Autonomic nervous system disorders

Update on Diagnostics of Syncope

Faint or Syncope is the sudden loss of consciousness, associated with the inability to maintain postural tone followed by the immediate, spontaneous recovery. It is the cause for 3–5% of all emergency department visits, with a hospitalization rate in about 40% of cases, with an average stay of 5.5 days.

Faint or Syncope is the sudden loss of consciousness, associated with the inability to maintain postural tone followed by the immediate, spontaneous recovery. It is the cause for 3–5% of all emergency department visits, with a hospitalization rate in about 40% of cases, with an average stay of 5.5 days. Beyond this morbidity, there is a recurrence rate of approximately 35% and 29% of physical injury, and major trauma in 4.7% of patients. Besides the social impact with worsening quality of life, there is also the economic impact, with higher costs attributed to hospitalization with an estimated $2.4 billion annual cost (Sun BC. Quality-of-life, health service use, and costs associated with syncope. Prog. Cardiovasc. Dis. 2013; 55: 370–375). Despite this significant socioeconomic impact a minority of patients only obtains guideline oriented syncope-specific diagnostics and therapy. Misdiagnosis may be followed by unsuitable medication and years of uncertainty (http://www.stars.org.uk/patient-stories/misdiagnosis).

In the year 2015, two important consensus articles were published. These have updated recommendations for syncope diagnostics and therapy as well as the management of syncope in the emergency department:
1.    Sheldon RS, Blair BP, Olshansky B et al. 2015. Heart Rhythm Society Expert Consensus Statement on the Diagnosis and Treatment of Postural Tachycardia Syndrome, Inappropriate Sinus Tachycardia, and Vasovagal Syncope . Heart Rhythm; 12:e41-e57
www.ncbi.nlm.nih.gov/pubmed/25980576
The syncope guidelines were agreed between the following societies: The Heart Rhythm Society, American Autonomic Society(AAS), the American College of Cardiology (ACC), the American Heart Association (AHA), the Asia Pacific Heart Rhythm Society(APHRS), the European Heart Rhythm Association (EHRA), the Pediatric and Congenital Electrophysiology Society (PACES), and the Sociedad Latino americana de Estimulacion Cardiaca y Electrofisiologia (SOLAECE)-Latin American Society of Cardiac Pacing and Electrophysiology. The authors tried to include the highest level of evidence for each section and mentioned that a large number of issues are lacking high-level evidence. The paper provided comprehensive overview about the state of current knowledge and evidence of diagnostics and therapy of postural orthostatic tachycardia syndrome (POTS), sinus tachycardia, and vasovagal syncope. Special attention was pathophysiological subtypes of: 1) POTS (hypotensive, hypovolemic, hyperadrenergic) and 2) vasovagal syncope (with either normal or hypotensive blood pressure levels) as well as to the combination of 3) POTS with vasovagal syncope in the young population. At first, a complete history and physical exam with orthostatic vital signs should be taken. A 12-lead ECG at rest and exercise should be performed on patients being assessed for POTS. The authors pointed out that tilt-table testing is useful especially, for assessing patients with suspected vasovagal syncope. Recurrent unexplained syncope should additionally be assessed via prolonged electrocardiography. With POTS and vasovagal syncope, non-pharmacological treatments should be attempted first. Medication which could increase the risk of further events should be withdrawn. In most patients further syncope can be prevented by increasing blood volume with enhanced salt and fluid intake, reducing venous pooling with compression garments as well as specific exercise programs for POTS or counterpressure maneuvers and tilt training for vasovagal syncope. If though necessary, medications as for instance fludrocortisone, midodrine, mestinone, or even betablocker can be applied according to the pathophysiological subtype of POTS or vasovagal syncope. In patients with vasovagal asystole, pacing should be considered only in highly selected patients, such as those significantly older than 40 years or patients who experience frequent asystole events associated with repeated injury, limited prodromes, and documented asystole.

2.    Costantino G, Sun BC, Barbic F, Bossi I, Casazza G, Dipaola F et al. Syncope clinical management in the emergency department: a consensus from the first international workshop on syncope risk stratification in the emergency department. European Heart Journal, doi:10.1093/eurheartj/ehv378

www.ncbi.nlm.nih.gov/pubmed/26242712


The second consensus paper was published in the aftermath of the first international workshop on syncope risk stratification in the emergency department. The authors developed a conceptual model for the syncope management in the emergency department which included the stratification of risk factors of serious or unfavorable outcome. Syncope patients in the emergency department should be stratified into three different risk categories according to the characteristics. Low-risk patients could be safely discharged and further diagnosed in outpatient clinics. High-risk patients with concomitant cardiac complaints, syncope in supine, sitting position, during exercise as well as cardiovascular or ECG abnormalities should be assessed and treated more urgently. Both, 12 lead ECG and ECG monitoring should be performed to exclude causative abnormalities (as for instance, AV block >I, ischemia, Brugada pattern, QTc > 450ms), arrhythmia, or pause. Patients should be managed in the emergency department with ECG monitoring and other diagnostic tools, as appropriate. There is no consensus about the duration of monitoring. Emergency department observation protocols and referral to an outpatient syncope clinic or syncope unit is recommended.