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Health condition · Clinically reviewed

Heart arrhythmia, from ectopic beats to inherited rhythm disorders.

A UK guide to atrial fibrillation, SVT, ventricular arrhythmia, heart block and inherited channelopathies - how theyre diagnosed, treated and lived with.

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Why trust this guide

  • 01

    Clinically reviewed

    Written by our editorial team and reviewed by a UK cardiologist before publication.

  • 02

    Sourced from guidance

    Checked against ESC, NICE, BHF and Cardiomyopathy UK guidance you can see at the end.

  • 03

    Current for 2026

    Reflects modern UK arrhythmia care including catheter ablation, ICDs and inherited cardiac conditions clinics.

Key facts

Heart arrhythmia at a glance.

The essentials in plain English - what it is, the main groups, and how UK cardiology treats each today.

  • What it is

    A group of conditions in which the hearts electrical rhythm becomes too fast, too slow or irregular.

  • Supraventricular

    Arising above the ventricles - atrial fibrillation, atrial flutter, AVNRT, AVRT (WPW) and atrial tachycardia.

  • Ventricular

    Arising from the ventricles - ventricular tachycardia, ventricular fibrillation and ventricular ectopy.

  • Bradyarrhythmia

    Sinus bradycardia, sick sinus syndrome and 1st, 2nd and 3rd degree heart block.

  • Inherited

    Channelopathies and inherited cardiomyopathies - long QT, Brugada, CPVT, short QT and ARVC.

  • Emergency

    Ventricular fibrillation, sustained VT and torsades de pointes are life-threatening and need urgent care.

Why this guide matters

Rhythm disorders are treatable, and often curable.

The three principles below shape the whole of modern UK arrhythmia care.

  • The ECG is the starting point

    A 12-lead ECG combined with ambulatory monitoring identifies most rhythms - and rules out ischaemia, long QT and pre-excitation.

  • Ablation has changed the field

    Catheter ablation is curative for most SVTs and a mainstay for AF, atrial flutter and selected VT.

  • Inherited disease needs family review

    Long QT, Brugada, CPVT and ARVC run in families - cascade screening in an ICC clinic saves lives.

How the diagnosis is made

From first palpitation to a clear rhythm plan.

The steps a UK GP or cardiologist will normally follow, in order - so you know what to expect and why.

  1. 01

    Assessing

    History and triggers

    Palpitations, syncope, breathlessness, dizziness and chest pain - alongside caffeine, alcohol, medications and stress.

  2. 02

    Assessing

    Family history

    Sudden cardiac death under 40, unexplained drowning, epilepsy-like events or known inherited heart disease raises suspicion of an inherited arrhythmia.

  3. 03

    Assessing

    12-lead ECG

    The single most useful first test - identifies rate, rhythm, conduction, QT interval, pre-excitation and ischaemia.

  4. 04

    Confirming

    Ambulatory monitoring

    Holter, patch or implantable loop recorder ( /treatments/implantable-loop-recorder/ ) captures intermittent rhythms over days, weeks or years.

  5. 05

    Confirming

    Echocardiogram and cardiac MRI

    Assesses structural heart disease, ejection fraction and cardiomyopathy - MRI is specialist commissioned for suspected ARVC and infiltrative disease.

  6. 06

    Preparing

    Electrophysiology study

    Invasive mapping of the electrical circuit - specialist commissioned, usually combined with catheter ablation where appropriate.

  7. 07

    Preparing

    Genetic testing and cascade

    For suspected inherited arrhythmia - via a specialist commissioned inherited cardiac conditions (ICC) clinic such as Barts, Royal Brompton or Papworth.

Typical timeline: a first ECG to a confirmed plan in weeks, longer for inherited disease.

Symptoms

What arrhythmia actually feels like.

Palpitations, faints, breathlessness and dizziness - and the red-flag features that need same-day cardiology.

  • Palpitations

    A sensation of racing, pounding, fluttering or skipping beats - see /conditions/heart-palpitations/ for the full guide.

  • Syncope and pre-syncope

    Fainting or near-fainting during exertion or without warning - see /conditions/fainting/. A red flag for VT and inherited arrhythmia.

  • Breathlessness

    Dyspnoea on exertion or at rest, particularly with sustained tachyarrhythmia or heart block.

  • Chest pain or tightness

    Can accompany fast arrhythmia or reflect underlying ischaemic heart disease.

  • Dizziness and light-headedness

    Common with bradyarrhythmia and paroxysmal SVT - worse on standing or after exertion.

  • Cardiac arrest

    Sudden collapse with no pulse - VF or pulseless VT until proven otherwise. See /conditions/cardiac-arrest/.

  • Reduced exercise tolerance

    A subtler sign - especially in bradyarrhythmia, sick sinus syndrome and persistent AF.

  • Red flag - exertional syncope

    Syncope during exercise, a family history of sudden death or a broad-complex tachycardia deserves urgent cardiology input.

Treatment

How arrhythmia is treated in the UK.

Rate and rhythm control for AF, ablation for SVT, pacing for bradycardia, ICDs for high-risk ventricular disease and beta-blockade for inherited channelopathy.

  • Rate and rhythm control (AF)

    Beta-blockers, calcium-channel blockers, digoxin or antiarrhythmics - alongside anticoagulation. See /conditions/atrial-fibrillation/.

  • Vagal manoeuvres and adenosine

    First-line for narrow-complex SVT - Valsalva, carotid massage or IV adenosine to terminate the circuit.

  • Catheter ablation

    Definitive therapy for many SVTs, AF, atrial flutter and selected VT - see /treatments/catheter-ablation-electrophysiology/.

