What is the immediate management of a hemodynamically unstable patient with atrial fibrillation and rapid ventricular response?

Immediate Management of Hemodynamically Unstable Atrial Fibrillation with Rapid Ventricular Response

Perform immediate synchronized electrical cardioversion without waiting for anticoagulation in any patient with atrial fibrillation causing hemodynamic instability—this is the definitive first-line treatment and delays increase mortality. 1, 2

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Recognize Hemodynamic Instability

Hemodynamic instability in AFib with RVR is defined by any of the following:

• Symptomatic hypotension (systolic blood pressure < 90 mmHg) 2, 3
• Acute decompensated heart failure or pulmonary edema 2
• Ongoing myocardial ischemia or infarction (chest pain, ST changes, elevated troponin) 1, 2
• Altered mental status from hypoperfusion 2
• Cardiogenic shock 4, 2

Do not delay cardioversion to achieve therapeutic anticoagulation in these patients—this increases mortality. 2

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Immediate Synchronized Electrical Cardioversion

• Deliver synchronized biphasic electrical cardioversion starting at 120–200 J (or higher if initial attempts fail). 4, 5
• Synchronization is mandatory to avoid inducing ventricular fibrillation by delivering a shock during the vulnerable period of the cardiac cycle. 2
• Administer procedural sedation (e.g., IV midazolam and/or propofol) for conscious patients, with continuous cardiac monitoring during and for at least 2 hours post-cardioversion. 4

If Initial Cardioversion Fails

• Repeat cardioversion at escalating energy levels (up to 360 J monophasic or maximum biphasic output). 6
• Consider double-dose external cardioversion using two defibrillators simultaneously (total 720 J) if single-device attempts at maximum energy fail. 6
• Administer IV class III antiarrhythmic pretreatment (e.g., ibutilide or amiodarone) to facilitate electrical conversion and suppress immediate AF recurrence if initial shocks are unsuccessful. 1, 7

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Concurrent Anticoagulation

• Administer intravenous unfractionated heparin as a bolus (60–80 units/kg, max 5000 units) followed by continuous infusion (12–18 units/kg/h, targeting aPTT 1.5–2 times control) at the time of or immediately after cardioversion if feasible. 1, 2
• Continue oral anticoagulation (warfarin INR 2.0–3.0 or a direct oral anticoagulant) for at least 4 weeks post-cardioversion regardless of whether sinus rhythm is maintained. 1, 2
• Long-term anticoagulation decisions are based on CHA₂DS₂-VASc score, not rhythm status—patients with a score ≥2 (men) or ≥3 (women) require indefinite anticoagulation. 4, 2

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Special Clinical Scenarios Requiring Modified Approach

Wolff-Parkinson-White Syndrome with Pre-Excitation

• If hemodynamically unstable, perform immediate electrical cardioversion. 1, 2
• If hemodynamically stable, administer IV procainamide or ibutilide (not AV nodal blockers). 1, 4
• Never use AV nodal blocking agents (beta-blockers, calcium-channel blockers, digoxin, adenosine, amiodarone) in WPW with pre-excited AFib—they can paradoxically accelerate ventricular rate and precipitate ventricular fibrillation. 1, 4, 2
• Catheter ablation of the accessory pathway is definitive treatment for symptomatic patients. 1, 5

Acute Myocardial Infarction

• Perform electrical cardioversion for severe hemodynamic compromise or intractable ischemia. 1, 2
• Administer IV beta-blockers (if no LV dysfunction, bronchospasm, or AV block) or IV digoxin/amiodarone to slow ventricular response and improve LV function. 1
• Heparin anticoagulation is mandatory unless contraindicated. 1
• Never use type IC antiarrhythmic drugs (flecainide, propafenone) in the setting of acute MI or structural heart disease. 1, 2

Pregnancy

• Electrical cardioversion is safe and should not be delayed for hemodynamic instability. 2
• Unfractionated heparin is preferred during the first trimester and last month of pregnancy. 1, 2

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Post-Cardioversion Rate Control (If AFib Recurs)

Preserved Ejection Fraction (LVEF > 40%)

• Use IV beta-blockers (metoprolol 2.5–5 mg IV over 2 min, repeat up to 3 doses) or non-dihydropyridine calcium-channel blockers (diltiazem 0.25 mg/kg IV over 2 min, then infusion 5–15 mg/h). 4, 2
• Target a lenient resting heart rate < 110 bpm initially; pursue stricter control (< 80 bpm) only if symptoms persist. 4

Reduced Ejection Fraction (LVEF ≤ 40%) or Heart Failure

• Use beta-blockers (bisoprolol, carvedilol, long-acting metoprolol) and/or digoxin only—avoid calcium-channel blockers due to negative inotropic effects. 4, 2
• If monotherapy fails, combine digoxin with a beta-blocker for superior rate control at rest and during exercise. 4

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Antiarrhythmic Therapy to Maintain Sinus Rhythm

No Structural Heart Disease (Normal LVEF, No CAD, No LV Hypertrophy)

• First-line agents: flecainide, propafenone, or sotalol. 4, 2

Coronary Artery Disease with LVEF > 35%

• Sotalol is preferred; requires hospitalization with continuous ECG monitoring for ≥3 days and dose adjustment for renal function. 4

Heart Failure or LVEF ≤ 40%

• Amiodarone is the only safe option due to high pro-arrhythmic risk of other agents. 4, 2

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Critical Pitfalls to Avoid

• Never delay cardioversion to achieve therapeutic anticoagulation in hemodynamically unstable patients—this increases mortality. 2
• Never use AV nodal blockers in suspected WPW with wide-complex AFib—this can be fatal. 1, 2
• Never use type IC drugs in acute MI or structural heart disease. 1, 2
• Do not discontinue anticoagulation after successful cardioversion in patients with stroke risk factors—stroke risk is determined by CHA₂DS₂-VASc score, not rhythm status. 4, 2