Simple electrocardiographic criteria for identifying the site of origin of focal right atrial tachycardia.

UNLABELLED

To construct an algorithm for identifying the precise site of origin of focal right atrial tachycardia (RAT), we analyzed the P wave configuration in 32 patients with RAT who underwent successful radiofrequency catheter ablation. The RA was divided into three areas in the left anterior oblique view: superolateral, inferolateral, and inferomedial. There were 17 RATs arising from the crista terminalis (CT-AT), 12 from the tricuspid annulus (TA-AT), and 3 from the septum away from the TA (Sep-AT). A negative P wave in lead aVR identified CT-AT with a sensitivity (sens) of 100% and a specificity (spec) of 93%. In CT-ATs, positive P waves in the inferior leads differentiated superolateral AT from inferolateral AT with a sens of 86% and a spec of 100%. In any type of AT with inferomedial or inferolateral foci, the P wave deflections in at least one of the inferior leads was negative, and negative P waves in leads V5 and V6 identified inferomedial AT with a sens of 92% and a spec of 100%. In ATs near the apex of Koch's triangle, the P wave duration in the inferior leads was shorter than during sinus rhythm.

CONCLUSIONS

(1) the P wave configuration in lead aVR can easily differentiate CT-AT from TA-AT and Sep-AT; (2) the P wave configuration in the inferior leads helps to determine a superior versus inferior origin in any type of AT; (3) in inferior AT, the P wave polarity in leads V5 and V6 is useful in determining a lateral versus medial origin; (4) this algorithm can predict accurately the origin of AT.