Postural Tachycardia Syndrome

Definition/diagnostic criteria Postural tachycardia syndrome (PoTS) is characterised by a significant increase in heart rate upon standing. According to the British Cardiovascular Society, PoTS is defined by a heart rate increase of 30 beats per minute (bpm) or more (or exceeding 120 bpm) within the first 10 minutes of standing or head-up tilt, in the absence of orthostatic hypotension. This should occur alongside a constellation of symptoms consistent with autonomic dysfunction that improve with recumbence.

Epidemiology The prevalence of PoTS is not fully established, partly due to under-recognition. It is estimated that it could affect up to 170 per 100,000 individuals in the UK, with a higher incidence in females and younger individuals. The peak incidence occurs in individuals aged between 15 and 50 years.

Diagnosis
Clinical features: The clinical features of PoTS are diverse and can include palpitations, dizziness, syncope, fatigue and exercise intolerance during the upright position, relieved by lying down. Non-orthostatic symptoms such as gastrointestinal disturbances, sleep abnormalities and bladder dysfunction may also be present, reflecting widespread autonomic involvement.

Investigations: Investigations to confirm PoTS include active standing tests or tilt-table testing to document the heart rate increase upon postural change. Additional tests may include 24-hour ambulatory blood pressure and heart rate monitoring to assess for diurnal variability and exclude other causes of tachycardia. Typical abnormalities found in patients with PoTS can include a high noradrenaline level upon standing, reflecting sympathetic overdrive.

Treatment Management of PoTS is multifaceted and involves a combination of non-pharmacological and pharmacological interventions. Non-pharmacological management includes increased fluid and salt intake, physical counter-manoeuvres, and graded exercise to improve orthostatic tolerance. Compression stockings may also be beneficial.

Pharmacological treatments involve drugs that increase blood volume, such as fludrocortisone, or beta-blockers like propranolol to control heart rate. Ivabradine is also suggested for patients who do not respond to or cannot tolerate beta-blockers. Other drugs, such as midodrine, which is a vasoconstrictor, can be used to increase peripheral resistance.

Prognosis The prognosis of PoTS is variable; while some individuals may experience improvement in symptoms, others may have a more chronic course. Early diagnosis and intervention can be associated with a better prognosis. There is no cure for PoTS, but many patients find their symptoms improve with treatment and lifestyle modifications.