Robert S Sheldon

Robert S Sheldon
The University of Calgary | HBI · Department of Cardiac Sciences

MD PhD

About

505
Publications
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17,326
Citations

Publications

Publications (505)
Article
Objectives In this study, the authors tested whether a strategy of empiric permanent pacing reduces major composite events more effectively than acting on the results of an implantable cardiac monitor (ICM). Background Syncope may be caused by intermittent complete heart block in patients with bifascicular heart block, but competing diagnoses coex...
Article
Background: Recurrent vasovagal syncope is common, responds poorly to treatment, and causes physical trauma and poor quality of life. Midodrine prevents hypotension and syncope during tilt tests in patients with vasovagal syncope. Objective: To determine whether midodrine can prevent vasovagal syncope in usual clinical conditions. Design: Rand...
Article
Full-text available
Background The natural history of autonomic alterations following catheter ablation of drug-refractory paroxysmal atrial fibrillation is poorly defined, largely because of the historical reliance on non-invasive intermittent rhythm monitoring for outcome ascertainment. Methods and Results The study included 346 patients with drug-refractory paroxys...
Article
Background: Postural orthostatic tachycardia syndrome (POTS) is a debilitating form of chronic orthostatic intolerance that primarily affects women and causes substantial impairment in quality of life and function. Yet, there is minimal literature describing the employment and economic consequences of POTS. We explored these aspects of the POTS pa...
Article
Purpose: Postural tachycardia syndrome (POTS) and vasovagal syncope (VVS) are two disorders of orthostatic intolerance which are often misdiagnosed as the other. In each case, patients experience a reduced health-related quality of life (HRQoL) compared to healthy populations. This study was conducted to test the hypothesis that HRQoL is worse in...
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Full-text available
Background: We hypothesized that cardiovascular physiology differs in reflex syncope patients compared with the general population, predisposing such individuals to vasovagal reflex. Methods: In this multicohort cross-sectional study, we compared aggregate data of resting SBP, DBP, pulse pressure (PP) and heart rate (HR), collected from six comm...
Article
Background Postural orthostatic tachycardia syndrome (POTS) is a chronic form of orthostatic intolerance associated with a significant symptom burden. Compression garments are a frequently prescribed treatment, but the effectiveness of waist-high compression has not been evaluated in adults with POTS. Objectives This study evaluated compression ga...
Article
Background Protocols that support paramedics to assess, treat and refer low-risk syncope (fainting) may allow for ED transport of only high-risk patients. The development and uptake of such protocols is limited by a dearth of information about factors patients consider when deciding to seek EMS care following syncope.Objective We explored decision-...
Preprint
BACKGROUND We hypothesized that cardiovascular physiology differs in reflex syncope patients compared with general population, predisposing such subjects to vasovagal reflex. METHODS In this multicohort cross-sectional study, we compared resting systolic blood pressure (SBP), diastolic blood pressure (DBP), pulse pressure (PP) and heart rate (HR),...
Article
Aims: Syncope can lead to injuries. We determined the frequency, severity, and predictors of injuries due to syncope in cohorts of syncope patients. Methods and results: Participants were enrolled in the POST2 (fludrocortisone) and POST4 (midodrine) vasovagal syncope (VVS) randomized trials, and POST3 enrolled patients with bifascicular block an...
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Study Objective Patients with syncope are frequently admitted to the hospital, but whether this improves outcome is unknown. We tested whether hospitalization reduced mortality in patients who presented to emergency departments (EDs) with syncope. Methods We conducted a propensity analysis of the outcomes of patients ≥18 years old presenting to ED...
Article
Syncope is a symptom that occurs in multiple settings and has a variety of underlying causes, ranging from benign to life threatening. Determining the underlying diagnosis and prognosis can be challenging and often results in an unstructured approach to evaluation, which is ineffective and costly. In this first ever document, the Canadian Cardiovas...
