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Health condition · Clinically reviewed

Cardiac arrhythmia, the full family of abnormal heart rhythms and how they are treated.

From harmless ectopics to atrial fibrillation, inherited channelopathies and ventricular tachycardia, modern UK care combines accurate diagnosis, catheter ablation, devices and lifestyle change.

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Why trust this guide

  • 01

    Clinically reviewed

    Written by our editorial team and reviewed by a UK-registered clinician before publication.

  • 02

    Sourced from guidance

    Checked against ESC 2020 to 2023 guidance, NICE, BHF and specialist society standards.

  • 03

    Current for 2026

    Covers modern rhythm care, catheter ablation, leadless pacing, subcutaneous ICDs and inherited cardiac conditions.

Key facts

Cardiac arrhythmia at a glance.

The essentials in plain English, from the main groups of abnormal rhythm to the tests, procedures and devices used in modern UK care.

  • What it is

    An umbrella term for abnormal heart rhythms, ranging from harmless ectopy to life-threatening ventricular tachycardia and fibrillation.

  • Main groups

    Bradyarrhythmias (too slow), tachyarrhythmias (too fast, supraventricular or ventricular), channelopathies, drug-induced and electrolyte-driven rhythms.

  • Common features

    Palpitations, presyncope, syncope, breathlessness, fatigue, chest pain, sometimes polyuria in AVNRT, sometimes collapse.

  • Foundation test

    The 12-lead ECG, supported by ambulatory monitoring, echo and, when indicated, cardiac MRI and electrophysiology study.

  • Modern treatment

    Rate control, rhythm control, catheter ablation, pacemakers, ICDs and, in AF, anticoagulation guided by CHA2DS2-VASc.

  • Inherited rhythms

    Long QT, Brugada, CPVT, ARVC and progressive conduction disease need specialist ICC clinic input and cascade family screening.

Why this guide matters

Right diagnosis first, then the right rhythm plan.

The umbrella of arrhythmia hides very different problems. Getting the label right shapes everything: rate control, rhythm control, ablation, anticoagulation, devices and family screening.

  • Bradyarrhythmias

    Slow rhythms include sinus bradycardia, sinus node dysfunction (sick sinus syndrome), first, second and third degree AV block, bundle branch and fascicular blocks. See our companion guide at /conditions/bradycardia/ for detail.

  • Tachyarrhythmias

    Fast rhythms split into supraventricular (sinus tachycardia, AVNRT, AVRT/WPW, atrial tachycardia, atrial flutter, AF, multifocal atrial tachycardia) and ventricular (PVCs, VT, torsades de pointes, VF, idioventricular).

  • Channelopathies and inherited

    Long QT (LQT1 to LQT15), short QT, Brugada, CPVT, early repolarisation, progressive cardiac conduction disease and ARVC need specialist inherited cardiac conditions input and cascade family screening.

  • Drug-induced and acquired

    QT-prolonging medicines, illicit stimulants and severe illness can all provoke rhythm disturbance. Reviewing every drug on the chart is a first-line intervention.

  • Electrolyte-driven

    Hypokalaemia, hyperkalaemia, hypocalcaemia, hypercalcaemia, hypomagnesaemia and acidosis can all trigger dangerous rhythms. Correction is often curative.

How the diagnosis is made

From first palpitation to a clear rhythm plan.

The path a UK GP or cardiologist typically follows, from history and ECG through ambulatory monitoring, imaging and, when indicated, an electrophysiology study.

  1. 01

    Assessing

    History and triggers

    Character, duration, onset, associated symptoms, family history of sudden death, medications, caffeine, alcohol and stress.

  2. 02

    Assessing

    Examination

    Pulse, blood pressure, JVP, murmurs and heart-failure signs shape how urgent the workup is.

  3. 03

    Assessing

    12-lead ECG

    The foundation test. Intervals, morphology, delta wave in WPW, QT length and Brugada pattern all matter.

  4. 04

    Confirming

    Ambulatory monitoring

    24 to 72 hour Holter, 7 to 14 day patch (Zio, Bardy Diagnostics), event recorder or implantable loop recorder for infrequent syncope.

  5. 05

    Confirming

    Imaging and provocation

    Echo for structural heart disease, cardiac MRI for cardiomyopathy, fibrosis, ARVC or sarcoid, and exercise testing for inducible arrhythmia.

