The VA Relationship After Differential Atrial Overdrive Pacing: A Novel Tool for the Diagnosis of Atrial Tachycardia in the Electrophysiologic Laboratory

INTRODUCTION: Despite recent advances in clinical electrophysiology, diagnosis of atrial tachycardia (AT) originating near Koch's triangle remains challenging. We sought a novel technique for rapid and accurate diagnosis of AT in the electrophysiologic laboratory. METHODS: Sixty-two supraventricular tachycardias including 18 ATs (10 ATs arising from near Koch's triangle), 32 atrioventricular nodal reentrant tachycardias (AVNRTs), and 12 orthodromic reciprocating tachycardias (ORTs) were studied. Overdrive pacing during the tachycardia from different atrial sites was performed, and the maximal difference in the postpacing VA intervals (last captured ventricular electrogram to the earliest atrial electrogram of the initial beat after pacing) among the different pacing sites was calculated (delta-VA interval). RESULTS: The delta-VA intervals were >14 ms in all AT patients and 14 ms and "atrial-atrial-ventricular" response after overdrive ventricular pacing during the tachycardia were diagnostic. However, the "atrial-atrial-ventricular" response criterion was available in only 52% of the patients because of poor ventriculoatrial conduction. CONCLUSIONS: The delta-VA interval was useful for diagnosing AT irrespective of patient conditions such as ventriculoatrial conduction.