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Syncope can be caused by many physiological and pathophysiological conditions. Causes of syncope encompass a wide range of conditions from benign vasovagal syncope to life-threatening arrhythmias. The lack of a standardized method of evaluation and management of this large patient population leads to a wide practice variation which results in broad-based testing, frequent hospital admission and high healthcare cost. The concept of a syncope observational unit was created for inpatients and outpatients in the United States and Europe. Studies have demonstrated that syncope units, staffed by trained health care providers with sufficient resources could expedite and improve diagnostic yield, reduce hospital admission, and result in decreased healthcare cost with favorable clinical outcomes. The implementation of a standardized syncope unit has been challenging because resources and health care systems are variable regionally, nationally, and internationally. In this review, we provide an overview of the evidences that support a standardized syncope unit practice. We provide step-by-step algorithms for the "best syncope units" in the inpatient and outpatient settings by combining the synergistic experiences from the United States and Europe., (Copyright © 2022. Published by Elsevier B.V.)

Background and Objectives : Knowledge of the incidence and time frames of the adverse events of patients presenting syncope at the ED is essential for developing effective management strategies. The aim of the present study was to perform a meta-analysis of the incidence and time frames of adverse events of syncope patients. Materials and Methods : We combined individual patients' data from prospective observational studies including adult patients who presented syncope at the ED. We assessed the pooled rate of adverse events at 24 h, 72 h, 7-10 days, 1 month and 1 year after ED evaluation. Results : We included nine studies that enrolled 12,269 patients. The mean age varied between 53 and 73 years, with 42% to 57% females. The pooled rate of adverse events was 5.1% (95% CI 3.4% to 7.7%) at 24 h, 7.0% (95% CI 4.9% to 9.9%) at 72 h, 8.4% (95% CI 6.2% to 11.3%) at 7-10 days, 10.3% (95% CI 7.8% to 13.3%) at 1 month and 21.3% (95% CI 15.8% to 28.0%) at 1 year. The pooled death rate was 0.2% (95% CI 0.1% to 0.5%) at 24 h, 0.3% (95% CI 0.1% to 0.7%) at 72 h, 0.5% (95% CI 0.3% to 0.9%) at 7-10 days, 1% (95% CI 0.6% to 1.7%) at 1 month and 5.9% (95% CI 4.5% to 7.7%) at 1 year. The most common adverse event was arrhythmia, for which its rate was 3.1% (95% CI 2.0% to 4.9%) at 24 h, 4.8% (95% CI 3.5% to 6.7%) at 72 h, 5.8% (95% CI 4.2% to 7.9%) at 7-10 days, 6.9% (95% CI 5.3% to 9.1%) at 1 month and 9.9% (95% CI 5.5% to 17) at 1 year. Ventricular arrhythmia was rare. Conclusions : The risk of death or life-threatening adverse event is rare in patients presenting syncope at the ED. The most common adverse events are brady and supraventricular arrhythmias, which occur during the first 3 days. Prolonged ECG monitoring in the ED in a short stay unit with ECG monitoring facilities may, therefore, be beneficial.

Syncope is a commonly encountered and challenging problem in medical practice. Presentations are variable, and the causal mechanism often remains elusive even after extensive (and often expensive) evaluation. Clinical practice guidelines have been developed to help guide the multidisciplinary approach necessary to diagnose and manage the broad spectrum of patients presenting with syncope. The American College of Cardiology/American Heart Association, in collaboration with the Heart Rhythm Society, published its first syncope guidelines in 2017. The European Society of Cardiology released the fourth iteration of its syncope guidelines in 2018. This review highlights the differences and congruencies between the 2 sets of recommendations, their implications for clinical practice, the remaining gaps in understanding, and areas of future research., (Copyright © 2019 American College of Cardiology Foundation. All rights reserved.)

