Emphasis is placed on a detailed clinical history obtained from patients or eyewitnesses. The history taking has multiple aims: to establish whether loss of consciousness occurred, to determine whether the loss of consciousness was of syncopal origin, to identify its etiology, and to stratify the risk. A novel inclusion is the additional material in the “Practical Instructions”. The recommended diagnostic criteria of reflex syncope, orthostatic hypotension, and cardiac syncope have not undergone substantial changes from the previous guidelines. Helpfully, the guidelines offer practical solutions based on the extensive experience of the members of the ESC working group.

Management of syncope in the emergency department according to risk stratification. One of the most novel aspects of the guidelines is the recommendations for the management of syncope in the emergency department. The main objective of this approach is to reduce the hospital admission rate without compromising patient safety. The guidelines clearly detail the low- and high-risk factors that can be obtained from the clinical history, physical examination, and electrocardiogram. The indications for other complementary examinations are established (hospital monitoring for suspected arrhythmic syncope, echocardiography if there is evidence of structural heart disease, carotid sinus massage in patients older than 40 years of age, tilt-table (TT) testing when there is a suspicion of reflex or orthostatic syncope, and laboratory analyses to rule out secondary causes when required). The authors note that high-risk patients are more likely to have cardiac syncope and, therefore, have a higher risk of sudden death than low-risk patients who, in contrast, are more likely to have reflex syncope and good prognosis.

Not all high-risk patients require hospitalization. The document stresses that SUs are a safe and effective alternative. The guidelines recommend (class I B) that low-risk patients without recurrence be discharged from emergency departments, that high-risk patients be admitted or exhaustively evaluated in emergency departments or SUs, and that patients without high- or low-risk criteria be studied in emergency department observation units or referred to SUs instead of being admitted. Low-risk patients requiring specific treatment (eg, due to multiple recurrences) can be referred to SUs. Risk stratification algorithms are noted to not be superior to clinical judgment in predicting severe short-term events: their use is a class IIb recommendation. A novelty is the equal consideration of presyncope and syncope, introduced because evidence indicates that they have the same prognosis.

The published experience on the implementation of SUs in Spain is scarce,3 although the SEC-EXCELENTE project provides a unique opportunity for the creation of units with specific and homogeneous quality standards.

There are no changes to diagnostic tests, but a change in “philosophy” is seen with the promotion of the study of dysautonomia as a possible cause of neuromediated syncope. A reasoned step is the incorporation of the neurologist's viewpoint and of neurological tests into the diagnosis and, although to a lesser extent, into the treatment.

Carotid sinus massage. Because it is one of the most cost-effective tests, the guidelines insist that carotid sinus massage be performed in the initial evaluation of patients older than 40 years. There are no changes in the level of indication or in the positive diagnostic criteria (presence of syncope together with ventricular pause> 3seconds or a systolic blood pressure fall> 50mmHg). There is another major consideration: the guidelines no longer deem the test contraindicated in patients with stroke in the previous 3 months or with carotid murmurs. Other considerations deserving comment are as follows:

• •

  Carotid sinus massage must be performed first in decubitus and then in orthostatism (usually in the TT, unless the test was already positive).

• •

  A somewhat confusing comment is added: carotid sinus massage is indicated for syncope of unknown origin “compatible with a reflex mechanism”. It appears that this statement has been added so that a more serious form of syncope is not diagnosed in a patient with a positive test result.

• •

  Greater emphasis could have been placed on the diagnosis of carotid hypersensitivity because its value is supported in the literature.4 The guidelines do mention that asymptomatic pauses exceeding 3seconds (carotid sinus hypersensitivity) have little value in the diagnosis of syncope etiology.

• •

  With a positive test result, both components (vasodepressor and cardioinhibitor) must be identified. This requires 2 actions: repeating the test with noninvasive “beat-to-beat” blood pressure measurement after atropine and a TT test. Detection of a dominant vasodepressor component would contraindicate pacemaker (PM) implantation.

