Postural Orthostatic Tachycardia Syndrome (POTS) and Orthostatic Hypotension

Diagnostic Criteria

A diagnosis of POTS requires an absence of orthostatic hypotension, defined as a systolic blood pressure drop of less than 20 mmHg within 10 minutes of standing, as recommended by the American College of Cardiology 1, 2
POTS is characterized by a sustained heart rate increase of ≥30 bpm within 10 minutes of standing or head-up tilt (≥40 bpm for individuals aged 12-19 years), in the absence of orthostatic hypotension, according to the American College of Cardiology 1, 2
The absence of other conditions explaining sinus tachycardia is required for a POTS diagnosis, as stated by the American College of Cardiology 1, 2
Orthostatic hypotension is diagnosed by a sustained decrease in systolic BP ≥20 mmHg, diastolic BP ≥10 mmHg, or systolic BP to <90 mmHg within 3 minutes of standing, as defined by the European Heart Journal 3

The 10-minute active stand test is recommended to assess for POTS, involving measurements of blood pressure and heart rate after 5 minutes of lying supine, immediately upon standing, and at 2, 5, and 10 minutes after standing, as suggested by the American College of Cardiology 2
Ambulatory rhythm monitoring should be considered to exclude arrhythmia and define the pattern of heart rate elevation in patients with suspected POTS, according to the American College of Cardiology 2
Active standing test for classical orthostatic hypotension (within 3 minutes) 3
Extended standing test or tilt-table test for delayed orthostatic hypotension (beyond 3 minutes) 3

Patients with POTS often experience symptoms of orthostatic intolerance, including lightheadedness, palpitations, tremulousness, generalized weakness, blurred vision, fatigue, and exercise intolerance, as reported by the American College of Cardiology 1
The tachycardia in POTS must last for more than 30 seconds and be accompanied by symptoms, as stated by the American College of Cardiology 2
Vasovagal syncope is triggered by a vasovagal reflex due to progressive blood pooling with final vasodepressive and/or cardioinhibitory pathways, as stated by the European Heart Journal 3
Orthostatic hypotension is characterized by impaired increase in total peripheral resistance and inadequate vasoconstriction, as reported by the European Heart Journal 3
Classical orthostatic hypotension: Immediate symptoms upon standing (dizziness, light-headedness, fatigue, visual disturbances) 3
Delayed orthostatic hypotension: Prolonged prodromal symptoms that develop gradually (dizziness, fatigue, visual/hearing disturbances, low back pain, neck or precordial pain) 3

Vasovagal syncope is more common in women and often presents in younger individuals, as reported by the European Heart Journal 3
Orthostatic hypotension is more common in elderly, frail patients, and is associated with autonomic failure, medication use, and specific triggers, as stated by the European Heart Journal 3
Risk factors for orthostatic hypotension include: autonomic failure (primary or secondary), severe volume depletion/hypovolemia, medication-induced (vasoactive drugs, diuretics, alpha-blockers), frailty, aging/frailty, incipient autonomic failure, Parkinsonism or diabetes (early stages), and multiple comorbidities 3

Both conditions benefit from physical counterpressure maneuvers (PCMs) during presyncope, with lower-body PCMs preferable to upper-body maneuvers, as recommended by the American Heart Association 4
Sitting or lying down is the priority first aid measure for both conditions, and PCMs should not be used when symptoms of heart attack or stroke accompany presyncope, as advised by the American Heart Association 4

Classical orthostatic hypotension is associated with increased mortality and cardiovascular disease prevalence 3
Impaired BP recovery after initial drop represents a negative prognostic factor in elderly patients 3
Delayed orthostatic hypotension may progress to classical orthostatic hypotension over time, especially in patients with Parkinsonism or diabetes 3