What is the approach to diagnosing and managing syncope (fainting)?

From the Guidelines

The approach to diagnosing and managing syncope involves a systematic evaluation to identify the underlying cause and guide appropriate management, prioritizing the most recent and highest quality evidence from the 2017 ACC/AHA/HRS guideline for the evaluation and management of patients with syncope 1.

Key Components of Evaluation

• Begin with a thorough history, focusing on circumstances surrounding the event, prodromal symptoms, position at onset, duration, and recovery.
• Physical examination should include orthostatic vital signs, cardiac auscultation, and neurological assessment.
• Initial testing includes a 12-lead ECG to identify arrhythmias or structural heart disease.

Management Strategies

• For patients with suspected cardiac syncope, additional tests may include echocardiography, ambulatory cardiac monitoring (24-hour to 30-day depending on frequency of events), and exercise stress testing.
• For vasovagal syncope, which is the most common cause, management includes education about triggers, increased fluid and salt intake, and physical counterpressure maneuvers.
• Medications like midodrine (2.5-10mg three times daily) or fludrocortisone (0.1-0.2mg daily) may be considered for recurrent vasovagal syncope, as supported by earlier guidelines 1.
• Orthostatic hypotension requires addressing underlying causes, medication review, compression stockings, and adequate hydration.
• Cardiac syncope often requires specific interventions such as pacemaker implantation for bradyarrhythmias or ICD for ventricular arrhythmias, as outlined in various guidelines including those from 2009 1 and 2006 1.

Recent Recommendations

• The most recent guideline from 2017 1 emphasizes the importance of identifying the underlying cause of syncope to guide management and improve outcomes.
• The 2021 ACR Appropriateness Criteria for syncope 1 highlight the role of a detailed history and physical examination in evaluating patients with syncope and presyncope, and recommend against routine imaging unless specific indications are present.

Driving Restrictions and Quality of Life

• Driving restrictions should be discussed based on local regulations and syncope etiology.
• The underlying pathophysiology of syncope involves temporary cerebral hypoperfusion, with different mechanisms depending on the cause, including autonomic dysfunction, cardiac output reduction, or vasodilation, as discussed in various studies 1.

From the Research

Approach to Diagnosing Syncope

• The goals of the clinical assessment of a patient with syncope are to identify the precise cause and to quantify the risk to the patient, which depends on the underlying disease rather than the mechanism of the syncope 2.
• A structured approach to the patient with syncope is required, with history-taking being the most important aspect of the clinical assessment 2, 3.
• The classification of syncope is based on the underlying pathophysiological mechanism causing the event, and includes cardiac, orthostatic, and reflex (neurally mediated) mechanisms 2, 4.

Diagnostic Assessment

• The first step of syncope diagnostic assessment is to identify patients with cardiac syncope, and once established, these patients must receive adequate mechanism-specific treatment 4.
• If cardiac syncope is unlikely, reflex (neurally mediated) syncope and orthostatic hypotension are the most frequent causes of transient loss of consciousness 4.
• An initial approach consisting of a careful history, physical examination, and electrocardiograms is essential 3.
• The initial evaluation provides an estimation of risk and directs whether inpatient or outpatient evaluation is appropriate 5.

Management of Syncope

• Patients with life-threatening causes of syncope should be managed urgently and appropriately 2.
• In patients with reflex or orthostatic syncope, it is important to address any exacerbating medication and provide general measures to increase blood pressure, such as physical counter-pressure manoeuvres 2.
• Established mechanism-specific treatment strategies include withdrawal of hypotensive drugs, applying fludrocortisone and midodrine for the hypotensive phenotype, and cardiac pacing in the bradycardic phenotype 4.
• The main objectives of management are to prolong survival, limit physical injuries, and prevent recurrences 2.

Diagnostic Tools and Guidelines

• The investigation of syncope is challenging, and physicians have an ever-increasing array of diagnostic tools at their disposal 5.
• The key to syncope is in the story as told by the patient and a bystander, since this drives both risk assessment and diagnostic testing 5.
• The European Society of Cardiology (ESC) guidelines for the diagnosis and management of syncope provide a structured therapeutic approach for affected patients 6.
• The guidelines emphasize the importance of implantable loop recorders for the evaluation of unexplained syncope and the assessment of potential indications for a definitive treatment with a pacemaker or implantable cardioverter defibrillator (ICD) 6.