What mapping strategy is used for Antidromic AVRT?

• A. Pace V map to earliest A
• B. Pace H map to earliest V
• C. Pace A map to earliest V
• D. Pace A map to latest V

Answer: (C)

Antidromic AVRT uses the accessory pathway to conduct the impulse from the atria to the ventricles. To locate that pathway, pace from the atrium and map to the earliest ventricular activation. The first ventricular site that activates indicates where the impulse enters the ventricle via the accessory pathway, revealing the AP insertion. This direct approach targets the antegrade limb of the antidromic circuit, making it the most informative strategy. Pacing the ventricle or the His bundle would trace other pathways (retrograde conduction or the His–Purkinje system) and not pinpoint the accessory pathway location. Pacing from the atrium to the latest ventricular activation wouldn’t correctly identify the AP entrance.