What are the recommendations for cardioversion in Advanced Cardiovascular Life Support (ACLS)?

ACLS Cardioversion Recommendations

Immediate synchronized cardioversion is the definitive treatment for unstable tachyarrhythmias causing hemodynamic compromise, and should be performed without delay when patients present with acute altered mental status, ischemic chest discomfort, acute heart failure, hypotension, or other signs of shock. 1

Indications for Immediate Cardioversion

Unstable Patients (Class I Recommendation)

• Perform immediate synchronized cardioversion for any tachyarrhythmia causing hemodynamic instability, including acute altered mental status, ischemic chest pain, acute heart failure, hypotension, or shock that persists despite adequate airway and breathing support. 1
• Provide sedation in conscious patients before cardioversion, but do not delay the procedure if the patient is critically unstable. 1
• For atrial fibrillation or atrial flutter with hemodynamic instability (angina, MI, shock, pulmonary edema), cardioverse immediately without waiting for anticoagulation if duration is less than 48 hours. 1

Ventricular Tachycardia

• Direct current cardioversion is mandatory for sustained VT with hemodynamic instability (Class I, Level C). 1
• For wide-complex tachycardia in hemodynamically stable patients, electrical cardioversion should be first-line approach. 1
• Start defibrillation at maximum output for cardiac arrest due to ventricular tachyarrhythmias. 1

Supraventricular Tachycardia

• Synchronized cardioversion is required for hemodynamically unstable SVT when vagal maneuvers or adenosine are ineffective or not feasible (Class I, Level B-NR). 1
• For stable SVT, cardioversion is recommended when pharmacological therapy is ineffective or contraindicated (Class I, Level B-NR). 1
• In select cases of regular narrow-complex tachycardia with unstable signs, a trial of adenosine before cardioversion is reasonable (Class IIb, Level C), but this should not delay definitive treatment. 1

Anticoagulation Requirements

Duration-Based Protocol

• For AF/atrial flutter ≥48 hours or unknown duration: Require therapeutic anticoagulation (INR 2.0-3.0) for at least 3 weeks before and 4 weeks after cardioversion (Class I, Level B). 1
• For AF/atrial flutter >48 hours requiring immediate cardioversion due to hemodynamic instability: Administer IV heparin bolus followed by continuous infusion (aPTT 1.5-2 times control), then oral anticoagulation for at least 4 weeks post-procedure (Class I, Level C). 1
• For AF <48 hours with hemodynamic instability: Cardiovert immediately without prior anticoagulation (Class I, Level C). 1

TEE-Guided Approach

• Transesophageal echocardiography is recommended if 3 weeks of therapeutic anticoagulation has not been provided, to exclude cardiac thrombus and enable early cardioversion (Class I, Level B). 1
• If no thrombus identified on TEE, cardioversion is reasonable immediately after initiating anticoagulation with unfractionated heparin (Class IIa, Level B). 1

Energy Selection and Technique

Synchronized Cardioversion

• Use synchronized mode for all organized rhythms (atrial fibrillation, atrial flutter, SVT, stable VT) to avoid delivering shock during vulnerable period of cardiac cycle. 1
• Ensure proper electrode placement: Ideally at least 8 cm from ICD generator if present. 1

Unsynchronized Defibrillation

• Use unsynchronized shocks only for pulseless VT or ventricular fibrillation. 1
• Start at maximum output for cardiac arrest situations. 1

Pharmacological Adjuncts

Pre-Treatment to Enhance Success

• Pretreatment with amiodarone, flecainide, ibutilide, propafenone, or sotalol can enhance cardioversion success and prevent early AF recurrence (Class IIa, Level B). 1
• IV amiodarone may facilitate defibrillation and prevent VT/VF recurrences in acute situations. 1

Post-Cardioversion Maintenance

• Continue oral anticoagulation for at least 4 weeks in all patients after cardioversion, and long-term in those with thromboembolic risk factors regardless of rhythm outcome (Class I, Level B). 1

Critical Contraindications

• Electrical cardioversion is contraindicated in digitalis toxicity or hypokalemia (Class III, Level C). 1
• Do not use verapamil for wide-complex tachycardias unless known to be supraventricular origin (Class III, Level B). 1
• Adenosine should not be given for unstable or irregular/polymorphic wide-complex tachycardias, as it may cause degeneration to VF (Class III, Level C). 1

Common Pitfalls to Avoid

• Never delay cardioversion in hemodynamically unstable patients to obtain anticoagulation when AF duration is uncertain but instability is present. 1
• Do not perform frequent repetitive cardioversions in patients with short sinus rhythm periods between relapses despite prophylactic antiarrhythmic therapy (Class III, Level C). 1
• Ensure adequate sedation in conscious patients to minimize discomfort and patient movement during shock delivery. 1
• Monitor for post-cardioversion complications including bradycardia, heart block, and thromboembolic events. 2, 3