Task force on syncope, European Society of Cardiology. Part 2. Diagnostic tests and treatment: summary of recommendations

Twenty-five years of research on syncope

Over the last 25 years, the Europace journal has greatly contributed to dissemination of research and knowledge in the field of syncope. More than 400 manuscripts have been published in the journal. They undoubtedly improved our understanding of syncope. This symptom is now clearly differentiated from other forms of transient loss of consciousness. The critical role of vasodepression and/or cardioinhibition as final mechanisms of reflex syncope is emphasized. Current diagnostic approach sharply separates between cardiac and autonomic pathways. Physiologic insights have been translated, through rigorously designed clinical trials, into non-pharmacological or pharmacological interventions and interventional therapies. The following manuscript is intended to give the reader the current state of the art of knowledge of syncope by highlighting landmark contributions of the Europace journal.

Modified criteria for carotid sinus hypersensitivity are associated with increased mortality in a population-based study

AIMS

Carotid sinus hypersensitivity (CSH) is arbitrarily defined as ≥3 s asystole or vasodepression of ≥50 mmHg in response to carotid sinus massage (CSM). Using this definition, 39% of older people meet the criteria for CSH. It has been suggested that current criteria are too sensitive. Krediet et al. [The history of diagnosing carotid sinus hypersensitivity: why are the current criteria too sensitive? Europace 2011;13:14-22] and Kerr et al. [Carotid sinus hypersensitivity in asymptomatic older persons: implications for diagnosis of syncope and falls. Arch Intern Med 2006;166:515-20] have proposed modified criteria. This population-based study aimed to compare the prevalence of CSH defined according to standard, Krediet and Kerr criteria, and to establish if CSH defined according these criteria is associated with all-cause mortality.

METHODS AND RESULTS

A total of 272 community-dwelling people aged ≥65 were recruited at random. Carotid sinus massage was performed for 5 s in supine and head-up positions. Heart rate and blood pressure response were recorded using an electrocardiogram and photoplethysmography. Cox regression analysis was used to examine the association between each definition of CSH and all-cause mortality. The prevalence of CSH defined according to standard, Krediet, and Kerr criteria was 39, 52, and 10%, respectively. Seventy-one participants died over a mean follow-up of 8.6 years (SD 2.1). Carotid sinus hypersensitivity defined according to standard and Krediet criteria was not associated with survival. Carotid sinus hypersensitivity defined according to Kerr criteria was associated with all-cause mortality independent of age and sex [hazard ratio (HR) 2.023 (95% confidence interval (95% CI) 1.131-3.618) P = 0.018)]. This remained significant after adjusting for cardiovascular risk factors [HR 2.174 (1.075-3.900) P = 0.009].

CONCLUSION

Carotid sinus hypersensitivity defined according to Kerr criteria is associated with increased mortality. This raises an interesting question as to the suitability of the current criteria used to define CSH.

Diagnosing orthostatic hypotension: a narrative review of the evidence

BACKGROUND

Orthostatic hypotension (OH) is very common, particularly in older populations. Diagnostic criteria exist but appear to be arbitrary rather than evidence based. This review will visit the evidence for diagnostic strategies for OH.

DATA SOURCES

Medline (OvidSP), EMBASE (OvidSP), ISI Web of Science, the Health Technology Assessments Database and the Cochrane Library.

AREAS OF AGREEMENT

A 5-min rest is required before measuring baseline. An active stand with continuous blood pressure (BP) monitoring is preferable to a tilt test to identify initial OH in particular. At least 2 min in the upright position is required. A systolic drop of 20 or a diastolic drop of 10 is supported by the evidence. Reproducibility when testing for OH is poor.

AREAS OF CONTROVERSY

Is the active stand preferable to the tilt test to diagnose classical OH? Although continuous BP monitoring increases diagnostic rates, does it improve clinical outcomes? Should symptoms be used to inform diagnosis?

AREAS TIMELY FOR RESEARCH

Establishing the long-term clinical outcomes for transient drops in BP detected on continuous, non-invasive monitoring. Evaluating the different patterns of BP drop to aid diagnosis and direct treatment.