Syncope is the common clinical manifestation of different diseases, and this makes it difficult to define what outcomes should be considered in prognostic studies. The aim of this study is to critically analyze the outcomes considered in syncope studies through systematic review and expert consensus. We performed a systematic review of the literature to identify prospective studies enrolling consecutive patients presenting to the Emergency Department with syncope, with data on the characteristics and incidence of short-term outcomes. Then, the strengths and weaknesses of each outcome were discussed by international syncope experts to provide practical advice to improve future selection and assessment. 31 studies met our inclusion criteria. There is a high heterogeneity in both outcome choice and incidence between the included studies. The most commonly considered 7-day outcomes are mortality, dysrhythmias, myocardial infarction, stroke, and rehospitalisation. The most commonly considered 30-day outcomes are mortality, haemorrhage requiring blood transfusion, dysrhythmias, myocardial infarction, pacemaker or implantable defibrillator implantation, stroke, pulmonary embolism, and syncope relapse. We present a critical analysis of the pros and cons of the commonly considered outcomes, and provide possible solutions to improve their choice in ED syncope studies. We also support global initiatives to promote the standardization of patient management and data collection.

Study Objectives: There is limited evidence to guide the emergency department (ED) evaluation and management of syncope. The First International Workshop on Syncope Risk Stratification in the Emergency Department identified key research questions and methodological standards essential to advancing the science of ED-based syncope research., Methods: We recruited a multinational panel of syncope experts. A preconference survey identified research priorities, which were refined during and after the conference through an iterative review process., Results: There were 31 participants from 7 countries who represented 10 clinical and methodological specialties. High-priority research recommendations were organized around a conceptual model of ED decisionmaking for syncope, and they address definition, cohort selection, risk stratification, and management., Conclusion: We convened a multispecialty group of syncope experts to identify the most pressing knowledge gaps and defined a high-priority research agenda to improve the care of patients with syncope in the ED., (Copyright © 2014 American College of Emergency Physicians. Published by Elsevier Inc. All rights reserved.)

Background: We aimed to develop and test a literature-based model for symptoms that associate with cardiac causes of syncope., Methods and Results: Seven studies (the derivation sample) reporting ≥2 predictors of cardiac syncope were identified (4 Italian, 1 Swiss, 1 Canadian, and 1 from the United States). From these, 10 criteria were identified as diagnostic predictors. The conditional probability of each predictor was calculated by summation of the reported frequencies. A model of conditional probabilities and a priori probabilities of cardiac syncope was constructed. The model was tested in four datasets of patients with syncope (the test sample) from Calgary (n=670; 21% had cardiac syncope), Amsterdam (n=503; 9%), Milan (n=689; 5%) and Rochester (3877; 11%). In the derivation sample ten variables were significantly associated with cardiac syncope: age, gender, structural heart disease, low number of spells, brief or absent prodrome, supine syncope, effort syncope, and absence of nausea, diaphoresis and blurred vision. Fitting the test datasets to the full model gave C-statistics of 0.87 (Calgary), 0.84 (Amsterdam), 0.72 (Milan) and 0.71 (Rochester). Model sensitivity and specificity were 92% and 68% for Calgary, 86% and 67% for Amsterdam, 76% and 59% for Milan, and 73% and 52% for Rochester. A model with 5 variables (age, gender, structural heart disease, low number of spells, and lack of prodromal symptoms) was as accurate as the total set., Conclusion: A simple literature-based Bayesian model of historical criteria can distinguish patients with cardiac syncope from other patients with syncope with moderate accuracy.

Clinical decision making can be challenging regarding the emergency department (ED) management of patients with recent syncope. Several models of the syncope management unit are summarized in this article. Assessment of patients with recent syncope in a specialized evaluation unit, such as an emergency department-based syncope management unit, holds great promise in terms of reducing hospital admissions, reducing costs and improving outcomes for patients with syncope., (Copyright © 2013 Elsevier Inc. All rights reserved.)

