Overview
Atrial Fibrillation with Rapid Ventricular Response
Topic Overview
Summary
Atrial fibrillation with rapid ventricular response (AF-RVR) presents with uncontrolled heart rate (typically over 100 bpm, often over 150 bpm) causing symptoms or haemodynamic instability. Management depends on stability: unstable patients require DC cardioversion; stable patients need rate control (beta-blockers, calcium channel blockers, or digoxin). Anticoagulation is critical for stroke prevention. Always search for reversible causes (sepsis, PE, thyrotoxicosis).
Key Facts
- Definition: AF with ventricular rate over 100 bpm (typically over 110-150)
- Unstable signs: Hypotension, chest pain, heart failure, decreased consciousness — requires DC cardioversion
- Stable: Rate control first-line (beta-blocker or diltiazem)
- Avoid AV nodal blockers in WPW/pre-excited AF — can precipitate VF
- Anticoagulation: CHA₂DS₂-VASc score guides long-term stroke prevention
- Reversible causes: Sepsis, PE, thyrotoxicosis, alcohol, electrolyte disturbance
Clinical Pearls
Always look for a CAUSE — AF with RVR is often a symptom of something else (sepsis, PE, thyrotoxicosis)
Pre-excited AF (WPW) with broad QRS — do NOT give AV nodal blockers; use DC cardioversion or procainamide
Rate control before rhythm control in most acute presentations
Why This Matters Clinically
AF is the most common sustained arrhythmia. Rapid rates cause symptoms, can precipitate heart failure, and if untreated lead to tachycardia-induced cardiomyopathy. Recognising instability, choosing the right rate control agent, and initiating anticoagulation appropriately are essential skills.
Visual Summary
Visual assets to be added:
- AF ECG with rapid ventricular response
- Acute AF management algorithm
- CHA₂DS₂-VASc score calculator infographic
- DC cardioversion setup photograph
Epidemiology
Incidence
- UK prevalence: 1.5 million people with AF
- Prevalence increases with age: Under 1% at 40; over 10% at 80
- ED presentations: AF is one of the top 5 cardiac presentations
Demographics
- Age: Strong association with advancing age
- Sex: Slightly more common in men
- Comorbidities: Hypertension, heart failure, valvular disease, diabetes
Causes of New/Rapid AF
| Category | Examples |
|---|---|
| Cardiac | IHD, heart failure, valvular disease (especially mitral), hypertensive heart disease |
| Systemic | Sepsis, thyrotoxicosis, PE, hypoxia, electrolyte disturbance (K+, Mg2+) |
| Toxic | Alcohol ("holiday heart"), caffeine, sympathomimetics |
| Post-operative | Common after cardiac/thoracic surgery |
Pathophysiology
Mechanism of AF
- Multiple wavelet re-entry or focal triggers (often from pulmonary veins)
- Atrial rate 400-600/min
- AV node filters impulses → irregular ventricular response
Why Rate Becomes Rapid
- High sympathetic tone (sepsis, pain, anxiety, hypovolaemia)
- Hyperthyroidism
- Reduced AV nodal block (drugs, catecholamines)
- Accessory pathway (WPW) — bypasses AV node, can conduct at very high rates
Haemodynamic Consequences
- Loss of atrial kick (20-25% of cardiac output)
- Reduced diastolic filling time → reduced stroke volume
- Increased myocardial oxygen demand → ischaemia
- Tachycardia-induced cardiomyopathy (persistent fast AF)
Pre-Excited AF (WPW)
- Accessory pathway conducts rapidly (no AV node filtering)
- Ventricular rates can exceed 250 bpm
- AV nodal blockers promote conduction down accessory pathway → VF
- Treat with DC cardioversion or procainamide/flecainide
Clinical Presentation
Symptoms
Signs
Adverse Features (Unstable — Require DC Cardioversion)
| Feature | Significance |
|---|---|
| Shock | Hypotension, pallor, sweating, cold peripheries |
| Syncope/pre-syncope | Cerebral hypoperfusion |
| Myocardial ischaemia | Chest pain, ECG changes |
| Heart failure | Pulmonary oedema |
Palpitations (irregular, fast)
Common presentation.
Dyspnoea
Common presentation.
Chest discomfort
Common presentation.
Dizziness / presyncope
Common presentation.
Fatigue
Common presentation.
Exercise intolerance
Common presentation.
