Three questions determine the management: is the patient unstable, how long has the fibrillation lasted, and does the patient need an anticoagulant?
The unstable patient
Immediate electrical cardioversion, without delay, in any of the following:
- A systolic blood pressure < 90 mmHg caused by the arrhythmia.
- Ongoing myocardial ischaemia with chest pain and ECG changes.
- Acute pulmonary oedema.
- Impaired consciousness.
Synchronised cardioversion under sedation, at an energy level according to the local protocol. An anticoagulant is given as soon as possible, but must not delay cardioversion in an unstable patient.
Rate control in the stable patient
| Drug | Situation | Comment |
|---|---|---|
| Beta blocker (metoprolol) | First choice in most cases | The IV dose is titrated slowly. Caution in acute heart failure and in obstructive airways disease |
| Verapamil or diltiazem | When a beta blocker is contraindicated, for example in asthma | Contraindicated in impaired left ventricular function and together with an intravenous beta blocker |
| Digoxin | In heart failure or hypotension, or as an add-on | Slow onset. Dose reduction in renal failure and in old age |
| Amiodarone | In severe haemodynamic compromise where the above cannot be used | It also has a rhythm-control effect; plan as though cardioversion will occur |
Target rate in the acute phase: a resting ventricular rate < 110/min is a sufficient initial target in most patients. Doses according to the local protocol and the Swedish medicines compendium (FASS).
Rhythm control: the time limit before cardioversion
| Duration | Management |
|---|---|
| Reliably < 24 hours, no mechanical valve, CHA₂DS₂-VA 0–1 | Cardioversion (electrical or pharmacological) can be performed directly. An anticoagulant is then given according to CHA₂DS₂-VA |
| 24–48 hours, or risk factors present | An anticoagulant before cardioversion, or alternatively transoesophageal echocardiography. Cardioversion without preceding anticoagulation is reserved for CHA₂DS₂-VA 0–1 |
| > 48 hours or unknown duration | An anticoagulant for at least 3 weeks before cardioversion, or alternatively transoesophageal echocardiography to exclude thrombus |
| After cardioversion, irrespective of duration | An anticoagulant for at least 4 weeks, thereafter according to CHA₂DS₂-VA |
The limit is 24 hours, not 48. The 2024 ESC guidelines and several Swedish clinical knowledge resources have tightened the former 48-hour rule for patients with risk factors. Check what applies in your own region.
The time limit is not a guarantee. Where the stroke risk is high or the time of onset uncertain, choose the more cautious course.
Anticoagulation
Assess the risk with CHA₂DS₂-VA (the sex category has been removed from the Swedish recommendation).
| Score | Recommendation |
|---|---|
| 0 | No anticoagulant |
| 1 | Consider an oral anticoagulant, particularly at age ≥ 65 years |
| ≥ 2 | An oral anticoagulant is recommended |
A DOAC is preferred to warfarin except in a mechanical valve prosthesis and in moderate to severe mitral stenosis, where warfarin applies. Apixaban is often preferred, among other reasons because it has the least renally dependent elimination.
| Agent | Standard dose in atrial fibrillation | Criteria for dose reduction according to FASS |
|---|---|---|
| Apixaban | 5 mg × 2 | 2.5 mg × 2 if at least two of: age ≥ 80 years, weight ≤ 60 kg, creatinine ≥ 133 µmol/L |
| Rivaroxaban | 20 mg × 1 | 15 mg × 1 at an eGFR of 15–49 mL/min |
| Edoxaban | 60 mg × 1 | 30 mg × 1 at an eGFR of 15–50 mL/min, weight ≤ 60 kg, or concomitant P-gp inhibitor |
| Dabigatran | 150 mg × 2 | 110 mg × 2 at age ≥ 80 years, with concomitant verapamil, or with an increased bleeding risk |
Renal thresholds: a DOAC is given at an eGFR > 30 mL/min. At an eGFR of 15–30 mL/min the documentation is inadequate and closer monitoring is required. Dabigatran is contraindicated at an eGFR < 30 mL/min. Check the full blood count and creatinine when treatment is started, at follow-up after one month, and at least annually thereafter, more often in impaired renal function.
Red flags and pitfalls
- Atrial fibrillation with pre-excitation (WPW). A broad, irregular, rapid tachycardia. Do not give a beta blocker, verapamil, diltiazem, digoxin or adenosine. Cardiovert.
- Fibrillation is a symptom, not a diagnosis. Look for a precipitating cause: sepsis, pulmonary embolism, hyperthyroidism, anaemia, alcohol, acute coronary syndrome, heart failure. Rate control without treating the cause will fail.
- Stopping the anticoagulant after successful cardioversion. It is not the rhythm that determines the stroke risk but the risk profile.
- Aspirin has no place as stroke prophylaxis in atrial fibrillation.
- Verapamil plus an intravenous beta blocker can cause asystole.
Sources
- ESC Guidelines for the management of atrial fibrillation.
- ACC/AHA/ACCP/HRS Guideline for the Diagnosis and Management of Atrial Fibrillation.
- The summary of product characteristics for each direct oral anticoagulant.
