What is the recommended acute and long‑term management of atrioventricular nodal re‑entrant tachycardia (AVNRT)?

Treatment of Atrioventricular Nodal Reentrant Tachycardia (AVNRT)

For acute AVNRT, start with vagal maneuvers immediately, followed by IV adenosine if unsuccessful, and reserve IV calcium channel blockers or beta-blockers as third-line agents; for long-term management, catheter ablation of the slow pathway is the definitive first-line treatment, with oral verapamil, diltiazem, or beta-blockers reserved for patients who decline or are not candidates for ablation. 1

Acute Management Algorithm

Hemodynamically Stable Patients

First-line: Vagal Maneuvers

• Vagal maneuvers (Valsalva, carotid massage) are Class I recommended as the initial intervention for all hemodynamically stable AVNRT patients 1, 2
• These should be attempted immediately before any pharmacologic therapy 1

Second-line: Adenosine

• IV adenosine is Class I recommended if vagal maneuvers fail 1, 2
• Adenosine achieves conversion to sinus rhythm in approximately 90% of AVNRT cases 3, 4
• Typical dosing: 6 mg rapid IV push, followed by 12 mg if needed 2
• Common transient side effects include flushing and chest discomfort, but these resolve within seconds 5

Third-line: IV Calcium Channel Blockers or Beta-Blockers

• IV diltiazem or verapamil are Class IIa reasonable alternatives for hemodynamically stable patients 1
• These agents achieve >90% conversion rates comparable to adenosine but with fewer immediate side effects 5
• Diltiazem is FDA-approved specifically for rapid conversion of PSVT including AVNRT 6
• IV beta-blockers (metoprolol, esmolol) are equally reasonable Class IIa options 1
• Critical caveat: Ensure the rhythm is truly AVNRT before administering calcium channel blockers, as these agents are dangerous in ventricular tachycardia or pre-excited atrial fibrillation (Wolff-Parkinson-White syndrome) 2, 6

Fourth-line: IV Amiodarone

• IV amiodarone may be considered (Class IIb) when other therapies are ineffective or contraindicated 1
• This is a lower-priority option given the high efficacy of earlier interventions 1

Hemodynamically Unstable Patients

Immediate synchronized cardioversion is the definitive Class I treatment when AVNRT causes hypotension, altered mental status, signs of shock, acute heart failure, or ongoing chest pain 1, 2

• Do not delay cardioversion to attempt pharmacologic therapy in truly unstable patients 2
• Vagal maneuvers may be attempted only if immediately feasible and the patient remains conscious 2
• Continuous ECG monitoring and blood pressure measurement are mandatory, with defibrillator and emergency equipment readily available 6

Long-Term Management Algorithm

First-Line: Catheter Ablation

Catheter ablation of the slow pathway is Class I recommended as the definitive treatment for symptomatic AVNRT 1, 2

• Success rates exceed 95% with <1% risk of AV block 1, 3
• This is potentially curative and eliminates the need for chronic pharmacologic therapy 1, 7
• Slow-pathway ablation is preferred over fast-pathway ablation because the latter carries higher risk of complete AV block 1, 3
• Radiofrequency ablation is the standard technique; cryoablation has equivalent acute success but higher recurrence rates during long-term follow-up 1

Pharmacologic Alternatives (for patients declining or not candidates for ablation)

First-line pharmacologic agents (Class I):

• Oral verapamil or diltiazem are Class I recommended 1
• Oral beta-blockers are Class I recommended 1
• These agents reduce episode frequency by approximately 50% and are well-tolerated 1
• Important precaution: Avoid calcium channel blockers in patients with systolic heart failure; monitor for bradyarrhythmias and hypotension 1

Second-line pharmacologic agents (Class IIa):

• Flecainide or propafenone are reasonable for patients without structural heart disease or ischemic heart disease when first-line agents are ineffective or contraindicated 1
• Flecainide is FDA-approved for PSVT at starting doses of 50 mg twice daily, increased by 50 mg increments every 4 days to a maximum of 300 mg/day 8
• Critical restriction: Class IC agents are absolutely contraindicated in patients with structural heart disease or prior myocardial infarction due to proarrhythmic risk 8

Third-line pharmacologic agents (Class IIb):

• Oral sotalol, dofetilide, digoxin, or amiodarone may be reasonable when other options have failed 1
• These carry lower efficacy or greater side-effect profiles compared to first-line agents 1

Observation Without Treatment

Clinical follow-up without pharmacologic therapy or ablation is Class IIa reasonable for minimally symptomatic patients 1

• This approach is appropriate when episodes are infrequent, brief, and well-tolerated 1

"Pill-in-the-Pocket" Strategy

Self-administered acute doses of oral beta-blockers, diltiazem, or verapamil may be reasonable (Class IIb) for patients with infrequent, well-tolerated episodes 1

• This strategy allows patients to self-treat occasional episodes without chronic daily medication 1

Key Clinical Pearls and Pitfalls

Diagnostic confirmation:

• AVNRT typically presents with heart rates of 180-200 bpm (range 110-250 bpm) and sudden onset of palpitations often described as "pounding in the neck" 1, 2
• On ECG, P waves are typically obscured by the QRS or appear immediately after it (pseudo-r' in V1) in typical AVNRT 1, 9
• AVNRT is most common in young adults without structural heart disease, with >60% occurring in women 1

Common pitfall:

• Never administer calcium channel blockers or adenosine if there is any possibility of ventricular tachycardia or pre-excited atrial fibrillation (wide-complex tachycardia with irregular rhythm) 2, 6

Post-conversion management:

• After successful acute termination, evaluate the patient for definitive management with catheter ablation 2
• Most patients may be discharged with appropriate cardiology follow-up after successful conversion in the emergency department 5