What are the recommended drug dosages for acute and chronic management of supraventricular tachycardia (SVT) in adults?

Drug Dosages for SVT Management

Adenosine is the first-line drug for acute SVT termination after vagal maneuvers fail, given as 6 mg rapid IV bolus, followed by 12 mg if needed, and can be repeated once more at 12 mg. 1

Acute Management

First-Line: Adenosine

• Initial dose: 6 mg rapid IV bolus over 1-2 seconds, injected as proximal to the heart as possible, followed immediately by rapid saline flush 1
• Second dose: 12 mg rapid IV bolus if no response within 1-2 minutes 1
• Third dose: 12 mg can be repeated one additional time 1
• Higher doses: 18 mg bolus doses have been reported as safe in refractory cases, particularly in patients with impaired venous return (e.g., right heart failure, pulmonary hypertension) 2
• Efficacy: Terminates 85-100% of PSVT episodes involving the AV node and has 91% overall effectiveness 3, 4
• Half-life: 0.6-10 seconds, making adverse effects transient 1, 3

Second-Line Options (if adenosine fails or is contraindicated)

Beta-Blockers (strength of recommendation increased in 2019 ESC guidelines) 1:

• Esmolol: 500 mcg/kg IV bolus over 1 minute, then infusion at 50-300 mcg/kg/min with repeat boluses between dosing increases 1
• Metoprolol tartrate: 2.5-5 mg IV bolus over 2 minutes; can repeat every 10 minutes up to 3 doses 1
• Propranolol: 1 mg IV over 1 minute; can repeat at 2-minute intervals up to 3 doses 1

Calcium Channel Blockers (downgraded but still used) 1:

• Diltiazem: 0.25 mg/kg IV bolus over 2 minutes, then infusion at 5-10 mg/h (up to 15 mg/h) 1
• Verapamil: 5-10 mg (0.075-0.15 mg/kg) IV bolus over 2 minutes; if no response, additional 10 mg after 30 minutes, then infusion at 0.005 mg/kg/min 1

Critical Pitfalls in Acute Management

• Never use verapamil or diltiazem in wide-QRS tachycardias of unknown origin - can cause hemodynamic collapse if ventricular tachycardia 1, 5
• Avoid adenosine in pre-excited atrial fibrillation - can precipitate ventricular fibrillation 1
• Amiodarone and digoxin are no longer recommended for acute narrow-QRS SVT 1
• Sotalol and lidocaine are no longer recommended for wide-QRS tachycardias 1

Chronic/Long-Term Management

First-Line: Catheter Ablation

• Catheter ablation is recommended as first-line therapy with single-procedure success rates of 94.3-98.5% 4
• This is the most effective therapy to prevent recurrent PSVT and should be prioritized over long-term pharmacotherapy 4

Pharmacologic Options (when ablation declined or not feasible)

For AVNRT and AVRT 1:

• Beta-blockers (Class I recommendation)
• Diltiazem or verapamil (Class I, in absence of pre-excitation)
• Flecainide or propafenone (Class IIa, in absence of structural heart disease)
• Amiodarone, dofetilide, or sotalol (Class IIb)
• Digoxin (Class IIb, in absence of pre-excitation)

Important Downgrades 1:

• "Pill-in-the-pocket" approach no longer recommended for AVRT or AVNRT
• Amiodarone, flecainide, propafenone, and sotalol downgraded for both acute and chronic AVNRT treatment
• Propranolol, procainamide, quinidine, and sotalol should not be used during pregnancy 1

Special Populations

Inappropriate Sinus Tachycardia 1:

• Ivabradine alone or combined with beta-blockers (new recommendation, though not EMA-approved for this indication)
• Verapamil/diltiazem no longer recommended 1

Adults with Congenital Heart Disease 1:

• Avoid sotalol as first-line therapy
• Avoid flecainide/propafenone in patients with ventricular dysfunction, severe fibrosis, left bundle branch block, or ischemic/structural heart disease

Key Evidence Hierarchy

The 2019 ESC guidelines 1 represent the most recent comprehensive update, with the 2015 ACC/AHA/HRS guidelines 1 providing complementary dosing details. The major paradigm shift is the strengthened recommendation for adenosine and beta-blockers while downgrading or eliminating many previously used agents (verapamil/diltiazem, amiodarone, digoxin, sotalol) for acute management 1. The evidence strongly supports catheter ablation as definitive first-line therapy for long-term management over pharmacologic options 4.