Clinical Examination
Cardiovascular
- Pulse: Irregularly irregular, rate over 100
- BP: May be low or high
- JVP: Elevated if heart failure
- Apex: Irregular
- Murmurs: Mitral stenosis/regurgitation
Look for Underlying Cause
- Goitre (thyrotoxicosis)
- Fever (sepsis)
- Signs of DVT/PE
- Alcohol history
ECG Features of AF
| Feature | Description |
|---|---|
| No P waves | Replaced by fibrillatory waves |
| Irregular R-R intervals | Hallmark |
| Narrow QRS | Unless bundle branch block or pre-excitation |
| Rapid rate | Over 100 (often 120-180) |
Pre-Excited AF (WPW) ECG
- Very fast, irregular rhythm
- Wide QRS (pre-excited, not BBB)
- Delta waves may be visible
- DANGER: AV nodal blockers contraindicated
Investigations
Immediate
| Investigation | Purpose |
|---|---|
| 12-lead ECG | Confirm AF, exclude pre-excitation, ischaemia |
| Observations | HR, BP, SpO₂ |
| Blood glucose | Hypoglycaemia |
Laboratory
| Test | Purpose |
|---|---|
| U&E | K+, Mg2+ (arrhythmia precipitants) |
| TFTs | Thyrotoxicosis |
| FBC, CRP | Sepsis |
| Troponin | Demand ischaemia or ACS as precipitant |
| D-dimer/CTPA | If PE suspected |
| LFTs | Liver congestion, alcohol |
Imaging
- CXR: Heart failure, infection
- Echocardiography: LV function, valvular disease, LA size
Classification & Staging
AF Classification (Duration)
| Type | Duration |
|---|---|
| Paroxysmal | Terminates spontaneously within 7 days |
| Persistent | Over 7 days; requires intervention to terminate |
| Long-standing persistent | Over 12 months; rhythm control still considered |
| Permanent | Decision not to pursue rhythm control |
CHA₂DS₂-VASc Score (Stroke Risk)
| Factor | Points |
|---|---|
| CHF/LV dysfunction | 1 |
| Hypertension | 1 |
| Age ≥75 | 2 |
| Diabetes | 1 |
| Stroke/TIA/TE | 2 |
| Vascular disease | 1 |
| Age 65-74 | 1 |
| Sex category (female) | 1 |
Anticoagulation thresholds (NICE):
- Men: CHA₂DS₂-VASc ≥1 → consider DOAC
- Women: CHA₂DS₂-VASc ≥2 → consider DOAC
Management
UNSTABLE AF (Adverse Features Present)
- Synchronised DC Cardioversion
- Sedation/anaesthesia required
- Start at 120-150J biphasic
- Up to 3 shocks
- If unsuccessful → amiodarone 300mg IV over 20-60 min then infusion
STABLE AF — Rate Control First-Line
| Drug | Dose | Notes |
|---|---|---|
| Beta-blocker (bisoprolol, metoprolol) | Bisoprolol 2.5-5mg PO; Metoprolol 25-50mg PO | First-line unless contraindicated |
| Diltiazem | 60-120mg PO (or 15-25mg IV) | Alternative if beta-blocker contraindicated |
| Digoxin | 500mcg IV/PO then 250mcg in 6h | For sedentary patients or heart failure |
| Amiodarone | 300mg IV over 1h then infusion | If other agents contraindicated |
Avoid in WPW/Pre-Excited AF:
- Beta-blockers, calcium channel blockers, digoxin, adenosine
- Use DC cardioversion, procainamide, or flecainide instead
Rate vs Rhythm Control
| Approach | Indications |
|---|---|
| Rate control | Default for most; symptomatic control |
| Rhythm control | New-onset (under 48h), reversible cause, young/symptomatic, HFrEF |
Anticoagulation
Acute setting:
- If AF under 48 hours: Cardioversion can proceed without prior anticoagulation (then 4 weeks DOAC)
- If AF over 48 hours or uncertain: 3 weeks anticoagulation OR TOE to exclude thrombus before cardioversion
Long-term:
- CHA₂DS₂-VASc score guides DOAC use
- DOACs preferred over warfarin: Apixaban, rivaroxaban, edoxaban, dabigatran
Treat Underlying Cause
- Sepsis: Antibiotics, fluids
- PE: Anticoagulation
- Thyrotoxicosis: Beta-blocker, refer endocrinology
- Electrolyte correction (K+, Mg2+)
- Alcohol cessation
Complications
Acute
- Haemodynamic instability / cardiogenic shock
- Acute heart failure / pulmonary oedema
- Myocardial ischaemia
Long-Term
- Stroke / systemic embolism — major concern; hence anticoagulation
- Tachycardia-induced cardiomyopathy (reversible with rate control)
- Bleeding on anticoagulation
- Heart failure progression
Prognosis & Outcomes
Mortality
- AF increases mortality 1.5-2× compared to sinus rhythm
- Mortality largely driven by stroke and heart failure
Outcomes with Treatment
- Rate control improves symptoms and prevents cardiomyopathy
- Anticoagulation reduces stroke by 65%
- Rhythm control may improve outcomes in early AF/heart failure (EAST-AFNET 4)
Evidence & Guidelines
Key Guidelines
- NICE NG196: Atrial Fibrillation (2021)
- ESC Guidelines for AF Management (2020)
- Resuscitation Council UK: Tachycardia Algorithm
Key Trials
- AFFIRM, RACE: Rate vs rhythm control — no mortality difference (older trials)
- EAST-AFNET 4: Early rhythm control associated with better outcomes
- RE-LY, ROCKET-AF, ARISTOTLE, ENGAGE-AF: DOAC vs warfarin trials
Patient & Family Information
What is Atrial Fibrillation?
Atrial fibrillation (AF) is an irregular and often fast heartbeat. The upper chambers of the heart (atria) beat chaotically instead of regularly.
Symptoms
- Palpitations (feeling your heart racing or fluttering)
- Shortness of breath
- Dizziness
- Tiredness
Why Treatment Matters
- Slowing the heart rate reduces symptoms
- Blood-thinning medication prevents strokes
- Finding and treating the cause is important
What Happens Next
- Medication to control heart rate
- Blood-thinning medication if needed
- Investigation for underlying causes
- Follow-up with cardiology if required
Resources
References
Primary Guidelines
- NICE. Atrial Fibrillation: Diagnosis and Management (NG196). 2021. nice.org.uk
- Hindricks G, et al. 2020 ESC Guidelines for the diagnosis and management of atrial fibrillation. Eur Heart J. 2021;42(5):373-498. PMID: 32860505
Key Trials
- Kirchhof P, et al. Early Rhythm-Control Therapy in Patients with Atrial Fibrillation (EAST-AFNET 4). N Engl J Med. 2020;383(14):1305-1316. PMID: 32865375
- Granger CB, et al. Apixaban versus warfarin in patients with atrial fibrillation (ARISTOTLE). N Engl J Med. 2011;365(11):981-992. PMID: 21870978