Are orthostatic vital signs necessary for all patients with syncope?

From the Guidelines

Orthostatic vital signs are not necessary for all patients with syncope, but should be performed selectively in patients with suspected orthostatic hypotension or other conditions that may affect autonomic function, as recommended by the 2017 ACC/AHA/HRS guideline for the evaluation and management of patients with syncope 1. When evaluating patients with syncope, it is essential to consider the potential causes and tailor the diagnostic approach accordingly. Orthostatic vital signs can be useful in identifying orthostatic hypotension, which is defined as a drop in systolic blood pressure of ≥20 mm Hg or diastolic blood pressure of ≥10 mm Hg within 3 minutes of assuming upright posture 1. However, this measurement is not necessary for all patients with syncope, and its utility is limited to specific clinical scenarios.

Some key points to consider when evaluating patients with syncope include:

• The initial evaluation should include a thorough history, physical examination, and electrocardiogram (ECG) to identify potential causes of syncope 1.
• Orthostatic vital signs should be performed in patients with suspected orthostatic hypotension, such as elderly patients, those taking antihypertensive medications, patients with dehydration, or those with conditions affecting autonomic function like Parkinson's disease or diabetes.
• The test involves measuring blood pressure and heart rate while the patient is supine, then after standing for 1-3 minutes, with a positive result typically defined as a drop in systolic blood pressure ≥20 mmHg or diastolic blood pressure ≥10 mmHg, or an increase in heart rate ≥30 beats per minute.
• Other clinical findings, cardiac evaluation, and neurological assessment are often more valuable in determining the etiology of syncope, particularly for cardiac causes which carry higher mortality risk 1.

In summary, while orthostatic vital signs can be a useful diagnostic tool in specific clinical scenarios, they are not necessary for all patients with syncope, and a selective approach based on clinical suspicion and potential causes of syncope is recommended.

From the Research

Orthostatic Vital Signs in Syncope Evaluation

• The utility of orthostatic vital signs (OVS) in evaluating syncope is a topic of discussion among medical professionals 2.
• According to a 2018 study, OVS measurements do not reliably diagnose or exclude orthostatic syncope, nor do they appear to have value in ruling out life-threatening causes of syncope 2.
• However, other studies suggest that orthostatic hypotension can be easily detected by performing an orthostatic challenge with active standing, which is recommended in the presence of any syncope 3.

Diagnostic Approaches

• A 2011 study recommends an algorithmic approach to the evaluation of syncope, starting with history and physical examination, and including electrocardiography, orthostatic vital signs, and QT interval monitoring for all patients presenting with syncope 4.
• The same study suggests that patients with neurally mediated or orthostatic syncope usually require no additional testing, while those with unexplained syncope may require further testing such as echocardiography, grade exercise testing, electrocardiographic monitoring, and electrophysiologic studies 4.
• Another study from 2015 notes that a thorough examination of the patient history is the mainstay of diagnostics for reflex syncope and syncope secondary to orthostatic hypotension, with specific testing only required in uncertain and recurrent cases 5.

Treatment and Management

• Treatment of syncope due to orthostatic hypotension involves correcting reversible causes and discontinuing responsible medications, as well as nonpharmacologic and pharmacologic therapies to improve hypotension and relieve orthostatic symptoms 6.
• A 2015 study suggests that drug treatment, such as alpha-adrenergic agonists and fludrocortisone, is effective only in patients with orthostatic syncope, while pacemaker implantation may be considered in selected patients with reflex syncope of a predominantly cardioinhibitory type 5.