The Role of the Syncope Management Unit

Syncope is a common symptom, experienced by 15% of persons less than 18 years old and up to 23% of elderly nursing home residents, so it is important to consider optimizing strategies for the management of these patients. The strategy selected will inevitably differ from place to place. However, an organized structure offers more cost-effective care. This article discusses possible health care delivery models for syncope management and reviews the current status of the organization of syncope care, to show the value of a multidisciplinary approach to the organized management of patients with syncope.

Tilt testing with combined lower body negative pressure: a "gold standard" for measuring orthostatic tolerance

Orthostatic tolerance (OT) refers to the ability to maintain cardiovascular stability when upright, against the hydrostatic effects of gravity, and hence to maintain cerebral perfusion and prevent syncope (fainting). Various techniques are available to assess OT and the effects of gravitational stress upon the circulation, typically by reproducing a presyncopal event (near-fainting episode) in a controlled laboratory environment. The time and/or degree of stress required to provoke this response provides the measure of OT. Any technique used to determine OT should: enable distinction between patients with orthostatic intolerance (of various causes) and asymptomatic control subjects; be highly reproducible, enabling evaluation of therapeutic interventions; avoid invasive procedures, which are known to impair OT(1). In the late 1980s head-upright tilt testing was first utilized for diagnosing syncope(2). Since then it has been used to assess OT in patients with syncope of unknown cause, as well as in healthy subjects to study postural cardiovascular reflexes(2-6). Tilting protocols comprise three categories: passive tilt; passive tilt accompanied by pharmacological provocation; and passive tilt with combined lower body negative pressure (LBNP). However, the effects of tilt testing (and other orthostatic stress testing modalities) are often poorly reproducible, with low sensitivity and specificity to diagnose orthostatic intolerance(7). Typically, a passive tilt includes 20-60 min of orthostatic stress continued until the onset of presyncope in patients(2-6). However, the main drawback of this procedure is its inability to invoke presyncope in all individuals undergoing the test, and corresponding low sensitivity(8,9). Thus, different methods were explored to increase the orthostatic stress and improve sensitivity. Pharmacological provocation has been used to increase the orthostatic challenge, for example using isoprenaline(4,7,10,11) or sublingual nitrate(12,13). However, the main drawback of these approaches are increases in sensitivity at the cost of unacceptable decreases in specificity(10,14), with a high positive response rate immediately after administration(15). Furthermore, invasive procedures associated with some pharmacological provocations greatly increase the false positive rate(1). Another approach is to combine passive tilt testing with LBNP, providing a stronger orthostatic stress without invasive procedures or drug side-effects, using the technique pioneered by Professor Roger Hainsworth in the 1990s(16-18). This approach provokes presyncope in almost all subjects (allowing for symptom recognition in patients with syncope), while discriminating between patients with syncope and healthy controls, with a specificity of 92%, sensitivity of 85%, and repeatability of 1.1±0.6 min(16,17). This allows not only diagnosis and pathophysiological assessment(19-22), but also the evaluation of treatments for orthostatic intolerance due to its high repeatability(23-30). For these reasons, we argue this should be the "gold standard" for orthostatic stress testing, and accordingly this will be the method described in this paper.

Evaluation of risk of falls and orthostatic hypotension in older, long-term topical beta-blocker users

BACKGROUND

Falls are a serious problem in the elderly, and have recently been described as cardiovascular-mediated side effects of beta-blocker eye drops. Therefore, we investigated the possible association between the long-term use of beta-blockers, prostaglandins and their combinations in eye drops, and falls, dizziness and orthostatic hypotension in older patients.

METHODS

All participants were long-term users of eye drops containing beta-blockers, prostaglandins or their combinations. They underwent a structured falls interview and blood pressure measurement for testing of orthostatic hypotension. The odds ratio for presence of orthostatic hypotension or a positive falls history according to use of beta-blocker eye drops was calculated with a binary logistic regression analysis. The main outcome measures were a positive falls history and the presence of orthostatic hypotension.

RESULTS

In total, 148 of 286 subjects participated. After adjustment for age, gender, and use of fall-risk-increasing drugs other than beta-blocker eye drops, we found no significant difference in fall risk [odds ratio (OR): 0.60; 95% confidence interval (CI): 0.268-1.327] between patients using ophthalmic beta-blockers or a combination of ophthalmic beta-blockers and prostaglandins, and patients using ophthalmic prostaglandins only. Although prevalence of orthostatic hypotension was higher in the beta-blocker group (OR: 1.67; 95% CI: 0.731-3.793) compared to the prostaglandin group, this was a non-significant difference.