Chapter
The diagnosis of transient loss of consciousness poses practical challenges. In particular, the distinction between syncope and epileptic seizures is not always made accurately; it can be particularly challenging when the patient might have “convulsive syncope.” Convulsive syncope is observed casually in about 10% of faints but may be much more com...
Article
Vasovagal syncope, postural orthostatic tachycardia syndrome, and inappropriate sinus tachycardia comprise a heterogenous group of common autonomic disorders that are associated with significant symptoms that impair quality of life. Clinical management of these disorders should prioritize conservative non-pharmacological therapies and consider inco...
Chapter
Syncope in the setting of bifascicular block or left bundle branch block raises the etiologic possibility of intermittent complete heart block. However other diagnostic possibilities co-exist, including vasovagal syncope, sick sinus syndrome, and carotid sinus syncope. Either empiric pacing or further diagnostic attempts with tilt tests or implanta...
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Full-text available
Background Implantable cardioverter defibrillator (ICD) acceptance and shock anxiety are measures that clinicians should address to improve quality of life among device recipients. Previous findings have indicated that younger patients experience poorer device adjustment. The purpose of this study was to examine age and ICD-specific quality of life...
Preprint
Full-text available
BACKGROUND Emergency medical services (EMS) assessment and presentation to the emergency department (ED) for syncope (fainting) often results in hospital admission and costly diagnostic testing that rarely benefits patients. Protocols that support paramedics to assess, treat and refer low-risk syncope may allow for ED transport of only high-risk pa...
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Full-text available
Background Syncope is a common presentation to the Emergency Department (ED) yet, little is known regarding patient mode of arrival. Methods We identified patients > 20 years who presented to the ED with a primary diagnosis of syncope in Alberta (AB) and Ontario (ON), Canada between 2010 to 2016. Outcomes included 30-day in-hospital mortality, ED...
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Background Risk stratification is challenging in conditions, such as chest pain, shortness of breath and syncope, which can be the manifestation of many possible underlying diseases. In these cases, decision tools are unlikely to accurately identify all the different adverse events related to the possible etiologies. Attribute matching is a predict...
Article
Objectives This study sought to determine whether sex-specific differences in management and outcomes of syncope patients exist. Background Syncope is a common presentation to the emergency department (ED) and reason for hospital admission. Methods Patients ≥18 years old, presenting to the ED with a primary diagnosis of syncope in Alberta, Canada...
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Background Single-center studies have shown the high costs associated with the hospital evaluation of syncope. National cost estimates for syncope-related hospitalizations are sparse and none exists in Canada. Methods The Canadian Institute for Health Information Discharge Abstract Database was used to identify acute care hospitalizations with a p...
Article
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The current definition of postural orthostatic tachycardia syndrome (POTS) dates back to a small case series of patients with a subacute illness who presented with excessive orthostatic tachycardia and orthostatic intolerance, in the absence of another recognized disease. Conventional POTS criteria require an excessive orthostatic tachycardia in th...
Article
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...
Article
BACKGROUND Drivers at risk of sudden incapacitation from syncope pose a potential threat to themselves and to society. The purpose of this systematic review is to synthesize the risk of motor vehicle collisions (MVC) for patients with a history of syncope. METHODS We systematically searched MEDLINE (1946 – 2019) as well as CINAHL, Embase, Psychinf...
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Syncope is a common presentation to Emergency Departments (EDs). Estimates on the frequency of visits (0.6–1.7%) and subsequent rates of hospitalizations (12–85%) vary according to country. The initial ED evaluation for syncope consists of a detailed history, physical examination and 12-lead electrocardiogram (ECG). The use of additional diagnostic...
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Only humans faint, and not all do so. Syncope tends to recur, and the predisposition to syncope can persist over many decades. Observations such as these have suggested that there may be a genetic predisposition to vasovagal syncope. It seems to have a high prevalence in some families; having a parent who faints increases the likelihood of an offsp...
Article
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 spec...
