Can paroxysmal supraventricular tachycardia (PSVT) be reverted with amiodarone (Cordarone), and is it appropriate only after vagal maneuvers and adenosine have failed?

Can Amiodarone (Cordarone) Revert PSVT?

Amiodarone can revert PSVT, but it should only be used as a last-resort agent after vagal maneuvers, adenosine, calcium channel blockers, and beta-blockers have failed or are contraindicated. 1, 2

Treatment Algorithm for Acute PSVT

First-Line Therapy

• Vagal maneuvers (modified Valsalva maneuver) should be attempted first, with a 43% success rate 3
• IV adenosine is the first-line pharmacologic agent if vagal maneuvers fail, with a 91% conversion rate 1, 3, 4
• Adenosine dosing: 6 mg rapid IV bolus, followed by up to two 12 mg boluses if needed 4

Second-Line Therapy

• IV calcium channel blockers (diltiazem 15-20 mg or verapamil 2.5-5 mg IV over 2 minutes) are preferred alternatives with 64-98% conversion rates 2
• IV beta-blockers (such as metoprolol or esmolol) are reasonable alternatives with Class IIa recommendations 1, 2

Third-Line Therapy (Amiodarone)

• Amiodarone is reserved for refractory cases when other agents have failed or are contraindicated 1, 2
• The European Society of Cardiology specifically states: "Amiodarone should be used only when other therapy has failed and then at the lowest effective dose" 1
• Amiodarone is the preferred agent in patients with impaired left ventricular function or heart failure where calcium channel blockers are contraindicated 2

Evidence for Amiodarone Efficacy in PSVT

Clinical Effectiveness

• In a large observational study of 142 consecutive patients with PSVT, IV amiodarone achieved sinus rhythm conversion in 61% of PSVT cases 5
• Mean time to conversion was 1.2 ± 1.2 hours with a mean dose of 220 ± 105 mg 5
• An electrophysiology study showed IV amiodarone (5 mg/kg/min) terminated tachycardia in 7 of 9 patients (78%) 1

Safety Profile

• Amiodarone demonstrated complete safety with no proarrhythmic events or heart failure exacerbation in the acute setting 5
• Only transient first-degree AV block occurred in 2 patients out of 142 5
• Amiodarone is safe in structural heart disease and left ventricular dysfunction, unlike calcium channel blockers 1, 2

Critical Clinical Considerations

When to Consider Amiodarone

• Structural heart disease or heart failure where calcium channel blockers and beta-blockers are contraindicated 1, 2
• Refractory PSVT after failure of adenosine, calcium channel blockers, and beta-blockers 1, 2
• Hemodynamically stable patients who cannot undergo electrical cardioversion 5

Important Contraindications and Warnings

• Never combine amiodarone with verapamil due to severe risk of bradycardia, sinus arrest, heart block, and hemodynamic collapse from additive negative chronotropic effects 6
• Avoid in WPW syndrome with atrial fibrillation as amiodarone can paradoxically accelerate ventricular rates 7
• Amiodarone has significant long-term toxicity and represents third-line prophylactic therapy 7

Common Pitfalls to Avoid

• Do not use amiodarone as first-line therapy when safer, more effective options (adenosine, calcium channel blockers) are available 1, 2
• Always have a defibrillator available when treating SVT with any antiarrhythmic agent 2
• Remember amiodarone's extremely long half-life (weeks to months) creates potential for prolonged drug interactions even after discontinuation 6
• Avoid combining IV calcium channel blockers and beta-blockers without careful monitoring due to potentiated hypotension and bradycardia 2

Hemodynamically Unstable Patients

• Emergent synchronized cardioversion is the treatment of choice for hemodynamically unstable PSVT, not pharmacologic therapy 3, 8
• Amiodarone should not delay electrical cardioversion in unstable patients 1