Initial Evaluation and Management of Atrial Fibrillation
Immediate Assessment and Stabilization
Perform immediate synchronized electrical cardioversion (≥200 J biphasic) without awaiting anticoagulation in any patient with hemodynamic instability—defined as symptomatic hypotension (systolic BP <90 mmHg), acute pulmonary edema, ongoing chest pain, altered mental status, or cardiogenic shock. 1, 2 Give an intravenous heparin bolus concurrently if feasible. 1
For hemodynamically stable patients, confirm the diagnosis with a 12-lead ECG documenting irregularly irregular rhythm with absent P waves. 1, 2
Diagnostic Work-Up
Obtain the following tests immediately:
- Transthoracic echocardiogram to assess left atrial size, left ventricular ejection fraction (LVEF), valvular disease, and structural abnormalities 1, 2
- Thyroid-stimulating hormone, complete blood count, serum creatinine, electrolytes, and liver function tests to identify reversible causes 3, 2
- Calculate CHA₂DS₂-VASc score using: congestive heart failure (1 point), hypertension (1 point), age ≥75 years (2 points), diabetes (1 point), prior stroke/TIA/thromboembolism (2 points), vascular disease (1 point), age 65-74 years (1 point), female sex (1 point) 1, 2
Screen for precipitating factors: hyperthyroidism, acute alcohol intoxication, pulmonary embolism, myocardial infarction, pericarditis, myocarditis, hypertensive crisis, and obstructive sleep apnea. 3, 1
Anticoagulation Strategy
Initiate oral anticoagulation immediately for all patients with CHA₂DS₂-VASc score ≥2 (men) or ≥3 (women). 1, 2 Consider anticoagulation for score of 1 (men) or 2 (women) after individualized bleeding-risk assessment. 1
First-Line Anticoagulant Choice
Prescribe a direct oral anticoagulant (DOAC)—apixaban, rivaroxaban, edoxaban, or dabigatran—as first-line therapy over warfarin in all patients except those with mechanical heart valves or moderate-to-severe mitral stenosis. 1, 2 DOACs provide lower intracranial hemorrhage risk and more predictable pharmacokinetics. 1
- Apixaban: 5 mg twice daily (or 2.5 mg twice daily if ≥2 of: age ≥80 years, weight ≤60 kg, creatinine ≥1.5 mg/dL) 1, 2
Warfarin Management (When Required)
Target INR 2.0–3.0; monitor weekly during initiation and monthly once stable. 3, 1
Critical Anticoagulation Principle
Continue anticoagulation indefinitely based on CHA₂DS₂-VASc score regardless of whether sinus rhythm is restored—stroke risk is determined by underlying risk factors, not rhythm status. 1, 2 In the AFFIRM trial, 72% of strokes occurred after anticoagulation was stopped or when INR was subtherapeutic. 1
Rate Control Strategy
Rate control combined with anticoagulation is the recommended initial approach for most patients; it provides mortality and cardiovascular outcomes equivalent to rhythm control while producing fewer adverse effects and hospitalizations. 1, 4
Rate-Control Algorithm Based on LVEF
LVEF >40% (Preserved Ejection Fraction)
First-line agents: β-blockers (metoprolol, atenolol, bisoprolol, carvedilol) or non-dihydropyridine calcium-channel blockers (diltiazem, verapamil) 1, 2
- Metoprolol: 2.5–5 mg IV bolus over 2 minutes (repeat up to 3 doses); then 25–100 mg orally twice daily 1
- Diltiazem: 0.25 mg/kg IV over 2 minutes (typically 15–20 mg), followed by infusion 5–15 mg/h; oral 60–120 mg three times daily or 120–360 mg extended-release once daily 1, 2
- Verapamil: 40–120 mg three times daily or 120–480 mg extended-release once daily 2
LVEF ≤40% (Reduced Ejection Fraction or Heart Failure)
Use only β-blockers (bisoprolol, carvedilol, long-acting metoprolol) and/or digoxin; avoid diltiazem and verapamil because of negative inotropic effects that may precipitate hemodynamic collapse. 1, 2
- Digoxin: 0.0625–0.25 mg daily orally (or 0.25 mg IV, repeat up to 1.5 mg cumulative in 24 hours) 1
Rate-Control Targets
Aim for lenient resting heart rate <110 bpm initially; pursue stricter control (<80 bpm) only if symptoms persist despite achieving the lenient target. 1, 2 The RACE II trial demonstrated lenient control was non-inferior to strict control. 1
