Related Subjects:
|AF - General
|AF and Anticoagulation
|AF and Rate Control
|AF and Rhythm Control and Cardioversion
|AF ECG
|DC cardioversion
⚡ Introduction
- Fast atrial fibrillation (AF) causes inefficient cardiac output and may worsen heart failure, angina, or exercise intolerance.
- Ventricular rates > 160/min are often poorly tolerated but depends on various factors.
- Many older tolerate rates up to ~160/min unless severe LV dysfunction or valvular disease is present. Slowly lower it.
- Drugs take time to act so set goals e.g. < 120/min in 1-2 hour if BP ok
- Management differs between acutely unwell patients and long-term outpatient care.
🚑 Acute AF Rate Control
- Always search for triggers: infection, dehydration, metabolic disturbance, PE, alcohol, or worsening pulmonary oedema.
- Correct K⁺/Mg²⁺, treat precipitants, oxygen only if hypoxic. Consider treating sepsis, dehydration, ACS, PE, thyrotoxicosis
- Haemodynamic compromise (shock, angina, pulmonary oedema, hypotension):
- ➡️ Immediate DC cardioversion 120–200 J biphasic → 200 J (can be done without prior anticoagulation if emergency, but give treatment-dose LMWH) [NICE, 2014].
- Drug therapy:
- Beta-blocker: Consider Bisoprolol 2.5 mg PO stat if comfortable and stable and BP > 100 mmHg. If BP less than 100 mmHg give Metoprolol 1 mg IV (repeat to max 10 mg) to reduce HR to 100-120/min. Avoid in asthma, acute pulmonary oedema, severe bradycardia.
- Amiodarone: 150–300 mg slow IV over 30 min (large vein/central line), alternative if beta blockers not available or contraindicated then 900 mg/24h infusion. Ensure vein is flushed.
- Digoxin: 500 mcg PO, repeat 500 mcg after 8h, then 125 mcg OD. Best for patients with CCF or sedentary lifestyle. Dose adjust in elderly or renal impairment.
- Special case: Suspected pre-excited AF (very fast, irregular, broad complexes) → avoid AV-nodal blockers; seek senior help/consider urgent cardioversion or consider Procainamide 10–15 mg/kg IV over 30–60 min.
- Anticoagulation: Start LMWH or a DOAC unless contraindicated.
📆 Long-Term Rate Control
- Bisoprolol: 2.5–5 mg PO OD. First-line. Avoid in asthma or decompensated heart failure.
- Verapamil: 40–120 mg PO TDS. Alternative if beta-blockers not tolerated. ❌ Never combine with beta-blockers (risk of complete heart block).
- Digoxin: Load (500 mcg stat, then 250 mcg 6–8h later), then maintain 125 mcg OD.
- Good in elderly or sedentary patients with CCF.
- Lower dose if low body mass or renal impairment.
- Amiodarone: Only if no alternatives (significant long-term toxicity).
- Loading: 200 mg TDS for 1 week → 200 mg BD for 1 week → 200 mg OD maintenance.
- Counsel re: thyroid, liver, and pulmonary side effects.
🔑 Clinical Pearls
- Always consider anticoagulation (CHA₂DS₂-VASc and HAS-BLED assessment).
- Acute rate control is not just about drugs — treat the underlying precipitant.
- Long-term: aim for resting HR < 110/min (lenient control, RACE II trial) unless symptomatic.
- Digoxin alone is not adequate for active patients as it only slows resting HR.
- Amiodarone is for rhythm control rescue, not first-line long-term rate control.
