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OverviewAetiologyPathophysiologyClinical features and red flagsInvestigationsDifferential diagnosisManagementComplicationsMonitoring and follow-upSpecial situationsCommon pitfallsQuestionsSources
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Educational draft · awaiting clinical reviewThe full textbook explains uncertainty but does not replace live national or local guidance, specialist advice, or current prescribing information.

Palpitations and rhythm monitoring

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

RapidFull
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Time-critical presentation

Call 999 or arrange emergency admission for ongoing palpitations with syncope, significant breathlessness, chest pain, haemodynamic compromise, ventricular tachycardia or another immediately dangerous ECG finding.

Overview

Assess palpitations safely, identify high-risk presentations and choose monitoring that is long enough to capture the symptom-rhythm correlation.

The central diagnostic task is to link the patient's sensation to an ECG rhythm. Descriptions such as racing, fluttering, pounding or a missed beat can suggest mechanisms, but none is sufficiently specific to replace rhythm documentation.

Risk comes from context as much as rate. Palpitations during exertion, palpitations followed by syncope, inherited-arrhythmia clues and evidence of structural heart disease justify faster specialist assessment even when the clinic ECG is normal.

Monitoring yield rises when the recording window matches symptom frequency. Repeating short Holters for monthly symptoms is usually less useful than selecting a longer patient-activated or continuous device at the outset.

Key points

  • Palpitations describe awareness of the heartbeat; they are a symptom, not a rhythm diagnosis.
  • Record a 12-lead ECG during symptoms whenever possible, but a normal resting ECG does not exclude an intermittent arrhythmia.
  • Match monitor duration to event frequency: 24-48 hour Holter for symptoms at least daily, longer event or patch monitoring for less frequent episodes, and an implantable loop recorder for rare but concerning events.
  • Syncope, exertional onset, structural heart disease, an abnormal baseline ECG or a family history of sudden cardiac death before 40 years raises concern.
  • Ask the patient to mark symptoms and activities; a tracing without contemporaneous symptoms may not explain the complaint.
  • Check reversible contributors such as anaemia, thyroid disease, electrolyte disturbance, infection, pregnancy, stimulants and medicines.
  • Isolated ectopic beats in a structurally normal heart often need explanation and trigger reduction rather than antiarrhythmic treatment.

Aetiology

01

Supraventricular tachyarrhythmia

Atrial fibrillation, atrial flutter and re-entrant supraventricular tachycardia produce rapid or irregular ventricular activation. Accessory pathways, atrial disease and increasing age alter susceptibility, while episodes may remain intermittent.

02

Ectopy and ventricular arrhythmia

Premature atrial or ventricular beats commonly create a skipped-beat sensation followed by a thump. Structural heart disease, previous infarction or inherited electrical disease increases concern for sustained ventricular arrhythmia.

03

Physiological or systemic sinus tachycardia

Exercise, fever, pain, dehydration, anaemia, pregnancy, hypoglycaemia or thyrotoxicosis increase sympathetic drive or circulatory demand. The sinus rate rises in response, making the underlying driver the important diagnosis.

04

Stimulants, medicines and heightened awareness

Caffeine, nicotine, alcohol, recreational stimulants and sympathomimetic medicines may provoke tachycardia or ectopy. Anxiety and hypervigilance can amplify awareness of otherwise normal beats without excluding a concurrent arrhythmia.

Pathophysiology

  1. 1
    Re-entry produces abrupt racing

    An electrical impulse repeatedly travels around a functional or anatomical circuit, activating the atria or atrioventricular junction rapidly. The resulting palpitation is often regular with sudden onset and termination.

  2. 2
    Disordered atrial activation creates irregularity

    In atrial fibrillation, chaotic atrial electrical activity reaches the atrioventricular node variably. Irregular ventricular filling and beat-to-beat stroke-volume changes create an uneven, sometimes forceful sensation.

  3. 3
    Premature depolarisation produces a pause and thump

    An ectopic focus fires before the expected sinus impulse, often generating a weak premature contraction followed by a pause of variable length. Extra filling can then make the following beat feel unusually forceful.

  4. 4
    Sinus acceleration increases heartbeat awareness

    Catecholamine release accelerates sinoatrial-node firing and increases contractility during demand or stress. Faster beats, more forceful contraction and focused attention can make a normal physiological response feel alarming.

Clinical features and red flags

Current instabilityRed flag

Look for hypotension or shock, syncope, pulmonary oedema, myocardial ischaemia, severe breathlessness or altered consciousness while the rhythm is present.

Sudden regular racing

Abrupt onset and offset with a very regular fast pulse favours a re-entrant supraventricular tachycardia, although a tracing is required.

Irregularly irregular sensation

An irregular pulse may reflect atrial fibrillation, frequent ectopy or another atrial rhythm; confirm on a 12-lead ECG.

