Management of Narrow‑Complex Supraventricular Tachycardia (AVNRT)

Immediate Assessment & Risk Stratification

In adults, a narrow‑complex tachycardia rate of 180–200 bpm is typical for atrioventricular nodal re‑entrant tachycardia (AVNRT) and should prompt evaluation for SVT rather than ischemic causes. Class I recommendation (American College of Cardiology/AHA/HRS). 3
Although SVT is rarely fatal, sustained episodes can precipitate heart‑failure, pulmonary edema, or myocardial ischemia; therefore, long‑term control is warranted. Class I recommendation (European Society of Cardiology). 1

Oral verapamil or diltiazem are Class I agents for chronic rate control of AVNRT in patients without reduced left‑ventricular ejection fraction. Level of evidence: high. (American College of Cardiology). 5
Oral β‑blockers are an acceptable alternative for chronic management, offering an excellent safety profile, especially when cardiac imaging is pending. Class I (American College of Cardiology). [2][3]
Calcium‑channel blockers should be avoided in patients with systolic heart failure or reduced ejection fraction, and both CCBs and β‑blockers require monitoring for bradyarrhythmias and hypotension. Class I (American College of Cardiology). [5][6]
AV nodal‑blocking agents must not be used when pre‑excitation (e.g., Wolff‑Parkinson‑White) is present, as they can precipitate ventricular fibrillation in pre‑excited atrial fibrillation. Class I (American College of Cardiology). [5][6]

Vagal maneuvers (modified Valsalva, carotid sinus massage, facial ice‑cold stimulus) are Class I first‑line interventions; they achieve conversion in approximately 27 % of episodes. (American College of Cardiology). [7][8]
If vagal maneuvers fail, intravenous adenosine terminates AVNRT in about 95 % of patients and serves both therapeutic and diagnostic purposes. Class I (American College of Cardiology). [7][5]
For patients who remain tachycardic and are hemodynamically stable, IV β‑blockers, diltiazem, or verapamil are Class IIa options and are effective for conversion to sinus rhythm. (American College of Cardiology). [5][6]
Synchronized cardioversion is a Class I rescue therapy when pharmacologic measures are ineffective or contraindicated. (American College of Cardiology). [7][5]8

Catheter ablation should be offered as a first‑line definitive treatment for AVNRT after shared decision‑making, given its high efficacy (single‑procedure success 94–99 %) and very low complication rates. Class I (European Society of Cardiology, 2019 guideline). 1
The 2015 ACC/AHA/HRS guideline lists ablation as an option alongside pharmacotherapy, reflecting earlier evidence; newer ESC guidance upgrades it to first‑line based on accumulated data. (American College of Cardiology/AHA/HRS). [2][5]

Verapamil or diltiazem must not be administered to patients with suspected ventricular tachycardia or pre‑excited atrial fibrillation, as they can precipitate ventricular fibrillation. Class I (American College of Cardiology). [5][6]
Amiodarone, digoxin, and sotalol are not recommended for acute narrow‑QRS tachycardia management; they have been downgraded or removed from current SVT guidelines. Class III (European Society of Cardiology). 1
Delay in referral to an electrophysiology specialist should be avoided; all patients with SVT warrant specialist evaluation regardless of symptom frequency. (Implicit guideline recommendation).

All statements are based on cited guideline sources and reflect the strength of recommendation where provided.