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Educational draft · awaiting clinical reviewUse Rapid for revision, not patient-care decisions. Check current national and local guidance and the BNF or BNFC before acting.

Postural tachycardia syndrome and inappropriate sinus tachycardia

Cardiology · UK scope · Sources checked 27 Aug 2026 · Clinical review pending

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Escalate

PoTS and IST are not diagnoses to assign during collapse with ongoing chest pain, severe breathlessness, focal neurology, major bleeding, sustained non-sinus tachyarrhythmia or haemodynamic compromise. Use emergency assessment and treat the underlying cause; call 999 for persistent collapse or severe symptoms.

Synopsis

Differentiate PoTS from inappropriate sinus tachycardia and physiological sinus tachycardia, perform reproducible orthostatic testing, and use staged non-drug and specialist off-label treatment safely.

  • Adult PoTS requires chronic orthostatic symptoms plus a sustained heart-rate rise of at least 30 beats/min within 10 minutes of standing, without classical orthostatic hypotension and without another cause.
  • Record supine rest, HR and BP together, then serial standing measurements to 10 minutes; one smartwatch peak or a dehydrated bedside pulse is not diagnostic.
  • IST is sinus rhythm that is persistently and inappropriately fast, typically resting over 100 beats/min with a 24-hour mean over 90 beats/min, after fever, anaemia, thyroid disease, drugs and other causes are excluded.
  • PoTS is posture-linked; IST is also fast at rest and with minimal exertion. They can overlap, but focal atrial tachycardia and other SVTs must first be excluded.
  • Start PoTS management with education, adequate fluid, clinician-agreed salt, compression and a graded recumbent-to-upright conditioning programme.
  • Salt loading is not universal: avoid or modify it in hypertension, heart failure, kidney disease or pregnancy and consider dietetic/specialist input.
  • There is no UK-licensed medicine specifically for PoTS or IST; midodrine, fludrocortisone and ivabradine are specialist-selected off-label options with phenotype-specific monitoring.
  • Routine sinus-node ablation for IST is not recommended because recurrence, autonomic symptoms and pacemaker dependence can outweigh benefit.

Key red flags

Red-flag presentation

Exertional syncope, family history of young sudden death, abnormal cardiac examination/ECG, sustained broad-complex rhythm or major desaturation requires urgent cardiac evaluation, not reassurance as dysautonomia.

Investigation priorities

01
10-minute active stand testFirst step

Reproduce orthostatic symptoms while measuring HR and BP after adequate supine rest and serially upright.

Management branches

first-assessmentFirst assessment of sinus tachycardia

Palpitations, dizziness or fatigue occur with a documented fast sinus rate.

  1. Check ABCDE/red flags, 12-lead ECG, medication/substance exposure, volume status, infection, bleeding, pregnancy where relevant and cardiopulmonary examination.
  2. Obtain FBC/ferritin, renal/electrolyte, glucose and thyroid tests plus targeted tests suggested by the history; treat a reversible driver first.
  3. If symptoms are posture-linked, perform a standardised 10-minute stand with paired HR/BP and symptom recording; if tachycardia is present at rest, arrange ambulatory ECG.
  4. Refer to cardiology/autonomic expertise when disabling, diagnostically uncertain, associated with syncope or an abnormal ECG/examination, or unresponsive to initial measures.

Key medicines

MidodrineSpecialist off-label PoTS use: 2.5 mg orally three times daily initially, titrated at intervals of more than 3 days or weekly to response; usual maximum 10 mg three times daily (30 mg/day). Take the final dose at least 4 hours before bed.Unlicensed for PoTS. Check supine/sitting/standing BP, renal and liver function; avoid in hypertension, severe organic heart disease, urinary retention, acute/severe renal disease and pregnancy. Stop if supine hypertension persists.
FludrocortisoneSpecialist off-label use commonly starts at 0.05–0.1 mg orally once daily; the SmPC adult replacement range is 0.05–0.3 mg once daily, but PoTS is not a licensed indication.Monitor supine/standing BP, weight, oedema, sodium and potassium and review salt intake; avoid uncontrolled hypertension/heart failure and use the lowest effective dose. Do not stop prolonged therapy abruptly without advice.
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Sources and review status8 sources · checked 27 Aug 2026 · clinical review pending+
Sources

Sources and review status

National guidance is shown before implementation-dependent detail. Typical adult dose examples remain subject to patient factors, contraindications and the live BNF or specialist protocol. Source check completed 27 Aug 2026; clinical approval remains outstanding.

  • NHS: Postural tachycardia syndromeSymptoms, diagnostic route and first-line lifestyle treatment.
  • NHS BNSSG ICB: PoTS clinical pathwayAdult stand criterion and specialist medicine context.
  • ESC: 2019 supraventricular tachycardia guidelinePoTS exercise/fluid/salt options and IST treatment recommendations.
  • NHS South West London ICB: MidodrineUnlicensed status, specialist initiation, exact dosing and monitoring.
  • eMC: Fludrocortisone acetate 0.1 mg tablets SmPCLicensed replacement-dose boundaries and steroid safety used to frame off-label PoTS prescribing.
  • eMC: Propranolol 10 mg tablets SmPCLicensed arrhythmia dose boundaries and contraindications used to frame off-label PoTS prescribing.
  • eMC: Midodrine 2.5 mg tablets SmPCLicensed orthostatic-hypotension dosing and safety boundaries contrasted with specialist off-label PoTS use.
  • eMC: Ivabradine 5 mg SmPCLicensed dose boundaries, interactions and safety used to frame off-label specialist use.

Editorial contact: Doctor’s Passport editorial team. Source-check date is separate from clinical approval. Report a content problem · Content changes

Authoring stateRapid draftClinical stateAwaiting reviewJurisdictionUnited Kingdom