Introduction: Pacemaker therapy is effective in reducing recurrent syncope in patients with symptomatic carotid sinus hypersensitivity (CSH), yet the optimal pacing modality for this syndrome is not known. The objective of this study is to prospectively investigate the impact of three pacing methods (DDDR vs DDDR with sudden bradycardia response [SBR] vs VVI) on recurrent syncope and quality of life., Methods: Twenty-one patients with symptomatic CSH (syncope or near syncope) were randomized to VVI, DDDR, or DDDR with SBR on a double-blinded basis in a sequential crossover fashion with 6 months in each mode. The primary endpoints were recurrent events and quality of life (assessed by SF-36). The mean number of events and SF-36 scores were compared., Results: At baseline, over the preceding 6 months, there were a total of 29 syncopal events and 258 presyncopal events among 21 patients. Following pacing in any mode, the total number of these syncopal events reduced to two in two patients (P < 0.001) and 17 presyncopal events (P < 0.001) in 12 patients. The mean number of events was not significantly different between the three pacing methods. SF-36 scores revealed some minor benefits of DDDR pacing versus baseline in the categories, but no pacing method was found to be superior., Conclusions: The study was unable to confirm the initial study hypothesis of a superiority of one pacing modality over another. Quality of life measures allude to potential benefit from DDDR pacing alone., (©2012, The Authors. Journal compilation ©2012 Wiley Periodicals, Inc.)

Objective: We assessed the prevalence and distribution of the different causes of transient loss of consciousness (TLOC) in the emergency department (ED) and chest pain unit (CPU) and estimated the proportion of persons with syncope in the general population who seek medical attention from either their general practitioner or the ED/CPU., Methods: A review of the charts of consecutive patients presenting with TLOC at the ED/CPU of our university hospital between 2000 and 2002 was conducted. Patients younger than 12 years or with a known epileptic disorder were excluded. Age and sex of syncopal patients were compared with those in a general practice and general population data sets., Main Findings and Conclusions: During the study period, 0.94% of the patients visiting the ED/CPU presented with TLOC (n = 672), of which half had syncope. Only a small but probably selected group of all people with syncope visit the ED/CPU.

Purpose: Syncope is a common cause of hospitalization in the US. The main objective of this study is to determine the incidence and mortality rates when patients are admitted with a principle diagnosis of syncope., Methods: An observational cross-sectional study included patients with the principle diagnosis of syncope identified from the National Inpatient Sample database for the years 2000-2005. Incidence rate of syncope was adjusted according to the US Census data. In-hospital mortality and its predictors were identified by a logistic regression analysis, and Cochran-Armitage test was used for trend analysis., Results: After data cleansing, 305,932 patients were included in the analysis. Adjusted incidence rate of syncope varied between 0.80 and 0.93 per 1000 person-years and was unchanged over the years included in the analysis. Overall mortality rate is 0.28%, a trend that has not changed over the years (P=0.07). The odds ratio (OR) of death increased with age, becoming more prominent after age 40 years. Hospital mortality is higher in men (OR 1.49; 95% confidence interval [CI], 1.30-1.71) and in patients with higher comorbidity index (OR 1.39; 95% CI, 1.20-1.62) for moderate, and (OR 4.14; 95% CI, 3.05-5.61) for severe comorbidity index. The median cost of hospitalization is $8579, which increased by 3- to 11-fold if patients had a cardiac pacemaker or implantable cardioverter-defibrillator., Conclusions: Syncope remains a common cause of hospital admission. The hospital mortality rate for syncope is low. A better definition and a nationally implemented care path for syncope diagnosis could provide a substantial cost savings.

