showed significant correlation with HRV; (2) the parasympathetic response to the painful stimuli showed a positive, while the sympathetic response a negative association with pain related BOLD-signal change observed in MPFC; (3) time domain parameters of HRV were negatively associated with MPFC activation.

CONCLUSIONS

The novelty of our study-compared to previous ECG-fMRI studies-is that we used pain as stimulus and investigated both frequency- and time-domain parameters of HRV. Compared to other stimuli used in earlier studies to activate the CAN, pain sensation can be standardized easier and might allow us to better understand the functional organization of CAN. The results of the current ECG-fMRI study may have direct clinical relevance in understanding the pathomechanisms of several clinical conditions.

PERSPECTIVE

There are some simultaneous ECG-fMRI and ECG-Positron Emission Tomography (PET) studies, but limited information is available about the pain-related brain function-HRV relations. The novelty of our study is that we used pain as stimulus to activate the central autonomic network and investigated both frequency- and time-domain parameters of HRV.