  • Pacemaker implantation

    For symptomatic bradycardia, sick sinus syndrome and 2nd or 3rd degree heart block - see /treatments/pacemaker-implantation/.

  • Implantable cardioverter defibrillator

    Primary or secondary prevention for VT, VF and inherited arrhythmia at high risk - see /treatments/subcutaneous-icd/.

  • Beta-blockers for inherited disease

    Foundational for long QT and CPVT - reduces adrenergic triggers. Specialist commissioned in ICC clinics.

  • Antiarrhythmic drugs

    Amiodarone, sotalol, flecainide and dronedarone - selected by rhythm type and structural heart disease.

  • Emergency defibrillation

    For VF, pulseless VT and torsades - immediate CPR and DC shock. Follow up in ICU and specialist commissioned electrophysiology review.

What this guide is based on

The sources behind every claim on this page.

UK national guidance and specialist society standards, current at the time of last review.

Key references

Guidelines and standards we relied on.

A quiet reminder

This guide is for information, not medical advice.

Your GP or cardiologist knows your heart and history and can tell you which parts apply to you. If in doubt, get seen.

  • European Society of Cardiology (ESC). Guidelines for supraventricular tachycardia, ventricular arrhythmias and atrial fibrillation.

  • NICE. Atrial fibrillation: diagnosis and management (NG196).

  • British Heart Foundation (BHF). Patient information on heart rhythm problems.

  • Cardiomyopathy UK. Information on ARVC and inherited cardiomyopathy.

  • Resuscitation Council UK. Advanced life support guidelines.

Red flags

When arrhythmia is an emergency.

Most palpitations are benign. These are the features that arent - and where urgent hospital assessment is essential.

  • Cardiac arrest

    Sudden collapse without a pulse - call 999, start CPR and use an AED immediately. Almost always VF or pulseless VT.

  • Exertional syncope

    Fainting during exercise may signal VT, hypertrophic cardiomyopathy or long QT - needs urgent cardiology assessment.

  • Family history of sudden death

    Unexplained death under 40 in a first-degree relative warrants specialist commissioned inherited cardiac conditions clinic review.

  • Broad-complex tachycardia

    Assume ventricular tachycardia until proven otherwise - urgent hospital assessment.

  • Torsades de pointes

    Polymorphic VT on a long QT background - stop QT-prolonging drugs, correct hypokalaemia and get specialist commissioned input.

  • Complete heart block

    Third degree AV block with symptoms is a pacing emergency - see /conditions/heart-block/.

  • WPW with atrial fibrillation

    Pre-excited AF is a high-risk combination - avoid AV nodal blockers and refer for urgent electrophysiology review.

  • Syncope with structural heart disease

    Any faint in the context of prior MI, cardiomyopathy or reduced ejection fraction is high risk.

  • Pregnancy with arrhythmia

    Palpitations in pregnancy usually benign - but new sustained arrhythmia needs joint cardiology and obstetric review.

Living with it

A treatable condition, with a clear ladder.

Four things that make the biggest difference day to day - knowing your triggers, taking medication reliably, involving your family and learning CPR.

A quiet reminder

Consistency beats intensity, every time.

Steady habits, kept up for months, do more than a heroic week that doesnt last.

  1. 01 Triggers

    Know your triggers

    Caffeine, alcohol, poor sleep and stress all lower the threshold for arrhythmia. Small changes often reduce episodes.

  2. 02 Medication

    Take medication as prescribed

    Rate control, antiarrhythmics and anticoagulation only work when taken consistently - missed doses raise the risk of stroke and recurrence.

  3. 03 Family

    Cascade screening matters

    For inherited arrhythmia, first-degree relatives should be reviewed in a specialist commissioned ICC clinic.

  4. 04 CPR

    Learn CPR

    Family CPR training and knowing where local defibrillators are placed saves lives - particularly for households living with inherited arrhythmia.

Frequently asked

Everything we get asked about arrhythmia.

Quick answers on palpitations, atrial fibrillation, inherited arrhythmia, ICDs and ablation.

  • What is a heart arrhythmia?

    An arrhythmia is any abnormal heart rhythm - too fast, too slow or irregular. It can arise from the atria (supraventricular), the ventricles (ventricular) or from problems with the conduction system (bradyarrhythmia and heart block). Some are benign, some are life-threatening.

  • Are palpitations always serious?

    No. Most palpitations reflect benign ectopic beats or sinus tachycardia. But palpitations with syncope, chest pain, breathlessness or a family history of sudden cardiac death need prompt cardiology assessment and often ambulatory monitoring.

  • What is the most common arrhythmia?

    Atrial fibrillation. It affects around 2 percent of UK adults, and rises steeply with age. It needs rate or rhythm control and anticoagulation to reduce stroke risk - see our full guide at /conditions/atrial-fibrillation/.

  • What is an inherited arrhythmia?

    A group of channelopathies and cardiomyopathies that run in families - including long QT, Brugada, CPVT, short QT and ARVC. Diagnosis usually needs an ECG, echo, cardiac MRI and genetic testing via a specialist commissioned inherited cardiac conditions clinic.

  • When is an ICD needed?

    An implantable cardioverter defibrillator is offered for secondary prevention after aborted sudden death, and for primary prevention in selected high-risk groups - severe left ventricular dysfunction, ARVC, hypertrophic cardiomyopathy and certain channelopathies. See /treatments/subcutaneous-icd/.

  • Can catheter ablation cure my arrhythmia?

    For many supraventricular tachycardias - AVNRT, AVRT and atrial flutter - ablation is curative in over 95 percent of cases. For atrial fibrillation and ventricular tachycardia, ablation reduces burden and symptoms, sometimes dramatically. See /treatments/catheter-ablation-electrophysiology/.

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