Research Features Magazine – Understanding syncope – not for the faint hearted
Syncope, commonly known as fainting, occurs when an individual experiences a temporary loss of consciousness caused by a decrease in blood flow to the brain. Professor Robert Sheldon, working at the University of Calgary, has dedicated much of his career to the investigation of syncope and its causes. Over the past three decades, extensive collaborative international research has explored this phenomenon with the aim of providing timely access to high quality care, while giving patients the tools that empower them to manage their condition themselves.
Episodes of ‘syncope’ or sudden fainting followed by a relatively speedy recovery make up approximately 1%–1.5% of all emergency department visits. The tests and diagnoses following these episodes can be extremely varied, making the effective evaluation and treatment of affected individuals difficult. Working closely with international colleagues, Professor Sheldon at the University of Calgary and founder of the Canadian Autonomics and Syncope Alliance, has studied syncope extensively for almost 30 years. This highly collaborative research has forged the way for the development of effective guidelines and improved diagnosis, management and treatment.
Causes of syncope
Syncope episodes can be related to a wide range of biological factors or medical conditions. Vasovagal syncope, mediated by the autonomic nervous system, occurs when an individual’s heart rate and blood pressure react to either physiologic stresses or a particularly disturbing trigger, such as the sight of blood. It is the most common type of syncope, and research shows it has high remission rates. Investigating the frequency patterns of vasovagal syncope episodes in patients who experience recurring episodes (more than four a year), Sheldon and colleagues found these episodes tended to occur at random points in time, with a wide range of frequencies, from less than once a decade to more than monthly. Surprisingly, the tendency to faint stops abruptly in many people.
Syncope can also be part of other underlying medical conditions. These include postural tachycardia syndrome (POTS) characterised by frequent symptoms when standing, including light-headedness, tremor, weakness, exhaustion, and blurred vision, as well as an increased heart rate while shifting from a recumbent to standing position.
A common phenomenon
Syncope episodes are considerably common and a proportion of patients who experience them are admitted to hospital to undergo further assessment to ascertain whether the syncope is related to an underlying medical issue. In order to be exhaustive, tests and assessments need to target several different organ systems, employing different technologies. This process can be time consuming and often requires a substantial amount of resources.
Syncope-related visits to the emergency service that are followed by non-fatal but severe outcomes are a minority and generally only half of these are found to have underlying cardiovascular causes. A recent study by Professor Sheldon and his colleagues analysed syncope hospital admissions over a ten-year period and found that syncope hospitalisation rate was 0.54 per 1,000 population, with 63% of these patients being low-risk, and less than 1% of these patients dying in hospital (Canadian J. of Cardiol, 2017). The varied amount of possible causes for syncope episodes and the fact that following outcomes can range from no consequences to more serious health implications including death, make the assessment of patients approaching emergency services difficult.
Syncope assessment guidelines
Despite syncope patients making up a large proportion of his clinical practice, when Professor Sheldon entered the field almost 30 years ago, very little was known about the condition at that time. To gain a better understanding, Professor Sheldon and his team turned to tilt table tests. This simple research tool ascertained the cause of fainting spells by tilting the patient at different angles (from 60 to 80 degrees), while monitoring heart rate and blood pressure. Although the tilt table became a recognised clinical diagnostic test, Sheldon and his team quickly acknowledged its limitations and embarked on a ten-year programme exploring effective ways to diagnose different syncope types.
Having first highlighted the need to reduce the inaccurate and unnecessary technology to diagnose syncope, by 2006 the collaborators developed a Symptom Score based on historical criteria of patients. This questionnaire detailed symptoms and past medical history, distinguishing vasovagal syncope from syncope of other causes. With its high specificity and sensitivity, it was shown to correctly classify 90% of syncope patients. The Symptom Score is now widely used clinically, resulting in a large reduction of health care utilisation and expenditure. Symptom Scores have also enabled easy patient enrolment into randomised clinical trials and have been used in genetic studies of older patients and other studies with reproducible, objective criteria to guide best practice for diagnostic methods. More recently, the scores have proved invaluable for studies aimed at understanding the roles of placebo and patient–doctor interactions to improve patient outcomes. Professor Sheldon continues to be a strong advocate for the development of new standardised approaches to help doctors quickly and accurately identify the causes of syncope. This is illustrated by his recent participation in the development of an exhaustive guidelines for the evaluation and management of patients with syncope, published by the Heart Rhythm Society in 2016 and the American College of Cardiology /American Heart Association in 2017.
Achieving the gold standard of treatment
There are large disparities between health care systems for the provision of care following syncope. Patients often experience difficulties accessing appropriate care, inappropriate tests are carried out and few people are empowered to manage their own care. Syncope treatments range from pharmacological cycles, to psychiatric or psychological therapy, planned lifestyle changes, invasive interventions and exercise training. The driving force behind a collaborative series of randomised clinical trials, Professor Sheldon investigates effective treatments. Exploring a number of pharmacological treatments for vasovagal syncope, these Prevention of Syncope Trials have demonstrated the probable effectiveness of two common drugs, metoprolol and fludrocortisone. With four additional trials well underway, researchers aim to provide the gold standard in evidence for treating patients with frequent vasovagal syncope.
The patient voice
How best to provide care to people and patients who faint is front and centre for the Canadian Autonomics and Syncope Alliance (CASA). Established in 2013, this national network of syncope patients and investigators fosters synergies and interactions with the aim of delivering better care. Through CASA’s collaboration with the Canadian Arrhythmia Network, syncope has been pushed up the agenda and secured federal support. Their joint goal is to reduce unnecessary emergency department visits and subsequent admissions to hospital. A Patient’s Day hosted by CASA provided a forum to engage patients in planning syncope research strategy. Important priorities for patients included timely access to high quality care and having appropriate tools to help manage syncope independently. Collaborating with the UK organisation STARS UK, Professor Sheldon and colleagues are working to develop and test patient education tools, and through their input into the very international Gargnano Working Group on Syncope Research in the Emergency Department continue to work towards streamlining the emergency care of syncope patients.
Not only has Professor Sheldon advanced the understanding of causes and treatment of different syncope-related conditions, he continues to play a lead role in fostering collaborations highlighting the need for more efficient and standardised care. Advocating the importance of a detailed medical history (rather than investigations) in the assessment of syncope, he is an influential voice promoting a patient-centred approach in a field dominated by technology.
This article originally appeared in Research Features magazine, issue #115. Click here to read more, including a Q & A with Dr. Sheldon.