Syncope is a clinical syndrome characterized by transient loss of consciousness and postural tone that is most often due to temporary and spontaneously self-terminating global cerebral hypoperfusion. A common presenting problem to health care systems, the management of syncope imposes a considerable socioeconomic burden. Clinical guidelines, such as the European Society of Cardiology Guidelines on Management of Syncope, have helped to streamline its management. In recent years, we have witnessed intensive efforts on many fronts to improve the evaluation process and to explore therapeutic options. For this update, we summarized recent active research in the following areas: the role of the syncope management unit and risk prediction rules in providing high-quality and cost-effective evaluation in the emergency department, the implementation of structured history taking and standardized guideline-based evaluation to improve diagnostic yield, the evolving role of the implantable loop recorder as a diagnostic test for unexplained syncope and for guiding management of neurally mediated syncope, and the shift toward nonpharmacological therapies as mainstay treatment for patients with neurally mediated syncope. Syncope is a multidisciplinary problem; future efforts to address critical issues, including the publication of clinical guidelines, should adopt a multidisciplinary approach.

Purpose of Review: In the absence of an established critical pathway to evaluate patients with syncope presenting to the emergency department, this review is timely because of new clinical evidences supporting a specialized syncope management unit in the emergency department, and it is relevant because of the potential impact on a very large and heterogeneous population., Recent Findings: Three observational syncope studies from Italy showed a high degree of variability in practice patterns, diagnostic yields, and lengths of hospital stay. An appropriate and efficacious syncope management pathway in the emergency department remains far from established. In a randomized trial from a tertiary care hospital in the US, the SEEDS study demonstrated that a designated 'syncope unit' in the emergency department, with a multidisciplinary effort and appropriate resources, significantly improved diagnostic yield, reduced hospital admission and total length of hospital stay in intermediate-risk patients. Long-term follow-up showed that reduced hospital stay did not negatively affect survival and recurrent syncope., Summary: Limited randomized trial data suggest a designated syncope unit in the emergency department holds promise to provide specialized and efficient care for patients with syncope. Additional data are needed to assess the general applicability of this critical pathway in community-based hospitals.

Purpose: Our current understanding of the prevalence of syncope is based on a few small studies of highly selected populations. We sought to estimate the prevalence and recurrence rate of syncope in the general population aged more than 45 years and to analyze their associations with age and sex., Methods: We performed a cross-sectional survey of 1925 randomly selected residents of Olmsted County, Minn, 45 years or older, from January 1998 to August 2000., Results: The median age of the 1925 participants was 62 years, and 905 (47.0%) were male. Overall, 364 subjects reported an episode of syncope in their lifetime, giving an estimated prevalence of 19% (95% confidence interval, 17%-21%). The age-specific prevalence rates were 45 to 54 years (20%), 55 to 64 years (20%), 65 to 74 years (15%), and 75 years or more (21%) (P = .86). Females reported a higher prevalence of syncope (22% vs 15%, P < .001)., Conclusions: The prevalence of syncope is estimated at 19% in the general population aged more than 45 years. Females have a higher prevalence, and there is no association of syncope prevalence with age.

Introduction: Our ability to predict a positive electrophysiologic (EP) study in the evaluation of unexplained syncope is suboptimal., Aims: In patients with unexplained syncope, we defined clinical predictors of bradyarrhythmia and ventricular tachycardia (VT) diagnosed during EP study, constructed diagnostic score indices for bradyarrhythmia and VT, and evaluated the predictive power of each score index., Methods: All patients evaluated in the Arrhythmia Clinic for unexplained syncope from January 1, 1996, through December 31, 1998, were identified and enrolled in the study. Five hundred eight patients (325 [64%] men; mean+/-SD age, 64+/-17 years) underwent EP testing. We analyzed elements from historical data and noninvasive laboratory findings as predictors of bradyarrhythmia and VT diagnosed on EP study., Results: Fifty-eight patients (11%) had sinus node dysfunction, 94 (19%) had atrioventricular (AV) node disease, 92 (18%) had His-Purkinje system disease, and 101 (20%) had VT. Models were fit using logistic regression analysis. Predictors were assigned weighted scores, and a score index was formulated. The area under the curve associated with sinus node dysfunction, AV node disease, His-Purkinje system disease, and VT models was 0.64, 0.60, 0.84, and 0.60, respectively., Conclusions: We have constructed diagnostic score indices for EP outcomes of bradyarrhythmia and VT in syncope. Of all the score indices, the model for His-Purkinje system disease has the highest predictive power.

