Why AF Management Is Examined
Atrial fibrillation is the most common sustained cardiac arrhythmia, affecting over 1 million people in the UK. It is the most common cause of cardioembolic stroke. OSCEs examine it in ECG interpretation stations, prescribing stations (anticoagulate this patient), clinical reasoning (this patient's AF is uncontrolled — what do you do?), and communication stations (explaining anticoagulation to a patient). Examiners test CHA2DS2-VASc scoring, correct drug choice, and cardioversion indications.
ECG Features of AF
🧠 Mnemonic
AF on ECG — IIRR:
- I rregularly I rregular rhythm (no two R-R intervals the same)
- R eplacement of P waves with fibrillatory baseline (f waves — irregular, variable amplitude, 350-600/min)
- R apid ventricular rate (typically 100-160/min if untreated)
Key: if the rhythm is irregular and there are no discrete P waves before each QRS, it is AF until proven otherwise.
Classification
| Type | Definition |
|---|---|
| First detected | New diagnosis — may be first or recurrent |
| Paroxysmal | Self-terminating episodes, usually within 48 hours (up to 7 days) |
| Persistent | Episode lasting more than 7 days (requires cardioversion to terminate) |
| Long-standing persistent | Continuous AF for more than 12 months |
| Permanent | Patient and clinician accept AF as ongoing — no further cardioversion attempts |
Causes and Precipitants — PIRATES
🧠 Mnemonic
PIRATES — AF causes:
- P ericarditis / P ulmonary embolism
- I schaemia (acute MI, ischaemic cardiomyopathy)
- R heumatic heart disease (mitral stenosis — most AF-provoking valvular disease)
- A lcohol (holiday heart syndrome — AF after binge drinking)
- T hyrotoxicosis (TFTs in all new AF)
- E lectrolyte disturbance (hypokalaemia, hypomagnesaemia)
- S epsis / S urgery (post-operative AF common after cardiac and thoracic surgery)
Acute AF Management — Unstable vs Stable
Haemodynamically Unstable (Any of: SBP below 90, chest pain, syncope, heart failure, HR above 150 with compromise)
- Immediate synchronised DC cardioversion — do not delay for anticoagulation
- Sedation/anaesthetic review
- Treat underlying cause
Haemodynamically Stable
Step 1: Rate control or rhythm control decision
| Prefer rate control | Prefer rhythm control |
|---|---|
| Permanent AF | New-onset AF (under 48 hours or anticoagulated for 3 weeks) |
| Older patients (above 65) with few symptoms | Symptomatic despite rate control |
| Multiple comorbidities | Younger patients |
| AF for over 12 months | First presentation |
Rate Control
Target: resting HR below 110 bpm (RACE II — lenient rate control equally effective to strict control for most)
| Drug | Dose | Notes |
|---|---|---|
| Bisoprolol (beta-blocker) | 2.5-10 mg OD | First-line — avoid in asthma, COPD with significant bronchospasm, decompensated HF |
| Diltiazem (rate-limiting CCB) | 60-120 mg BD | Avoid in HFrEF (negative inotrope) |
| Digoxin | Loading dose 500 micrograms then 62.5-250 micrograms OD | Third-line — good for sedentary patients; poor rate control during exercise; narrow therapeutic index |
| Verapamil | 40-120 mg TDS | Avoid in HFrEF; never combine with beta-blocker |
| Amiodarone | For rate control in acute HF only | Consider only if other agents unsuitable or haemodynamically compromised |
Rhythm Control
Pharmacological cardioversion (pharmacological for AF under 48 hours):
- Flecainide 300 mg PO (or IV) — most effective; contraindicated in structural heart disease, IHD, LV impairment
- Amiodarone — for patients with structural heart disease
Electrical cardioversion (DC cardioversion):
- Synchronised biphasic shock (100-200 J)
- Requires anticoagulation: 3 weeks DOAC before cardioversion if AF for over 48 hours, OR TOE to exclude left atrial appendage thrombus
- Continue anticoagulation for minimum 4 weeks after cardioversion (stunning — risk of embolism even after successful cardioversion)
Long-term rhythm control:
- Flecainide (if no structural heart disease) or amiodarone
- Catheter ablation (pulmonary vein isolation) — increasingly first-line in young, symptomatic paroxysmal AF
Anticoagulation — CHA2DS2-VASc Score
| Risk factor | Points |
|---|---|
| Congestive heart failure | 1 |
| Hypertension | 1 |
| Age 75 or above | 2 |
| Diabetes mellitus | 1 |
| Stroke / TIA / thromboembolism (prior) | 2 |
| Vascular disease (prior MI, peripheral arterial disease, aortic plaque) | 1 |
| Age 65-74 | 1 |
| Sex category female | 1 |
| Score | Anticoagulation recommendation |
|---|---|
| Male 0 / Female 1 | Low risk — no anticoagulation |
| Male 1 / Female 2 | Consider anticoagulation (discuss risk/benefit) |
| Male 2 or above / Female 3 or above | Anticoagulate |
First-line: DOAC (apixaban, rivaroxaban, edoxaban, dabigatran)
- Superior to warfarin for stroke prevention, lower bleeding risk (especially intracranial haemorrhage)
- Exception: valvular AF (rheumatic mitral stenosis or mechanical heart valve) — warfarin mandatory (DOACs not validated)
Frequently Asked Questions
"When should you not anticoagulate a patient with AF?"
