Atrial Fibrillation — Fast Ventricular Rate

In AF with rapid ventricular rate, first assess haemodynamic stability. Unstable (SBP <90, chest pain, syncope, acute pulmonary oedema) → DC cardioversion. Stable → rate control first. Always look for a precipitant.

AF Rate/Rhythm Control

The pathway

1 · Assess haemodynamic status

SBP <90, chest pain, syncope, or acute pulmonary oedema → UNSTABLE
Immediate DC cardioversion (synchronised 120–200J biphasic). Call anaesthetics.

2 · Stable: Rate control

Bisoprolol 2.5–5mg PO or metoprolol 2.5mg IV slow bolus
Or diltiazem if beta-blockers contraindicated
Target HR <110 at rest.

3 · Find the cause

Infection/sepsis
Electrolyte abnormalities (K+, Mg)
Thyrotoxicosis
PE
MI
Alcohol

Treat the underlying cause.

4 · Anticoagulation decision

CHA₂DS₂-VASc ≥2 (men) or ≥3 (women): start anticoagulation
If AF >48h: anticoagulate ≥3 weeks before rhythm control, or TOE to exclude thrombus.

5 · Rhythm control

If AF onset <48h and haemodynamically stable: consider pharmacological cardioversion (flecainide 300mg PO if no structural heart disease, or amiodarone IV).

6 · Electrolytes

Correct K+ (target >4 mmol/L)
Mg (1–2g IV MgSO₄ if low).

Drugs

Drug	Dose	Route	Notes
Bisoprolol	2.5–5mg	PO	Rate control. Avoid in asthma, decompensated HF.
Metoprolol	2.5mg	IV	Slow bolus. Can repeat. Rate control in acute setting.
Digoxin	500mcg	IV	Rate control if beta-blockers contraindicated (e.g. severe HF). Slow onset.
Amiodarone	300mg over 1h then 900mg over 23h	IV	Rhythm control. Use in structural heart disease.
Flecainide	300mg	PO	Rhythm control. ONLY if no structural heart disease or coronary disease.
Apixaban	5mg BD	PO	Anticoagulation. Reduce to 2.5mg BD if 2/3 criteria: age≥80, weight≤60kg, Cr≥133.

When to escalate

Haemodynamic instability → immediate DC cardioversion,Suspected WPW (irregular broad complex) → do not use AV nodal blockers,Refractory rate despite dual rate control agents,New onset in ACS or post-cardiac surgery

Reference: ESC AF Guidelines 2023 / NICE NG196

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