Orthostatic challenge. This initial test is basic but cost-effective and has high diagnostic value. Its level of indication has fallen from I B to I C but the classic diagnostic criteria are maintained (I C if syncope occurs during the test and IIa C if there is a significant fall in blood pressure but no syncope). The initial orthostatic intolerance (that occurring <30seconds after the orthostatism) cannot be diagnosed with a sphygmomanometer and a “beat-to-beat” measurement is necessary (IIb C indication). Postural orthostatic tachycardia syndrome (POTS) is precisely defined as an increase in heart rate of more than 30 beats or a rate exceeding 120 bpm with associated symptoms and without hypotension. The definition does not note that the increase should exceed 40 bpm in adolescents, as recommended by the consensus statement on orthostatic hypotension and POTS.5

Tilt-table. The subtlest change in the document is related to this test. Initially, it seems downgraded–as a diagnostic test, its recommendation drops from I B to IIa B–and the diagnostic criteria indication falls from I to IIa. In addition, its lack of ability to direct management is maintained. However, its applications are numerous: vasodepressor component assessment, differential diagnosis (epilepsy, psychiatric syncope), ventricular pause evaluation, prodrome recognition training, research, or videoelectroencephalography. The TT is now considered useful for assessing “hypotensive tendency”. Its usefulness is clear in the context of orthostatic intolerance (either POTS or neurogenic hypotension).

The guidelines maintain the treatment framework based on risk stratification and identification of the specific mechanism when possible. Greater emphasis is placed on the importance of the syncope mechanism to ensure effective prevention of recurrences with treatment.

Clear differentiation of the treatment objectives is missing: to prolong life, to eliminate or diminish the physical (or mental) consequences, and to avoid recurrences. Based on the text, the only evident treatment objective is to avoid recurrence.

The favorable prognosis of this entity and the probability of recurrence are reiterated. The guidelines stress lifestyle recommendations and the identification and prevention of triggering factors as a critical element of treatment. Education is associated with reduced mortality and fewer complications in other cardiovascular diseases.8,9 The novelty here is the introduction of a patient instruction sheet, written for patients and family members, which is highly useful for strengthening health education. The main limitation is the lack of scientific evidence in the area of syncope.

A novel inclusion is a practical and clear schematic on the treatment of reflex syncope. The aforementioned educational measures stand out as the first therapeutic step to be performed in all cases.

The recommendation level of the indication for isometric physical counterpressure maneuvers is reduced (from I B to IIa B). This reduction is due to its low usefulness in the ISSUE-3 trial in elderly patients without prolonged and recognizable prodromes. Because the maneuvers can be useful in young patients with a prolonged prodromal period, they are detailed in the “Practical Instructions”.

The recommendation for tilt training remains class IIb B. It is a potentially useful but impractical approach, and difficult to maintain for a prolonged period, and there is no new relevant evidence.

A new indication is to eliminate or reduce the hypotensive treatment of patients with vasodepressor syncope. This recommendation has clear clinical usefulness because it is highly feasible and there is no deleterious effect on blood pressure control in the studies cited.

The use of the alpha-adrenergic agonist midodrine in patients with vasovagal syncope resistant to educational measures is maintained as a IIb B recommendation, and the class III A recommendation is maintained for the contraindication to beta-blockers.

A new feature is the introduction of fludrocortisone, although it is only useful at high doses and is contraindicated for elderly and hypertensive patients, which is why its usefulness in real-world clinical practice is limited.

Cardiac pacing. Since the last guidelines, substantial evidence has been generated on the efficacy of PMs for the treatment of reflex syncope. In patients older than 40 years, when the mechanism is predominantly cardioinhibitory, dual-chamber PMs (in DDD pacing mode) significantly reduce recurrences. Hence, bradyarrhythmia documentation is fundamental.

Four possible indications are defined, the first 3 for patients older than 40 years: a) documentation of spontaneous bradyarrhythmia (IIa B); b) carotid sinus syndrome with cardioinhibitory mechanism (IIa B); c) asystole induced in the TT test (IIb B); and d) adenosine-sensitive syncope (IIb B).

One controversial aspect, as acknowledged by the authors themselves, is that, for asystole induced in the TT test, the indication for PM implantation is reduced to class IIb and documentation of spontaneous bradyarrhythmia is prioritized. This is despite 2 studies showing that PM implantation significantly reduces recurrences in these patients.10,11

Years have passed but the treatment remains the same and as weakly effective as ever. Only water and salt intake has a class I C indication. There is little evidence of its effectiveness: in the American guidelines, the recommendation is IIb.12 The other usual physical measures have IIa recommendations. Of the drugs, only midodrine and fludrocortisone have a IIa indication. Droxidopa, the only drug besides midodrine to be approved by the FDA, is not recommended, and neither are beta-blockers, in contrast to the American guidelines, which assigns them class IIa and IIb indications, respectively. Appropriately, the guidelines stress that hypertensive elderly people with syncope can be more tolerant of hypotensive treatment.