Anticoagulation carries bleeding risk. Before starting, assess bleeding risk using HAS-BLED score. Temporary absolute contraindications include: active major bleeding, recent intracranial haemorrhage, planned high-bleed-risk surgery within 48 hours. Relative contraindications (weigh against stroke risk): thrombocytopaenia below 50, uncontrolled hypertension, history of falls, alcohol excess, poor medication compliance. High CHA2DS2-VASc usually outweighs bleeding risk — anticoagulation reduces net clinical events in most patients.
"What is the difference between paroxysmal and persistent AF?"
Paroxysmal AF self-terminates (usually within 48 hours, by definition within 7 days). Persistent AF lasts more than 7 days and requires intervention (cardioversion — electrical or pharmacological) to restore sinus rhythm. Long-standing persistent AF is continuous for more than 12 months. Permanent AF is accepted as the ongoing rhythm. These distinctions matter clinically because they inform cardioversion candidacy, anticoagulation planning, and prognosis — paroxysmal AF carries the same stroke risk as persistent AF.
"What is holiday heart syndrome?"
Holiday heart syndrome refers to AF (and other arrhythmias) triggered by acute alcohol intoxication, typically after binge drinking. It was first described in young, otherwise healthy people without structural heart disease presenting with AF after heavy alcohol consumption at weekends or holidays. The mechanism involves direct toxic effects on myocardial electrophysiology, sympathetic activation, electrolyte disturbance, and vagal effects. Most episodes self-terminate within 24 hours with abstinence and supportive care.
"How do you manage a patient on warfarin for AF who needs urgent surgery?"
If truly urgent: reverse anticoagulation with IV vitamin K 5-10 mg and 4-factor prothrombin complex concentrate (PCC) — target INR below 1.5. For semi-elective surgery: stop warfarin 5 days before; bridge with LMWH if very high thromboembolic risk (mechanical mitral valve, recent stroke). For most AF patients (non-valvular, no recent stroke): bridging with LMWH is not recommended (BRIDGE trial) — risk of bridging haemorrhage exceeds thrombotic benefit.
"What is catheter ablation for AF and who is it suitable for?"
Catheter ablation (pulmonary vein isolation) electrically disconnects the pulmonary veins — where most AF triggers originate — from the left atrium using radiofrequency energy or cryotherapy. It is increasingly recommended as first-line rhythm control for young, symptomatic paroxysmal or persistent AF, and for patients who have failed antiarrhythmic drugs. It achieves freedom from AF in approximately 60-70% at 1 year (paroxysmal). EAST-AFNET 4 trial showed early rhythm control (including ablation) reduces cardiovascular events compared to rate control alone.
Related Posts
- ECG Interpretation OSCE — identifying AF and other arrhythmias on the 12-lead ECG
- Stroke and TIA Assessment OSCE — AF as the leading cardioembolic cause of stroke
- Palpitations History OSCE — taking a systematic history in the patient presenting with AF