Skipped beat with a thump

A premature beat followed by a pause and a forceful post-ectopic beat is common with atrial or ventricular ectopy.

High-risk historyRed flag

Exertional events, unexplained syncope, congenital heart disease, cardiomyopathy, previous myocardial infarction, or sudden death or inherited cardiomyopathy in a close relative are red flags.

Non-cardiac drivers

Fever, pain, anxiety, dehydration, anaemia, thyrotoxicosis, pregnancy, hypoglycaemia and stimulant exposure can produce sinus tachycardia or amplify normal beats.

Investigations

  1. 01
    12-lead ECGFirst step
    Why
    Document rhythm and screen for conduction disease, pre-excitation, long QT, Brugada pattern, ischaemia or hypertrophy.
    Interpretation and limitations
    An ECG during symptoms has the highest diagnostic value; an abnormal baseline ECG lowers the threshold for specialist review.
  2. 02
    FBC, U&Es, calcium, magnesium and thyroid function
    Why
    Identify anaemia, electrolyte disturbance and thyroid disease that can provoke palpitations.
    Interpretation and limitations
    Correct a clinically relevant abnormality and reassess, but do not attribute syncope or a dangerous tracing to a minor laboratory change without evidence.
  3. 03
    24-48 hour Holter monitor
    Why
    Capture frequent or daily symptoms and quantify ectopic burden.
    Interpretation and limitations
    Useful when symptoms occur at least every 24 hours; correlate time-stamped symptoms with the rhythm and quantify PVC percentage.
  4. 04
    Longer patch or patient-activated event recorder
    Why
    Capture episodes occurring more than 24 hours apart.
    Interpretation and limitations
    A longer recording window is preferred to serial short Holters; patient activation is helpful when consciousness is preserved.
  5. 05

Differential diagnosis

01

Atrial fibrillation

An irregularly irregular pulse and variable episode duration favour atrial fibrillation. A symptom-time ECG or suitable ambulatory recording is needed because examination between paroxysms may be normal.

02

Re-entrant supraventricular tachycardia

Very sudden onset and offset of a rapid, regular heartbeat favours a re-entrant supraventricular tachycardia. A 12-lead ECG during symptoms, including QRS width and atrial activity, helps separate it from sinus tachycardia and ventricular tachycardia.

03

Premature ectopic beats

A skipped beat, brief pause and subsequent thump suggest atrial or ventricular ectopy rather than sustained tachycardia. Ambulatory ECG correlates symptoms and measures burden, while echocardiography assesses suspected structural disease.

04

Systemic sinus tachycardia

Gradual acceleration with fever, exertion, dehydration, pallor, tremor or weight change suggests a sinus response. ECG morphology and targeted blood tests help identify the provoking illness.

05

Panic or anxiety symptoms

Fear, hyperventilation, tingling and a gradual adrenergic surge may accompany panic, but these features overlap with arrhythmia. A normal rhythm recorded during typical symptoms is more discriminating than assumption.

Management

01acutePalpitations happening nowFirst stepThe patient is symptomatic during assessment.+
  1. 1Perform ABCDE assessment, record observations and attach continuous ECG monitoring.
  2. 2Obtain a 12-lead ECG without delaying resuscitation; give oxygen only if hypoxaemic and obtain IV access if instability is possible.
  3. 3If shock, syncope, myocardial ischaemia, severe heart failure or a dangerous rhythm is present, activate emergency care and treat the documented rhythm using the current Resuscitation Council UK pathway.
  4. 4If stable, preserve the diagnostic ECG, check reversible causes and arrange disposition according to the rhythm and risk features.
02captureChoose monitoring by frequencyThe resting ECG is non-diagnostic and symptoms have resolved.+
  1. 1For symptoms at least daily, arrange a 24-48 hour Holter and a symptom/activity diary.

Complications

01

Syncope and injury

Very rapid tachycardia or profound bradycardia can transiently reduce cardiac output, causing syncope and traumatic falls. Palpitations immediately preceding loss of consciousness therefore increase urgency.

02

Tachycardia-mediated ventricular dysfunction

Persistent rapid rhythm or a substantial ectopic burden can impair ventricular function over time. Breathlessness, oedema or reduced exercise tolerance should prompt assessment for a potentially reversible cardiomyopathy.

03

Atrial thromboembolism

Atrial fibrillation reduces coordinated atrial emptying and promotes blood stasis, allowing thrombus formation and embolic stroke. Risk assessment depends on the confirmed rhythm and the person's clinical factors.

04

Ventricular arrhythmia and sudden death

Sustained ventricular tachycardia may deteriorate into ventricular fibrillation, particularly with infarct scar, cardiomyopathy or inherited electrical disease. Exertional episodes, syncope and relevant family history are warning clues.

