Clinical Overview

Atrioventricular reentrant tachycardia (AVRT), also called atrioventricular reciprocating tachycardia, is a fast, regular heart rhythm produced by a reentry circuit that uses an accessory pathway — an extra strand of muscle connecting atrium and ventricle outside the AV node — as one limb of the loop and the AV node/His-Purkinje system as the other (StatPearls, Jabbour, Horenstein, and Grossman, 2024). AVRT is the tachycardia itself, not the same thing as either of its two close neighbors on this site. Wolff-Parkinson-White (WPW) syndrome describes the resting-ECG substrate — the short PR interval and delta wave visible on a baseline tracing, plus a documented symptomatic tachyarrhythmia; AVRT is the arrhythmia that substrate produces, and it can occur just as well with a concealed accessory pathway that only conducts retrograde and never shows a delta wave at all, so a patient’s baseline ECG can be completely normal between AVRT episodes. And “supraventricular tachycardia” (SVT) is the broad umbrella term for any regular tachycardia arising above the ventricles; AVRT is one specific reentrant mechanism inside that umbrella, alongside atrioventricular nodal reentrant tachycardia (AVNRT) and others — it is a species, not a synonym for the genus.

Two conduction patterns exist, defined by which limb the impulse travels down first. Orthodromic AVRT, roughly 80-87% of cases, conducts anterogradely through the AV node and His-Purkinje system and retrogradely back up the accessory pathway, producing a narrow-QRS tachycardia. Antidromic AVRT, roughly 5-10% of cases, runs the loop the other way — anterograde down the accessory pathway and retrograde through the AV node — producing a wide, preexcited QRS that can closely mimic ventricular tachycardia (StatPearls, 2024; LITFL, 2022). A premature atrial or ventricular beat arriving at the right moment, when one limb has recovered its excitability and the other has not, is what typically initiates the loop.

AVRT is the most common arrhythmia in patients presenting with tachycardia and a manifest WPW pattern (Cleveland Clinic Journal of Medicine, Barat, Torres Barba, and Ho, 2025) and is the most common type of SVT diagnosed in infants and children, with the highest incidence in the first year of life; roughly 90% of infant cases resolve spontaneously by 12 months of age, though about 30% of those recur between ages 6 and 9 (StatPearls, 2024). In adults, it is the fourth most common SVT type overall — behind atrial fibrillation, atrial flutter, and AVNRT — but accounts for roughly 20-30% of adult reentrant SVTs specifically, making it the second most common reentrant mechanism after AVNRT (Merck Manual Professional, 2024; StatPearls, 2024). Multiple accessory pathways occur in 4-10% of patients, more often in those with Ebstein anomaly of the tricuspid valve (StatPearls, 2024).

Most episodes are hemodynamically tolerated, producing sudden-onset, sudden-offset palpitations, sometimes with dizziness, lightheadedness, chest discomfort, dyspnea, or syncope (StatPearls, 2024; Cleveland Clinic Journal of Medicine, Barat, Torres Barba, and Ho, 2025). The rhythm’s most dangerous scenario is not ordinary AVRT itself but atrial fibrillation conducted rapidly down an antegradely conducting accessory pathway: because the pathway lacks the AV node’s protective rate-limiting, this can produce an extremely rapid ventricular response and, rarely, degenerate to ventricular fibrillation. A shortest pre-excited R-R interval of 250 ms or less during induced atrial fibrillation, or an accessory-pathway effective refractory period of 250 ms or less, marks a pathway capable of that dangerous conduction and is the electrophysiology-lab threshold used for risk stratification (Elendu et al., Annals of Medicine and Surgery, 2025; StatPearls, 2024). Untreated, frequent or incessant AVRT can also cause tachycardia-induced cardiomyopathy over time (StatPearls, 2024).

The underlying substrate is the same congenital accessory pathway discussed on this site’s WPW page; nothing about pathway formation is specific to AVRT beyond the fact that a pathway capable of conducting in at least one direction is what completes the reentry circuit. A concealed pathway (retrograde-conduction-only) cannot cause preexcitation and produces a normal baseline ECG, but it can still sustain orthodromic AVRT — this site’s WPW page covers that pathway-formation detail further.

Interpretation Guide

Key Features:

• Rate: typically 150-250 bpm, with some sources reporting up to 300 bpm for either orthodromic or antidromic AVRT; treat the rate as supporting evidence rather than the primary discriminator, since it overlaps heavily with AVNRT and other reentrant SVTs (StatPearls, 2024; LITFL, 2022)
• Rhythm: regular, with the paroxysmal reentrant signature of abrupt onset and abrupt termination rather than a gradual rate change
• P waves: in orthodromic AVRT, a retrograde P wave is usually visible following the QRS, with an RP interval greater than 70 ms — longer than the RP interval typical of AVNRT, where the retrograde P wave is usually buried in or right at the end of the QRS (StatPearls, 2024; LITFL, 2022). In antidromic AVRT the P wave is often difficult to identify within the wide QRS complex.
• PR interval: not the useful measurement during the tachycardia itself, since the P wave follows the QRS rather than preceding it; the RP interval is what to measure instead
• QRS complex: narrow (under 120 ms) in orthodromic AVRT; wide (120 ms or more), from conduction down the accessory pathway, in antidromic AVRT — a pattern that can closely resemble ventricular tachycardia
• ST segment: not a primary diagnostic feature; assess it on a post-conversion tracing rather than during the tachycardia
• T waves: not a primary diagnostic feature; the retrograde P wave can distort the early ST segment/T wave region enough to be mistaken for a T-wave change
• QT interval: not a defining feature of AVRT; a reliable measurement generally has to wait for conversion
• Other findings: QRS alternans — a beat-to-beat variation in QRS amplitude — may occur in orthodromic AVRT, though it is not specific to AVRT over AVNRT (LITFL, 2022). A bundle branch block ipsilateral to the accessory pathway can lengthen the tachycardia cycle length, a clue to pathway location (StatPearls, 2024). Where a baseline sinus-rhythm tracing exists, check it for a delta wave: its presence identifies a manifest pathway (WPW pattern); its absence does not rule out AVRT, since a concealed pathway produces a normal baseline ECG.