Assess heart rate during exertion, not solely at rest, because many patients have inadequate control during activity despite acceptable resting rates. 1
Combination Therapy When Monotherapy Fails
Add digoxin to a β-blocker or calcium-channel blocker if adequate rate control is not achieved within 4–7 days; combination therapy provides superior control at rest and during exercise compared with either drug alone. 1, 2 Monitor closely for bradycardia. 1
Special Populations
- Chronic obstructive pulmonary disease or active bronchospasm: Use non-dihydropyridine calcium-channel blockers (diltiazem or verapamil) and avoid β-blockers 1, 2
- Wolff-Parkinson-White syndrome with pre-excited AF: NEVER use AV-nodal blockers (adenosine, β-blockers, calcium-channel blockers, digoxin, amiodarone)—they can accelerate ventricular rate and precipitate ventricular fibrillation. Perform immediate DC cardioversion if unstable; if stable, give IV procainamide or ibutilide. 1, 2
Critical Pitfall
Digoxin alone is ineffective for rate control in paroxysmal AF, especially during exercise or sympathetic surges; it should be used only as a second-line agent or in combination. 1
Rhythm Control Considerations
Consider rhythm control for: symptomatic patients despite adequate rate control, younger patients (<65 years) with new-onset AF, first episode in otherwise healthy patients, rate-related cardiomyopathy (newly detected heart failure with rapid ventricular response), or hemodynamically unstable patients. 1, 2, 4
Rhythm control does NOT reduce mortality compared with rate control and is associated with higher hospitalization and adverse drug-effect rates in older patients. 1 The AFFIRM and RACE trials showed no survival advantage. 1
Cardioversion Protocol
For AF lasting >48 hours (or unknown duration), provide therapeutic anticoagulation for ≥3 weeks before elective cardioversion and continue for ≥4 weeks afterward. 1, 2 This applies to both electrical and pharmacological cardioversion. 1
Alternatively, perform transesophageal echocardiography to exclude left-atrial thrombus; if negative, proceed with cardioversion after initiating heparin. 1, 2
Antiarrhythmic Drug Selection (Based on Cardiac Structure)
Selection must be based strictly on LVEF and structural heart disease—class I antiarrhythmics in structural heart disease can cause life-threatening proarrhythmia. 2
| Cardiac Structure | First-Line Agent(s) | Key Contraindications |
|---|---|---|
| No structural heart disease (normal LVEF, no CAD, no LV hypertrophy) | Flecainide, propafenone, or sotalol [1,2] | Avoid in ischemic or structural heart disease [2] |
| Coronary artery disease with LVEF >35% | Sotalol (requires ≥3-day inpatient monitoring) [2] | — |
| Heart failure or LVEF ≤40% | Amiodarone or dofetilide only [1,2] | All other antiarrhythmics carry high proarrhythmic risk [2] |
Amiodarone is reserved for second- or third-line use because of significant extracardiac toxicity (pulmonary fibrosis, hepatic injury, thyroid dysfunction). 1
Catheter Ablation
Catheter ablation is recommended as second-line therapy after failure of antiarrhythmic drugs, or as first-line therapy in selected patients with paroxysmal AF. 1, 2, 4 In patients with heart failure and reduced ejection fraction, ablation improves quality of life, left ventricular function, and reduces mortality and heart failure hospitalizations. 4
Common Pitfalls to Avoid
- Never discontinue anticoagulation solely because sinus rhythm has been restored—stroke risk is determined by CHA₂DS₂-VASc score, not rhythm status 1, 2
- Do not combine β-blockers with diltiazem or verapamil except under specialist supervision—risk of severe bradycardia and heart block 1
- Avoid calcium-channel blockers in LVEF ≤40% or decompensated heart failure—may precipitate hemodynamic collapse 1, 2
- Do not perform catheter ablation without prior trial of medical therapy except in selected patients with paroxysmal AF or HFrEF 1
- Mislabeling AF with rapid rate and wide QRS as ventricular tachycardia—consider AF with aberrancy or pre-excitation 1