CONCLUSIONS

In our study, we did not find a significant association between long-term use of beta-blockers eye drops and falls, dizziness or orthostatic hypotension in older ophthalmic outpatients, compared to long-term use of prostaglandin eye drops.

Neurological aspects of syncope and orthostatic intolerance

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

Postural syncope: mechanisms and management

Postural syncope is a transient loss of consciousness secondary to a reduction in cerebral blood flow and is typically precipitated by standing. It is the commonest cause of recurrent transient loss of consciousness. Recurrent unexplained postural syncope is most often due to one of the five disorders of circulatory control: vasovagal syncope, postural tachycardia syndrome, chronic autonomic failure, initial orthostatic hypotension, or persistently low supine systolic blood pressure. Failure to identify the underlying cause of postural syncope can result in ongoing morbidity, impaired quality of life and high health care costs. With a detailed history, examination, blood pressure assessment and electrocardiography, most disorders of circulatory control can be diagnosed. In difficult cases, analysis of sympathetic nervous system and circulatory responses during head-up tilting can aid diagnosis. Treatment is challenging and compounded by a lack of evidence. Most patients can be managed in an outpatient setting, and hospital admission or emergency department assessment is rarely warranted.

Assessment of cardiovascular autonomic function

Autonomic assessment has played an important role in elucidating the role of the autonomic nervous system in diverse clinical and research settings. The techniques most widely used in the clinical setting entail the measurement of an end-organ response to a physiological provocation. The non-invasive measures of cardiovascular parasympathetic function involve the analysis of heart rate variability while the measures of cardiovascular sympathetic function assess the blood pressure response to physiological stimuli. Prolonged tilt-table testing, with or without pharmacological provocation, has become an important tool in the investigation of a predisposition to neurally mediated (vasovagal) syncope. Frequency domain analyses of heart rate and blood pressure variability, microneurography, occlusion plethysmography, laser Doppler imaging and flowmetry, and cardiac sympathetic imaging are currently research tools but may find a place in the clinical assessment of autonomic function in the future.

The clinical impact of implantable loop recorders in patients with syncope

AIMS

Implantable loop recorders (ILR) provide an opportunity to record ECG data from a spontaneous syncopal event. We conducted a randomized study to investigate the impact of the Reveal Plus ILR on an unselected population of patients with recurrent syncope. Initial follow-up (at least 6 months) did not demonstrate a reduction in syncopal events or an improvement in quality of life. We report the planned extension of follow-up to 18 months.

METHODS AND RESULTS

All patients presenting acutely with recurrent unexplained syncope over a 16-month period, following a basic clinical work-up, were randomized to receive the ILR or conventional investigation and management. A total of 421 patients presented, 201 were eligible, median age 74, (IQ range 61-81) 54% female, with median syncopes 3 (IQ range 2-6). Median follow-up 17 months (IQ range 9-23). 42 (43%) of ILR patients and 8 (6%) of conventional patients received an ECG diagnosis (hazard ratio 6.53, 95% CI 3.73-11.4, P<0.001). Time to second syncope was significantly longer for ILR patients, although of borderline significance (P=0.04). A greater variety of diagnoses and treatments were seen in ILR patients. ILR patients had fewer post-randomization investigations and fewer days in hospital; however, cost savings were not statistically significant. There was improved quality of life in the ILR group (visual analogue scales, P=0.03) for general wellbeing. Overall mortality was 12% with no difference between the two groups.

CONCLUSION

Investigation by the ILR significantly increases the diagnostic rate and ECG directed treatments in a typical unselected syncopal population. Long-term follow-up has demonstrated a significant subsequent reduction in syncopal events with improved quality of life.