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Background: Vasovagal syncope (VVS) occurs in > 40% of individuals at least once in their lifetime. Sex-dependent differences in presentation and outcomes are not understood. We sought to determine differences in clinical presentation, treatment modalities, and outcomes of VVS between men and women. Methods: Data were collected as part of the Pr...
Article
Aims: There are few effective therapies for vasovagal syncope (VVS). Pharmacological norepinephrine transporter (NET) inhibition increases sympathetic tone and decreases tilt-induced syncope in healthy subjects. Atomoxetine is a potent and highly selective NET inhibitor. We tested the hypothesis that atomoxetine prevents tilt-induced syncope. Met...
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Background We examined temporal trends, timing, and frequency, as well as adverse neonatal and maternal outcomes occurring in the first year postpartum among women experiencing syncope during pregnancy. Methods and Results This was a retrospective study of pregnancies between January 1, 2005, and December 31, 2014, in the province of Alberta, Cana...
Article
Postural tachycardia syndrome (POTS) is a disorder of the autonomic nervous system with many possible causes, characterized by an unexplained increase in heartbeat without change in blood pressure upon standing. Associated cardiac and noncardiac symptoms can severely affect quality of life. Therapy, using a combined approach of diet and lifestyle c...
Article
Background: Frequent syncope is linked to poorer health-related quality of life (HRQoL). Recurrent syncope has been observed to reduce in all groups after seeing a syncope expert and enrolling in a clinical trial. It is unknown if HRQoL improves with this reduction in syncope recurrence. Objectives: We examined the change in HRQoL over time in v...
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Background: Ambulance use is a costly mode of transportation to the emergency department (ED). Syncope is a frequent presentation to the ED; however, no data exist regarding the proportion of hospitalized patients with syncope arriving by ambulance and their outcomes compared with self-presenters. Methods: The Canadian Institute for Health Infor...
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Background Patients with postural tachycardia syndrome (POTS) experience chronic symptoms of orthostatic intolerance. There is minimal data detailing the demographics, clinical features, and clinical course of this condition. This online, community‐based survey highlights patients’ experience with POTS. It consists of the largest sample of POTS pat...
Article
The aims of this study were (1) to identify research publications studying noninvasive electrocardiogram (ECG) monitoring devices, (2) to define and categorize current technology in noninvasive ECG recording, and (3) to discuss desirable noninvasive recording features for personalized syncope evaluation to guide technological advancement and future...
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Background The purpose of this article is to examine the systemic circulation and left ventricular (LV) performance by alternative, nonconventional approaches: systemic vascular conductance (GSV) and the head-capacity relation (ie, the relation between LV pressure and cardiac output), respectively; in so doing, we aspired to present a novel and imp...
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Syncope in a worker undertaking risky tasks may result in fatalities for the individual or for third parties. We aimed at assessing the rate of syncope recurrence and the risk factors underlying the likelihood of syncope relapse in a working-age population. A prospective cohort of all patients aged 18–65 years consecutively admitted to the Emergenc...
Article
Background: Several studies suggest that vasovagal syncope has a genetic origin, but this is unclear. We assessed whether plausible gene variants associate with vasovagal syncope. Methods: We studied 160 subjects in 9 kindreds comprising 82 fainters and 78 controls. The diagnosis was ascertained with the Calgary Syncope Score. Common genetic var...
Article
Background Vasovagal syncope (VVS) patients have a reduced health‐related quality of life (HRQoL). There are limited data comparing HRQoL and psychological profile in VVS patients and healthy individuals. We tested the hypothesis that VVS patients have greater impairment in both HRQoL and psychological profile compared to healthy non‐fainting indiv...
Article
Background: Atrial fibrillation (AF) and frailty are both associated with advanced age. Oral anticoagulants (OAC) effectively prevent strokes in AF patients but are underutilized in the elderly, possibly due to misperception of frailty. Objective: We performed a systematic review to determine the prevalence of frailty in patients with AF, and wh...
