What is the difference between Postural Orthostatic Tachycardia Syndrome (POTS) and orthostatic hypotension?

From the Guidelines

POTS (Postural Orthostatic Tachycardia Syndrome) and orthostatic hypotension are distinct conditions with different primary features, treatment approaches, and underlying mechanisms. In POTS, the primary feature is an abnormal increase in heart rate (at least 30 beats per minute or exceeding 120 bpm) within 10 minutes of standing, with minimal or no drop in blood pressure, as defined by the 2017 ACC/AHA/HRS guideline for the evaluation and management of patients with syncope 1. Patients with POTS experience symptoms such as dizziness, fatigue, brain fog, and palpitations due to this excessive heart rate response. On the other hand, orthostatic hypotension is characterized by a significant drop in blood pressure upon standing (at least 20 mmHg systolic or 10 mmHg diastolic within 3 minutes), which causes dizziness, lightheadedness, and potential fainting, as stated in the 2018 ESC guidelines for the diagnosis and management of syncope 1. The treatment approaches for these conditions also differ: POTS management focuses on increasing blood volume with salt and fluid intake, compression garments, exercise, and sometimes medications like beta-blockers, fludrocortisone, or midodrine, whereas orthostatic hypotension treatment includes hydration and salt, but may require different medications like fludrocortisone, midodrine, or droxidopa to raise blood pressure, as discussed in the 2017 ACC/AHA/HRS guideline 1. The underlying mechanisms of these conditions differ as well, with POTS involving dysregulation of the autonomic nervous system affecting heart rate control, and orthostatic hypotension resulting from inadequate vasoconstriction and blood pressure regulation when changing positions, as explained in the 2011 review on cardiovascular autonomic neuropathy in diabetes 1.

Some key points to consider when differentiating between POTS and orthostatic hypotension include:

• The presence of a significant drop in blood pressure in orthostatic hypotension, which is not typically seen in POTS
• The primary symptom of excessive heart rate response in POTS, which is not the primary feature of orthostatic hypotension
• The different treatment approaches for each condition, with POTS focusing on increasing blood volume and orthostatic hypotension focusing on raising blood pressure
• The distinct underlying mechanisms of each condition, with POTS involving autonomic nervous system dysregulation and orthostatic hypotension resulting from inadequate vasoconstriction and blood pressure regulation.

Overall, while both conditions can cause symptoms when standing, they have distinct features, treatment approaches, and underlying mechanisms, and accurate diagnosis and treatment require a thorough understanding of these differences, as emphasized by the 2017 ACC/AHA/HRS guideline 1 and the 2018 ESC guidelines for the diagnosis and management of syncope 1.

From the Research

Definition and Diagnosis

• Orthostatic hypotension is defined as a decrease in blood pressure of 20 mm Hg or more systolic or 10 mm Hg or more diastolic within three minutes of standing from the supine position or on assuming a head-up position of at least 60 degrees during tilt table testing 2.
• Postural orthostatic tachycardia syndrome (POTS) is a clinically heterogeneous disorder with multiple contributing pathophysiologic mechanisms manifesting as symptoms of orthostatic intolerance in the setting of orthostatic tachycardia (increase in heart rate by at least 30 beats per minute upon assuming an upright position) without orthostatic hypotension 3.

Symptoms and Prevalence

• Symptoms of orthostatic hypotension include headache, lightheadedness, shoulder and neck pain, visual disturbances, dyspnea, and chest pain 2.
• Patients with POTS report dizziness, lightheadedness, weakness, blurred vision, and fatigue upon standing 4.
• The prevalence of orthostatic hypotension in the community setting is 20% in older adults and 5% in middle-aged adults, while POTS is a less common condition, affecting mostly females of child-bearing age 2, 5.

Treatment and Management

• Treatment goals for orthostatic hypotension are reducing symptoms and improving quality of life, with initial treatment focusing on the underlying cause and adjusting potentially causative medications 2.
• For POTS, treatment approaches are individualized based on the underlying pathophysiologic mechanism, with lifestyle modifications, such as increased fluid and salt intake, compression garment use, and physical reconditioning, being first-line treatments 6.
• Pharmacologic therapies for POTS are primarily used to manage specific symptoms, with beta-blockers being effective for hyperadrenergic POTS and agents that enhance vascular tone, such as pyridostigmine and midodrine, being used for neuropathic POTS 6.