Syncope due to intrinsic sinoatrial or atrioventricular conduction system disease. The indications for PM implantation have not been substantially modified. Two aspects are detailed: a) in patients with sinus node disease without documentation of symptomatic pauses, the recommendation is to rule out other diagnostic alternatives (particularly reflex syncope) before PM implantation in order to reduce the high rate of syncopal recurrences, which is as high as 28% in some series; and b) in patients with syncopes and bifascicular block on ECG, in order to establish the PM indication, the recommendation is to document the pathological findings in an electrophysiological study or via a significant pause on an implantable loop recorder.

Syncope due to tachyarrhythmias. Catheter ablation is the treatment of choice to prevent syncope in patients with supraventricular and ventricular arrhythmias (specifically in susceptible substrates, fundamentally monomorphic ventricular tachycardia).

Two notes are made: a) to individualize the therapeutic option (ablation or drugs) for atrial fibrillation and left atrial flutter (medical therapy was prioritized in previous guidelines); b) to consider implantable cardioverter-defibrillator (ICD) placement after documentation of ventricular arrhythmias in order to reduce mortality in individuals with a left ventricular ejection fraction (LVEF) ≤ 35% (I A) or with previous infarction and induction of tachycardia ventricular (I C). A cutoff point for LVEF is a more specific criterion than the previous, looser, concept of “structural heart disease”.

Syncope due to intrinsic sinoatrial or atrioventricular conduction system disease. To prevent recurrences, the guidelines stress that the focus for these patients should be on treatment of the underlying disease (to improve the prognosis) and not only on the etiological study of the syncope (not always arrhythmic).

Treatment of unexplained syncope in patients at high risk of sudden cardiac death. This section deals with patients with syncope presumably due to ventricular arrhythmias that have not been documented. Therefore, they are “syncopes of unknown origin” that, when occurring in individuals at high risk of ventricular arrhythmias, suggest an arrhythmic origin (“suspected arrhythmic syncope”).

There are 2 options: a) ICD therapy, given that, in this environment, syncope significantly increases the risk of sudden cardiac death; and b) completion of the etiological study (with the intention of documenting the clinical arrhythmia) via placement of an implantable loop recorder in low-risk individuals without an indication for ICD.

The final decision should integrate all of the available information, even though, except for hypertrophic cardiomyopathy, there are no validated risk scales. Thus, the level of evidence for most of the indications is C.

Regarding left ventricular dysfunction, the ICD indications are respected to prevent the occurrence of sudden cardiac death in patients with depressed function, according to the recognized indications. The indication is introduced for patients without an indication in the previous section–which may include individuals with reduced LVEF that exceeds 35%–with a IIa C level. For these patients, an implantable loop recorder can be considered, with a IIB C level.

Surprisingly, the electrophysiological study is not mentioned as a diagnostic tool, despite its proven usefulness in patients with syncope and myocardial infarction. Paradoxically, this recommendation is included in the section dedicated to the electrophysiological study as a I B indication.

Neurological evaluation has a class I C indication if there is autonomic failure or suspected epilepsy. Epilepsy is probably the most difficult differential diagnosis of syncope and is thus widely discussed in the guidelines. Of particular importance for cardiologists is “ictal asystole” in the context of partial seizures because their final treatment, in addition to antiepileptic drugs, may include PM implantation. Fortunately, it is a very rare condition and should not be confused with sudden death in epileptic patients (typically occurring in patients after nocturnal generalized tonic-clonic seizures). There is a brief mention of other diseases such as stroke, migraine, cataplexy, and drop attacks.

The authors stress that electroencephalography, Doppler imaging of the supraaortic trunks, and brain computed tomography or magnetic resonance imaging (MRI) are not indicated for syncope (class III B recommendation). However, importantly, in contrast to the previous guidelines, brain MRI (I C) is recommended in patients with signs of parkinsonism, ataxia, or cognitive impairment. Electroencephalography is only useful in doubtful cases or to establish the diagnosis of psychogenic syncope if an induced episode is recorded. A novelty is the recommendation (I B) for paraneoplastic antibody screening (and active searching for occult neoplasia if positive) and antiganglionic acetylcholine receptor antibodies in patients with acute or subacute onset of autonomic dysfunction. A diagram is proposed for the explorations to be performed on patients with autonomic dysfunction that indicates imaging tests, skin biopsy, and even genetic tests depending on the clinical presentation. Additional information on the interpretation of these examinations is provided on the web.