Leg crossing, muscle tensing, squatting, and the crash position are effective against vasovagal reactions solely through increases in cardiac output

Tensing of lower body muscles without or with leg crossing (LBMT, LCMT), whole body tensing (WBT), squatting, and sitting with the head bent between the knees (“crash position,” HBK) are believed to abort vasovagal reactions. The underlying mechanisms are unknown. To study these interventions in patients with a clinical history of vasovagal syncope and a vasovagal reaction during routine tilt table testing, we measured blood pressure (BP) continuously with Finapres and derived heart rate, stroke volume, cardiac output (CO), and total peripheral resistance using Modelflow. In series A ( n = 12) we compared LBMT to LCMT. In series B ( n = 9), WBT was compared with LCMT. In series C ( n = 14) and D ( n = 9), we tested squatting and HBK. All maneuvers caused an increase in BP, varying from a systolic rise from 77 ± 8 to 104 ± 18 mmHg ( P < 0.05) in series A during LBMT to a rise from 70 ± 10 to 123 ± 9 mmHg ( P < 0.05) in series B during LCMT. In each maneuver, the BP increase started within 3–5 s from start of the maneuver. In all maneuvers, there was an increase in CO varying from 54 ± 12% of baseline to 94 ± 21% in WBT to a rise from 65 ± 17% to 110 ± 22% in LCMT in series A. No maneuver caused significant change in total peripheral resistance. We conclude that the mechanism underlying the effects of these maneuvers is exclusively an increase in CO.

Approach to the patient with epilepsy in the outpatient department

Epilepsy is common and serious (prevalence 750 per 100 000) and has an impact upon employment, education, and driving. The diagnosis requires a detailed history including witness account. Clinicians must distinguish seizures particularly from syncope and psychogenic attacks. Electroencephalography and magnetic resonance brain scanning help to identify causes and classification of epilepsy, but alone rarely provide the diagnosis. Antiepileptic drug treatment is required long term and is potentially hazardous; patients should start treatment only after informed discussion with an epilepsy specialist. Patients require reliable written information, particularly the driving regulations, and the impact of seizures on employment, education, and leisure. Women must understand the potential drug teratogenic effects. Certain patient groups benefit from targeted epilepsy services, for example, learning disabled, children, teenagers, and elderly. People with epilepsy require long term specialist follow up. Although this is currently provided in mainly in secondary care (including nurse led clinics), improved liaison with primary care should enable improved access to epilepsy services. Epilepsy care should be multidisciplinary and long term, linking primary and secondary care, and empowering patients towards improved management of their condition.

New approaches to the treatment and prevention of neurally mediated reflex (neurocardiogenic) syncope

Neurally mediated reflex syncope (sometimes referred to as neurocardiogenic syncope), encompasses a group of disorders of which the best known and most frequently occurring forms are the vasovagal (or common) faint, and carotid sinus syndrome. Postmicturition syncope, defecation syncope, cough syncope, and other situational reflex faints are also included among these conditions. With the exception of carotid sinus syndrome in which cardiac pacing is effective, treatment of most neurally mediated reflex faints is shifting from reliance on various drugs to greater emphasis on education and nonpharmacologic therapy. Initial management should include counseling of patients regarding recognition of early warning symptoms, and avoidance of precipitating factors. Volume expansion with salt tablets or electrolyte-containing beverages and patient education on how to perform isometric arm contractions and/or leg crossing in order to abort impending syncope are also important. Thereafter, tilt-training has demonstrated benefit in several clinical studies. When symptoms remain despite the above-noted interventions, pharmacologic therapy with midodrine or a nonselective b-blocker can be considered. In the case of most neurally mediated reflex faints, permanent cardiac pacing should be reserved only for those older patients with significant bradycardia or asystole at time of syncope when all other interventions have failed.

Syncope in children and adolescents and the congenital long QT syndrome

From a population-based epidemiologic cohort of children and adolescents who sought medical attention for syncope (n = 151), screening 12-lead electrocardiograms were obtained from 118 patients (79 female) to determine the frequency of significant QT prolongation. The distribution of heart rate corrected QT intervals (QTc) was compared with age- and sex-matched controls. Only one patient had QTc >470 ms.

Syncope and orthostatic intolerance

Syncope and orthostatic intolerance remain common and significant clinical problems with many undocumented, misdiagnosed, or cryptogenic cases. Careful clinical assessment and application of advancing laboratory support can further improve diagnosis and treatment. Despite the depth of existing research into these common problems, many underlying mechanisms remain unproven.