What degree of systolic blood pressure drop is required for a diagnosis of Postural Orthostatic Tachycardia Syndrome (POTS)?

Systolic Blood Pressure Change in POTS Diagnosis

For a diagnosis of Postural Orthostatic Tachycardia Syndrome (POTS), there should be an absence of orthostatic hypotension, which means systolic blood pressure should NOT drop by 20 mmHg or more within 10 minutes of standing. 1

Diagnostic Criteria for POTS

POTS is defined by the following criteria:

1. Sustained heart rate increase ≥30 bpm within 10 minutes of standing or head-up tilt (≥40 bpm for individuals aged 12-19 years)
2. Absence of orthostatic hypotension (no sustained systolic blood pressure drop ≥20 mmHg)
3. Frequent symptoms of orthostatic intolerance during standing that improve when returning to supine position
4. Duration of symptoms for at least 3 months
5. Absence of other conditions explaining sinus tachycardia

Blood Pressure Parameters in POTS vs. Orthostatic Hypotension

POTS

• Heart rate increases ≥30 bpm (≥40 bpm in adolescents)
• Systolic BP does NOT drop by ≥20 mmHg
• Diastolic BP does NOT drop by ≥10 mmHg

Classical Orthostatic Hypotension

• Sustained decrease in systolic BP ≥20 mmHg
• Sustained decrease in diastolic BP ≥10 mmHg
• Or systolic BP falling to <90 mmHg
• Occurs within 3 minutes of standing 2

Testing for POTS

The 10-minute active stand test is recommended to assess for POTS:

• Measure blood pressure and heart rate after 5 minutes of lying supine
• Measure immediately upon standing
• Continue measurements at 2,5, and 10 minutes after standing 1

Clinical Pearls and Pitfalls

• Important distinction: POTS specifically requires the absence of orthostatic hypotension, which differentiates it from other forms of orthostatic intolerance 1
• In patients with supine hypertension, a larger drop in BP (≥30 mmHg) may be considered significant for diagnosing orthostatic hypotension, not POTS 2
• The tachycardia in POTS must last for more than 30 seconds and be accompanied by symptoms 1
• The patient should stand quietly for the full 10 minutes during testing, as heart rate increases may take time to develop 1
• Ambulatory rhythm monitoring should be considered to exclude arrhythmia and define the pattern of heart rate elevation 1

Common Symptoms of POTS

• Lightheadedness
• Palpitations
• Tremulousness
• Generalized weakness
• Blurred vision
• Fatigue
• Exercise intolerance 1, 3

Remember that POTS is a heterogeneous syndrome with multiple potential pathophysiologic mechanisms, including limited autonomic neuropathy, hyperadrenergic state, hypovolemia, venous pooling, and deconditioning 4. The key diagnostic feature that distinguishes it from orthostatic hypotension is the maintenance of blood pressure despite the significant heart rate increase upon standing.