AKT · Cardiovascular/Arrhythmias & conduction

Atrial fibrillation & flutter

Disorganised atrial electrical activity → irregular ventricular response (AF) / macro-reentrant atrial circuit (flutter)

Overview

The commonest sustained arrhythmia. AF = chaotic atrial activity with an irregularly irregular pulse and no P waves; flutter = a re-entrant circuit giving sawtooth flutter waves, often 2:1 (ventricular ~150). Management has three arms: rate vs rhythm control, and — crucially — stroke prevention guided by CHA₂DS₂-VASc, with a DOAC first-line.

Recognise

Irregularly irregular pulse; palpitations, breathlessness, fatigue, chest discomfort; may be asymptomatic
ECG: absent P waves with irregular QRS (AF); sawtooth flutter waves with regular ventricular rate (flutter)
Causes — the mnemonic SMITH: Sepsis, Mitral valve disease, Ischaemia/IHD, Thyrotoxicosis, Hypertension; also alcohol, PE

Red flags

Haemodynamic instability (shock, syncope, ischaemia, heart failure) → emergency synchronised DC cardioversion
AF with a very broad/irregular fast tachycardia → consider WPW; AVOID AV-node blockers (digoxin/verapamil) which can accelerate the accessory pathway

Differentials & how to tell them apart

Atrial flutterregular sawtooth waves, often 2:1 at ~150 — managed similarly, ablation more curative

Multifocal atrial tachycardia≥3 P-wave morphologies, often in COPD

Ventricular ectopics / sinus arrhythmiaP waves present; pattern differs

Atrial fibrillation — irregularly irregular rhythm with absent P waves (ECG)
Ewingdo / CC BY-SA 4.0 — Wikimedia Commons

Investigations

12-lead ECG (irregular, no P waves / flutter waves); ambulatory monitor for paroxysmal AF. FBC, U&Es, TFTs (exclude thyrotoxicosis), echo (structural/valve disease). CHA₂DS₂-VASc for stroke risk; ORBIT for bleeding risk.

Management

Rate control (beta-blocker or rate-limiting CCB) + anticoagulation by CHA₂DS₂-VASc (DOAC first-line)

1Assess stability. Stratify stroke risk with CHA₂DS₂-VASc and start a DOAC if indicated; assess bleeding with ORBIT. Control rate with a beta-blocker or rate-limiting CCB.Gate: If haemodynamically unstable (shock, syncope, ischaemia, severe heart failure) → emergency synchronised DC cardioversion, don't titrate drugs.
2Consider rhythm control (flecainide/amiodarone or cardioversion) if symptomatic despite rate control, new-onset/reversible cause, or AF-driven heart failure.Gate: Elective cardioversion of AF >48 h needs ≥3 weeks of therapeutic anticoagulation first (or a TOE to exclude atrial thrombus) — otherwise risk of embolic stroke.
3Catheter ablation for drug-refractory paroxysmal/persistent AF or typical flutter; pace-and-ablate for refractory rate control.

Anticoagulation by CHA₂DS₂-VASc — DOAC first-line (apixaban/rivaroxaban/edoxaban/dabigatran) — offer if score ≥2; consider in men with score 1; warfarin if mechanical valve or moderate-severe mitral stenosis. Assess bleeding with ORBIT — do NOT withhold solely for falls risk

Rate control first-line: beta-blocker OR rate-limiting CCB (diltiazem/verapamil) — first-line for most; digoxin only if sedentary/heart failure; do not use verapamil + beta-blocker together

Rhythm control: flecainide or amiodarone; DC cardioversion — if 48 h (or TOE to exclude thrombus)

Catheter ablation — for paroxysmal/persistent AF refractory to or intolerant of drugs; very effective for typical flutter

Key points

Irregularly irregular pulse with no P waves = AF → CHA₂DS₂-VASc decides anticoagulation (DOAC first-line), then rate control (beta-blocker/rate-limiting CCB). Unstable → DC cardioversion. >48 h before elective cardioversion = 3 weeks' anticoagulation or TOE first. Falls risk alone is NOT a reason to withhold a DOAC.

Monitor & prognosis

Rate/symptom control, renal function for DOAC dosing, annual stroke/bleeding reassessment.

Good with anticoagulation; untreated AF carries a 5-fold stroke risk.

Source: NICE NG196 (atrial fibrillation)