Monitoring and follow-up

  • Record episode frequency, duration, onset and offset, trigger, pulse regularity and associated symptoms.
  • Keep a symptom and activity diary aligned to ambulatory-monitor timestamps.
  • Review monitor tracings for symptom-rhythm correlation, maximum and minimum rate, pauses, AF burden and ventricular ectopic burden.
  • Repeat U&Es, magnesium or thyroid tests after correcting a material abnormality or changing a causative medicine.
  • Escalate new syncope, exertional episodes, progressive breathlessness, chest pain or a family-history concern rather than simply extending monitoring.

Special situations

Frequency determines technology

A daily symptom is suited to Holter monitoring; a monthly symptom is not. The best device is the least invasive one with a realistic chance of recording an event.

A normal pulse after the event proves little

Paroxysmal arrhythmias can terminate before examination, so history and appropriate-duration monitoring remain important.

Consumer recordings can help

A clear single-lead tracing obtained during symptoms can guide assessment, but artefact and automated labels require clinical review and a diagnostic 12-lead ECG where possible.

Sinus tachycardia is usually a signal

When the rhythm is sinus, look for the physiological or pathological driver; suppressing the rate can obscure deterioration.

Burden matters for PVCs

NICE CKS advises echocardiography or cardiology assessment when ventricular ectopy exceeds 10% on ambulatory ECG because frequent PVCs can be associated with LV dysfunction.

Common pitfalls

  1. 01

    Calling all palpitations anxiety before a rhythm has been assessed.

  2. 02

    Ordering repeated 24-hour Holters for symptoms that occur only every few weeks.

  3. 03

    Relying on a smartwatch diagnosis without inspecting the tracing or obtaining a clinical ECG.

  4. 04

    Reassuring after a normal resting ECG despite exertional syncope or a family history of early sudden death.

  5. 05

    Treating sinus tachycardia with an antiarrhythmic instead of finding the cause.

Practice

Two practice questions

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Question 1 of 2
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CardiologyOriginal SBA

Selecting an ambulatory monitor

A 34-year-old has abrupt regular palpitations approximately once every 2 weeks. Examination and a resting 12-lead ECG are normal. There is no syncope or family history of sudden death. Which investigation is most likely to capture the rhythm?

Choose one answer, then submit
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Sources and review status6 sources · checked 27 Aug 2026 · clinical review pending+
Sources

Sources and review status

National guidance is shown before implementation-dependent detail. Apply principles in context and verify current guidance when a decision affects care. Source check completed 27 Aug 2026; clinical approval remains outstanding.

  • NICE CKS: PalpitationsAssessment, red flags, ECG and referral framework.
  • NICE CKS: History of palpitationsMonitoring selection and ventricular ectopy referral threshold.
  • NICE CKS: Current palpitationsEmergency admission features.
  • NICE NG196: Atrial fibrillation – recommendationsAmbulatory ECG duration for suspected paroxysmal AF.
  • NICE HTG606: KardiaMobile for detecting AFOption for selected people with suspected paroxysmal AF.
  • NHS: Heart palpitationsCurrent public red flags and trigger advice.

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

Authoring stateComplete draftClinical stateAwaiting reviewJurisdictionUnited Kingdom
Implantable loop recorder
Why
Investigate rare, recurrent unexplained syncope or infrequent concerning palpitations after non-invasive monitoring is unrevealing.
Interpretation and limitations
Automatic and patient-triggered recordings can establish whether bradycardia or tachycardia coincides with the event.
  • 06
    Echocardiogram or exercise testing
    Why
    Assess suspected structural disease or reproduce exertional symptoms under observation.
    Interpretation and limitations
    LV dysfunction, significant valve disease or exercise-induced arrhythmia changes risk and referral urgency.
    • 2
    For episodes more than 24 hours apart, choose a longer continuous patch, external event recorder or other ambulatory ECG for a period likely to include an event.
  • 3For rare recurrent syncope or high-risk episodes not captured non-invasively, seek specialist assessment for an implantable loop recorder.
  • 4Review the actual tracings and symptom markers; do not accept an automated device label without clinician confirmation.
    • 03low-riskLikely benign palpitationsNo red flags, normal examination and ECG, and isolated ectopy or sinus rhythm correlates with symptoms.+
    1. 1Explain the recorded rhythm and its prognosis rather than offering a vague reassurance.
    2. 2Reduce relevant triggers such as excess caffeine, alcohol, nicotine, recreational stimulants, dehydration and sleep loss.
    3. 3Treat an identified cause such as anaemia or thyroid disease and review medicines that can provoke tachycardia.
    4. 4Reassess if symptoms change, become exertional, cause presyncope or syncope, or are accompanied by chest pain or breathlessness.