Background: The goal of our study was to determine the accuracy of the American College of Emergency Physicians (ACEP) clinical policy in identifying patients with a cardiac cause for their syncope and its potential effect on syncope management., Methods: Adult patients with syncope presenting to the emergency department (ED) from January 1996 to December 1998 were identified. Diagnosis was established retrospectively by reviewing medical records. The ACEP guidelines were applied to this population., Results: Of the 200 patients identified, 115 (57.5%, 95% CI 60-64) were admitted from the ED and 24 (12%) were found to have cardiogenic syncope. Of the 24 patients with cardiac syncope, 23 were admitted. By applying ACEP level B recommendations to our population, all patients who on further workup were found to have cardiac syncope would have been admitted from the ED (100% sensitivity, 95% CI 86-100) and 81% of patients with no cardiac syncope would have been discharged from the ED (81% specificity, 95% CI 75-87). The admission rate would have been 28.5% (95% CI 22-35). By extending admission to patients satisfying level C in addition to level B recommendations, the sensitivity, specificity, and admission rate would have been 100% (95% CI 86-100), 33% (95% CI 26-40), and 71.0% (95% CI 64-77), respectively., Conclusion: High sensitivity and specificity in identifying patients with cardiogenic syncope and significant reduction in the hospital admission rate were observed by applying ACEP level B recommendations to patients presenting to our ED. Application of level C recommendations did not offer any advantage.

Background: The role of programmed ventricular stimulation (PVS) in patients with idiopathic dilated cardiomyopathy (DCM) and syncope receiving implantable cardioverter-defibrillators (ICD) remains controversial., Methods and Results: Between 1994 and July 2002, 20 patients with DCM and syncope underwent PVS and ICD implantation at the Onassis Cardiac Surgery Center or the Alexandra General Hospital. At PVS 10 patients had inducible sustained monomorphic ventricular tachycardia (SMVT), 3 patients had inducible sustained polymorphic ventricular tachycardia or ventricular fibrillation, and 7 patients had no inducible arrhythmia. The latter 7 patients received an ICD because of clinical occurrence of ventricular tachycardia (n=5) or fibrillation (n=2). Mean age was 55+/-14 years; 80% were men. During a mean follow-up of 2.8+/-2.3 years, 12 of the 20 patients received an appropriate shock. The incidence of appropriate shocks at 1 and 3 years was 69% and 84% in the inducible SMVT group, and 56% and 67% in the group without inducible SMVT (p=0.93, log rank test). Overall survival was similar in both groups (p=0.53). In a systematic review of the published literature 18 of 75 (24%) patients with DCM, syncope and a negative PVS had an appropriate ICD shock after a mean follow-up of 27 months., Conclusion: PVS has a limited role in risk stratification of patients with DCM and syncope.

Objective: To determine the prevalence, predictors, and prognosis of patients with multiple potential causes of syncope., Patients and Methods: This is a retrospective cohort study with prospective follow-up of consecutive patients with syncope of uncertain cause who were referred to the electrophysiology service for syncope evaluation from January 1, 1996, through December 31, 1998. The main outcome measures were prevalence of multiple potential causes of syncope, survival of patients with multiple potential causes of syncope compared with survival of patients with a single cause, and clinical predictors of multiple potential causes of syncope., Results: A total of 987 patients were studied (mean +/- SD age, 58.0 +/- 21.4 years; male, 550 [55.7%]). Multiple potential causes were present in 182 patients (18.4%). Patients with multiple potential causes of syncope had a lower survival rate at 4 years, 73.1% (95% confidence interval, 64.6%-82.8%), vs those with a single cause, 89.3% (95% confidence interval, 86.4%-92.2%) (P < .001). Multivariate predictors of multiple potential causes were older age, atrial fibrillation, use of cardiac medications, and New York Heart Association classification II, III, and IV., Conclusion: Of the patients evaluated for syncope, 18.4% had multiple potential causes. The presence of multiple potential causes was an independent predictor of increased mortality among patients with syncope.