Key Leads

• A comparison tracing in sinus rhythm — not a lead, but the single most useful adjunct available. Whether the accessory pathway is manifest (delta wave present) or concealed (normal baseline ECG) can only be told from a tracing outside the AVRT episode, and that distinction changes what a clinician expects to see if the rhythm degenerates into atrial fibrillation.
• Leads II and V1 — useful for spotting the retrograde P wave that follows the QRS in orthodromic AVRT and comparing its timing and morphology against the same leads’ appearance in sinus rhythm.
• Leads V1-V3 — where a manifest pathway’s delta wave polarity is most informative for judging left- versus right-sided pathway location on the baseline tracing, the same convention used on this site’s WPW page.

This condition is not lead-agnostic: the retrograde P wave and any baseline delta wave both carry lead-specific diagnostic weight.

Differential Diagnosis

• Wolff-Parkinson-White Syndrome — the resting-ECG substrate (short PR interval, delta wave) plus a documented symptomatic tachyarrhythmia; AVRT is the tachyarrhythmia itself. During orthodromic AVRT the delta wave disappears, so the WPW pattern is only visible on a baseline tracing between episodes, and a concealed accessory pathway can produce AVRT with a baseline ECG that never shows a WPW pattern at all.
• Supraventricular Tachycardia — the broad umbrella category for any regular tachycardia arising above the ventricles; AVRT is one reentrant mechanism inside that umbrella. The clue that separates it from the umbrella’s other common reentrant member, AVNRT, is the RP interval: greater than 70 ms with a visible retrograde P wave after the QRS in AVRT, versus a retrograde P wave usually buried in or at the terminal QRS in typical AVNRT.
• Ventricular Preexcitation — this dataset label marks the isolated short-PR-interval-plus-delta-wave pattern on a resting ECG, without reference to any tachyarrhythmia; a manifest accessory pathway produces this pattern at baseline, and AVRT is the reentrant tachycardia episode that same pathway can go on to produce.
• Shortened PR Interval — a short PR interval without a delta wave or QRS widening, reflecting accelerated AV-nodal conduction rather than ventricular preexcitation; a genuinely preexcited baseline (short PR plus a slurred delta-wave upstroke) points toward a manifest pathway capable of AVRT, not this label.
• Ventricular Tachycardia — the differential that matters most when AVRT is antidromic, since a wide, regular tachycardia can look nearly identical to VT. AV dissociation, capture beats, fusion beats, and a QRS wider than 160 ms all favor VT over antidromic AVRT; a wide-complex tachycardia of uncertain origin is treated as VT until proven otherwise.

Treatment Brief

Confirm lead placement and, if possible, capture a full 12-lead strip during the tachycardia and another after it converts — the paired tracings are what let a clinician measure the RP interval, compare against a baseline sinus-rhythm tracing for a delta wave, and confirm which mechanism produced the rhythm. Assess hemodynamic stability first, since stability drives the treatment path more than the rate itself.

For a stable, narrow-complex (orthodromic) AVRT: vagal maneuvers first, then adenosine, which StatPearls reports as roughly 91% effective at terminating paroxysmal SVT; calcium channel blockers or beta-blockers follow if needed (StatPearls, 2024).

The pre-excitation exception. For a wide, irregular tachycardia consistent with atrial fibrillation conducted down an accessory pathway, or for suspected antidromic AVRT, AV-nodal-blocking agents — adenosine, digoxin, beta-blockers, diltiazem, verapamil, and amiodarone — are not recommended and are potentially harmful (Class III), since blocking the AV node can push more conduction down the accessory pathway and risks an extremely rapid ventricular rate (2019 ESC SVT guideline, via ACC Key Points, 2020; StatPearls, 2024). Procainamide is the typical first-line antiarrhythmic in this setting instead (LITFL, 2022; StatPearls, 2024). For an unstable patient in either form, synchronized cardioversion is the treatment; escalate immediately and notify the provider.

For confirmed, symptomatic AVRT, catheter ablation of the accessory pathway is definitive, Class I-recommended treatment, with success rates generally cited above 90% (individual studies report roughly 85-95% initially, approaching 99% when a repeat procedure is needed for a recurrence) and low complication rates, though septal pathways are technically more challenging and carry a higher recurrence rate than other locations (Cleveland Clinic Journal of Medicine, Barat, Torres Barba, and Ho, 2025; Turan, Akdeniz, and Tuzcu, Journal of Cardiovascular Development and Disease, 2025; Elendu et al., Annals of Medicine and Surgery, 2025). Ablation is increasingly considered even for carefully risk-stratified asymptomatic patients with a manifest pathway, particularly competitive athletes.