Article
A recent study found syncope hospitalization rates vary across provinces however; it is unknown whether differences in comorbidity burden and outcomes also exist. The Canadian Institute for Health Information Discharge Abstract Database was used to identify primary syncope hospitalizations (ICD-10 code R55) from 2004 to 2013 for all provinces (exce...
Article
Background: Effective communication between the consultants and physicians form an integral foundation of effective and expert patient care. A broad review of the literature has not been undertaken to determine the components of a consultant's letter of most value to the referring physician. We aimed to identify the components of a consultant's le...
Article
Purpose: We hypothesized that heart period (HP) variability in the low frequency (LF) band is due to transient fluctuations of about 10 s in HP sequences, associated with fluctuations in blood pressure. Methods: 10 healthy subjects, mean age 36 y, had HP and blood pressure acquired for 10 min each. Nonrandom HP fluctuations (ripples) lasting 6.7...
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Importance Sparse data and conflicting evidence exist on the prevalence of pulmonary embolism (PE) in patients with syncope. Objective To estimate the prevalence of PE among patients presenting to the emergency department (ED) for evaluation of syncope. Design, Setting, and Participants This retrospective, observational study analyzed longitudina...
Article
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 literatu...
Article
Introduction For patients with bifascicular block and syncope of unknown origin, different American Heart Association guidelines give Class 2A recommendations for two treatments: the implantable loop recorder (ILR) and empiric pacemaker insertion (PM). Equipoise reflected in guidelines may contribute to uncertainty in management and inefficient res...
Article
Background The prevalence, hospitalization patterns, and outcomes of pediatric and adolescent syncope have not been rigorously characterized. Methods Patients <20 years-old presenting to an emergency department (ED) with a primary diagnosis of syncope (ICD-10 code: R55) between fiscal-year (FY) 2006/07 and FY 2013/14 in the province of Alberta, Ca...
Article
Objectives This study sought to examine outcomes and costs of patients with syncope admitted and discharged from the emergency department (ED). Background ED visits for syncope are common, yet the impact on health care utilization is relatively unknown. Methods A total of 51,831 consecutive patients presented to the ED with a primary diagnosis of...
Article
The placebo effect is the clinical benefit caused by interaction with a caregiver and health care system in the absence of a biologically active intervention, and has been used successfully for millennia. The placebo response is due to the interaction of psychosocial mechanisms, human relationships and preconceptions, functioning in specific neuroa...
Article
Background: Syncope is a common clinical presentation and establishing an etiology is often challenging. Pulmonary embolism (PE) has been thought to be an uncommon cause but a recent report suggested otherwise. Objective: To establish the prevalence of PE in patients presenting with syncope to the emergency department (ED) and in hospitalized pa...
Article
Syncope is a common clinical problem that can affect a wide range of patient populations. Like fever, it is a symptom with many causes, and its risk stratification, diagnosis, and treatment are frequently difficult. The purpose of the American College of Cardiology (ACC)/American Heart Association (AHA)/Heart Rhythm Society (HRS) Guideline¹ was to...
Article
Introduction: Syncope is responsible for up to 5% of emergency department visits. Vasovagal syncope (VVS) is the most common subtype and can have significant quality of life implications as it is often recurrent. Clinicians treating VVS have limited treatment options available to them and often struggle with prognostication. The aim of our study wa...
Article
Background: Syncope is common and approaches to establishing etiology remain a matter of clinical and financial importance. Patients often undergo comprehensive neurologic investigations despite a lack of compelling indications. The aim was to determine the prevalence of use and diagnostic yield of electroencephalography (EEG), head computed tomog...
Article
Objectives This study elucidated the temporal recurrence patterns of syncope in patients with frequent vasovagal syncope (VVS). Background Understanding the temporal distribution of fainting spells in syncope patients may illuminate biological processes and inform decision making. Methods Patients from the POST 2 (Prevention of Syncope Trial 2) w...