Objective: To determine the effects of phenylephrine and dobutamine on repolarization lability in patients with genotyped long QT syndrome (LQTS)., Patients and Methods: Between December 1998 and August 2000, 23 patients with genotyped LQTS (13 LQT1, 7 LQT2, and 3 LQT3) and 16 controls underwent electrocardiographic stress testing at the Mayo Clinic in Rochester, Minn. Aperiodic repolarization lability was quantified from digitized electrocardiograms recorded during catecholamine stress testing with phenylephrine and dobutamine. T-wave lability was quantified as a root-mean-square of the differences between corresponding signal values of subsequent beats. The magnitude of aperiodic T-wave lability was quantified by using a newly derived T-wave lability index (TWLI)., Results: The TWLI was significantly greater in patients with LQTS than in controls (0.0945 +/- 0.0517 vs 0.0445 +/- 0.0123; P < .003). Marked T-wave lability (TWLI > or = 0.095) was detected in all 3 LQTS genotypes (10/23) but in no controls (P < .003). There was no correlation between the TWLI and the baseline corrected QT interval. All high-risk patients having either a history of out-of-hospital cardiac arrest or syncope had a TWLI of 0.095 or greater., Conclusions: Beat-to-beat nonalternating T-wave lability occurs in LQT1, LQT2, and LQT3 patients during catecholamine provocation and is associated with a history of prior cardiac events. The quantification of this novel phenomenon may assist in identifying LQTS patients with increased risk of sudden cardiac death.

Introduction: Brugada syndrome is an inherited arrhythmic disease associated with major arrhythmic events (MAE). The importance of primary prevention of sudden cardiac death (SCD) in Brugada syndrome is well recognized; however, ventricular arrhythmia risk stratification remains challenging and controversial. We aimed to assess the association of type of syncope with MAE via systematic review and meta‐analysis. Methods: We comprehensively searched the databases of MEDLINE and EMBASE from inception to December 2021. Included studies were cohort (prospective or retrospective) studies that reported the types of syncope (cardiac, unexplained, vasovagal, and undifferentiated) and MAE. Data from each study were combined using the random‐effects, generic inverse variance method of DerSimonian and Laird to calculate the odds ratio (OR) and 95% confidence intervals (CIs). Results: Seventeen studies from 2005 to 2019 were included in this meta‐analysis involving 4355 Brugada syndrome patients. Overall, syncope was significantly associated with an increased risk of MAE in Brugada syndrome (OR = 3.90, 95% CI: 2.22–6.85, p <.001, I2 = 76.0%). By syncope type, cardiac (OR = 4.48, 95% CI: 2.87–7.01, p <.001, I2 = 0.0%) and unexplained (OR = 4.71, 95% CI: 1.34–16.57, p =.016, I2 = 37.3%) syncope was significantly associated with increased risk of MAE in Brugada syndrome. Vasovagal (OR = 2.90, 95% CI: 0.09–98.45, p =.554, I2 = 70.9%) and undifferentiated syncope (OR = 2.01, 95% CI: 1.00–4.03, p =.050, I2 = 64.6%, respectively) were not. Conclusion: Our study demonstrated that cardiac and unexplained syncope was associated with MAE risk in Brugada syndrome populations but not in vasovagal syncope and undifferentiated syncope. Unexplained syncope is associated with a similar increased risk of MAE compared to cardiac syncope. [ABSTRACT FROM AUTHOR]

Presents a hemodynamic analysis of vasovagal syncope induced by isoproterenol intake. Scope of hemodynamic changes after isoproterenol intake; Includes modified cardiac output, heart rate, stroke volume and total peripheral resistance; Sequential changes in hemodynamic variables; Evidence for tilt-induced ventricular filling.