  6. 06

    Confirming

    Bloods and tilt testing

    Electrolytes, TFT, troponin, BNP, toxicology and selective genetic panels. Tilt-table and carotid sinus massage for reflex syncope.

  7. 07

    Preparing

    EP study and specialist review

    Electrophysiology study for accessory pathways, risk stratification and inducibility, in an arrhythmia or inherited cardiac conditions clinic.

Typical timeline: weeks for common rhythms, longer where infrequent syncope or inherited disease is suspected.

Symptoms

What an arrhythmia can feel like.

Rhythms feel very different from person to person. Some cause dramatic palpitations, others only fatigue, and some are silent until spotted on a routine ECG or smartwatch.

  • Palpitations

    Fluttering, thumping or racing in the chest, neck or throat, sometimes with a defined start and stop.

  • Presyncope and syncope

    Light-headedness, greying out or a full blackout, especially on exertion or without warning, needs prompt review.

  • Breathlessness and fatigue

    A poorly controlled rhythm reduces cardiac output, causing effort intolerance and unexplained tiredness.

  • Chest pain and pressure

    Sustained fast rhythms can trigger angina, particularly with underlying coronary disease.

  • Polyuria in AVNRT

    Sustained supraventricular tachycardia can prompt atrial natriuretic peptide release and increased urine output.

  • Asymptomatic ECG findings

    Some rhythms are picked up incidentally on a routine ECG, pre-op check or smartwatch alert.

  • Smartwatch alerts

    Apple Watch, KardiaMobile and Fitbit rhythm strips increasingly flag AF and other rhythms before symptoms are clear.

  • Red flag, haemodynamic collapse

    Syncope on exertion, family history of sudden cardiac death or witnessed cardiac arrest needs emergency assessment.

Treatment

How arrhythmia is treated in the UK.

Aligned with ESC 2020 to 2023 guidance: fix the underlying driver, choose rate or rhythm control, offer catheter ablation where it fits, protect from stroke and, when needed, implant a device.

  • Treat the underlying cause

    Coronary disease, heart failure, electrolyte disturbance, thyroid disease and offending drugs are corrected first wherever possible.

  • Rate control

    Beta-blockers, non-dihydropyridine calcium channel blockers and digoxin slow ventricular response in AF and other supraventricular rhythms.

  • Rhythm control

    Cardioversion and antiarrhythmics (flecainide, propafenone, sotalol, amiodarone, dronedarone) restore or maintain sinus rhythm.

  • Catheter ablation

    Highly effective for many SVTs, atrial flutter and AF. Pulmonary vein isolation is the cornerstone AF procedure at specialist EP centres.

  • Anticoagulation in AF

    A DOAC is first-line, warfarin for valvular AF, with stroke risk guided by CHA2DS2-VASc and bleeding risk by HAS-BLED.

  • Pacemakers and conduction pacing

    For symptomatic bradycardia and heart block. Options include dual-chamber, leadless Micra and His or left bundle branch area pacing.

  • ICDs and CRT

    Subcutaneous or transvenous ICDs for VT and VF, CRT-D for heart failure with LBBB, and wearable defibrillators (LifeVest) as a bridge.

  • Lifestyle, genetics and MDT

    Weight, alcohol, caffeine, sleep, OSA treatment and smoking cessation, plus cascade screening and specialist ICC and charity support.

Practical extras

The details that make a rhythm plan work in real life.

DVLA, occupational and sports guidance vary by rhythm and treatment; genetic counselling and cascade family testing matter in inherited disease; and MDT care that includes cardiology, EP, heart failure, specialist ICC clinics, specialist nurses and charities such as the BHF, Cardiomyopathy UK, SADS UK and CRY UK often makes the biggest long-term difference.

What this guide is based on

The sources behind every claim on this page.

UK national guidance and international 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 history and can tell you which parts apply to you. If in doubt, get seen. If your symptoms are severe or you black out, call 999.

  • European Society of Cardiology. Guidelines on supraventricular tachycardia, atrial fibrillation, ventricular arrhythmias and cardiac pacing (2020 to 2023).

  • NICE. Atrial fibrillation: diagnosis and management (NG196) and transient loss of consciousness (CG109).

  • British Heart Foundation. Patient information on arrhythmias, pacemakers and ICDs.

  • Resuscitation Council UK. Advanced Life Support guidance on peri-arrest arrhythmias.

  • DVLA. Assessing fitness to drive: cardiovascular disorders.

Red flags

When an arrhythmia needs urgent attention.

