What does a positive tilt table test indicate?

From the Guidelines

A positive tilt table test indicates that a person has orthostatic intolerance, most commonly neurally mediated syncope (vasovagal syncope) or postural orthostatic tachycardia syndrome (POTS). During the test, when the patient is tilted upright, they experience symptoms such as lightheadedness, dizziness, nausea, or fainting, along with significant changes in blood pressure and/or heart rate. For vasovagal syncope, this typically involves a drop in blood pressure and often a slowing of heart rate. For POTS, it involves an abnormal increase in heart rate (at least 30 beats per minute or exceeding 120 bpm) within 10 minutes of standing, without significant blood pressure drop. The test helps physicians diagnose these conditions by reproducing symptoms in a controlled environment.

Key Points

• A positive tilt table test is defined as inducible presyncope or syncope associated with hypotension, with or without bradycardia 1
• The test is used to evaluate patients with syncope for nearly 3 decades and is an orthostatic stress test to assess the susceptibility of a vasovagal response to a postural change from a supine to an upright position 1
• The hemodynamic response to the tilt maneuver determines whether there is a cardioinhibitory, vasodepressor, or mixed response 1
• Tilt-table testing has been used to distinguish convulsive syncope from epilepsy in selected patients, with approximately 50% of patients with either questionable or drug-refractory epilepsy having positive tilt-table tests suggestive of a vasovagal etiology 1
• The test can also be useful to establish a diagnosis of pseudosyncope, with a normal blood pressure and heart rate, and a normal electroencephalogram (EEG) if such a recording is obtained, ruling out true syncope and most forms of epilepsy 1

Diagnosis and Treatment

• Treatment depends on the specific diagnosis but may include increased fluid and salt intake, compression garments, exercise programs, and medications such as fludrocortisone, midodrine, or beta-blockers 1
• The physiological basis involves autonomic nervous system dysfunction that impairs the body's normal compensatory mechanisms when changing positions, resulting in inadequate cerebral perfusion 1
• Tilt-table testing is safe, with no reported deaths during the test, but minor side effects are common, and include palpitations with isoproterenol and headache with nitroglycerin 1

From the Research

Tilt Table Test Indications

A positive tilt table test can indicate several conditions, including:

• Postural Orthostatic Tachycardia Syndrome (POTS) 2, 3, 4, 5, 6
• Orthostatic intolerance 2, 3, 4, 5, 6
• Autonomic dysfunction 2, 4, 6
• Neurocardiogenic syncope 6

Postural Orthostatic Tachycardia Syndrome (POTS)

POTS is characterized by:

• An increased heart rate of ≥30 bpm within 10 minutes of upright tilt 3, 4, 6
• Symptoms such as orthostatic intolerance, postural tachycardia, exercise intolerance, fatigue, dizziness, and near syncope 2, 3, 4, 5, 6
• Exaggerated response to isoproterenol infusions 6

Tilt Table Test Results

A positive tilt table test result is typically defined as:

• An increase in heart rate of ≥30 bpm within 10 minutes of upright tilt 3, 4, 6
• Reproduction of symptoms such as lightheadedness, dizziness, and near syncope 6
• Absence of profound hypotension 6

Diagnostic Considerations

The tilt table test should be used in conjunction with clinical history and other diagnostic evaluations to diagnose POTS and other conditions 2, 3, 4, 5, 6 Abbreviated tilt table testing may miss a substantial proportion of patients with POTS 3 The 30 bpm heart rate increase criterion may not be suitable for 30-minute tilt table testing 4