Many rhythm problems are manageable in primary care or an outpatient clinic. These are the situations that are not, and where a specialist opinion, sometimes same-day, is needed.

  • Syncope on exertion

    Blackout during exercise may signal structural heart disease, ischaemia or a channelopathy and needs urgent cardiology review.

  • Family history of sudden cardiac death

    A first-degree relative under 40 with unexplained SCD warrants referral to an inherited cardiac conditions clinic and cascade screening.

  • Wide-complex tachycardia

    Assume ventricular tachycardia until proven otherwise. Needs emergency assessment and monitored care.

  • Sustained palpitations with collapse

    A rhythm that causes loss of consciousness or near-collapse is not benign, whatever the surface ECG shows in clinic.

  • New heart failure with an arrhythmia

    Uncontrolled fast rhythms can drive tachycardia-induced cardiomyopathy. Prompt rate or rhythm control is important.

  • QT-prolonging medication concerns

    Starting a new drug and developing palpitations, syncope or polymorphic VT features needs urgent medication review.

  • Post-arrest survivor

    Anyone resuscitated from cardiac arrest needs full arrhythmia workup, imaging and consideration of ICD therapy.

  • Pregnancy and known arrhythmia

    Pregnancy changes drug choices and monitoring needs. Combined cardiology and obstetric input is essential.

  • Pacemaker or ICD malfunction

    Shocks, syncope or device alerts need same-day device-clinic assessment.

Living with it

A rhythm condition, with a plan you can follow.

Four things that make the biggest day-to-day difference: knowing your triggers, treating sleep apnoea, staying active safely and living confidently with a device if you need one.

A quiet reminder

Consistency and follow-up matter more than any single scan.

Steady habits, regular device checks and honest reporting of symptoms help your team fine-tune your plan year by year.

  1. 01 Triggers

    Know your triggers

    Alcohol, caffeine, dehydration, poor sleep and stress all provoke arrhythmias. Small changes often reduce episode frequency.

  2. 02 Sleep

    Treat sleep apnoea

    Obstructive sleep apnoea is a major driver of AF and other rhythms. Screening and CPAP can transform control.

  3. 03 Activity

    Stay active, safely

    Moderate regular exercise is protective. Follow specialist advice on intensity and any Bethesda or DVLA restrictions.

  4. 04 Devices

    Live well with a device

    Pacemakers and ICDs are compatible with most daily life. Your device clinic will explain scanning, travel and driving rules.

Frequently asked

Everything we get asked about cardiac arrhythmia.

Quick answers on rhythms, tests, catheter ablation, anticoagulation and inherited arrhythmias.

  • What is a cardiac arrhythmia?

    Any abnormal heart rhythm. That includes rhythms that are too slow (bradyarrhythmias), too fast (supraventricular or ventricular tachyarrhythmias), or irregular such as atrial fibrillation. It also includes inherited channelopathies like long QT, Brugada and CPVT, and rhythms driven by drugs or electrolyte imbalance.

  • Are palpitations always serious?

    No. Most palpitations are benign ectopic beats or sinus tachycardia. Warning features include syncope, presyncope, palpitations with chest pain, exertional symptoms, a family history of sudden death or a known structural heart problem. These need prompt assessment.

  • How is an arrhythmia diagnosed?

    The 12-lead ECG is the foundation. Ambulatory monitoring (Holter, patch, event recorder or implantable loop recorder) captures rhythms during symptoms. Echo, cardiac MRI, exercise testing and, when indicated, an electrophysiology study add detail.

  • When is catheter ablation an option?

    For many supraventricular tachycardias, atrial flutter and paroxysmal or persistent AF, catheter ablation can be highly effective. Decisions are made at specialist EP centres and depend on rhythm type, symptoms, structural findings and patient preference.

  • Do I need blood thinners with AF?

    It depends on your stroke risk, usually assessed with the CHA2DS2-VASc score, balanced against bleeding risk with HAS-BLED. DOACs are first-line in non-valvular AF. Warfarin is preferred in mechanical valves and moderate to severe mitral stenosis.

  • What is an inherited arrhythmia and why does it matter?

    Some rhythms, such as long QT syndrome, Brugada syndrome, CPVT and ARVC, are caused by inherited gene changes. They can affect several family members and, rarely, cause sudden cardiac death. Specialist inherited cardiac conditions clinics offer diagnosis, cascade family screening and genetic counselling.

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