Usefulness of retrograde P waves for differentiating supraventricular tachycardia

Song, Jong Min; Choi, Yun Shik; Chae, In Ho; Kim, Hyo Soo; Sohn, Dae Won; Oh, Byung Hee; Lee, Myoung Mook; Park, Young Bae; Lee, Young Woo

Abstract

BACKGROUND
Retrograde P wave can be found not only in atrioventricular reentrant tachycardia (AVRT) but also in atrioventricular nodal reentrant tachycardia (AVNRT), especially of posterior-type. This study evaluated the usefulness of retrograde P wave for differentiating AVNRT from concealed AVRT and for localization of accessory pathway(AP).
METHODS
Twelve lead ECGs were analyzed in patients with AVNRT (n=41) and concealed AVRT (n=53) who have taken successful ablation. Presence of pseudo r' in V1, pseudo S in II, III, aVF, and configuration and polarity of presumed retrograde P waves were evaluated. RP was obtained by subtracting RP interval in III from that in V1.
RESULTS
In anterior-type AVNRTs (n=38), there were no retrograde P wave in 53% and the pseudo r' and/or S in 47%. Retrograde P waves in V1 were positive in 67% (2/3 cases) of posterior-type AVNRTs and 97.4% (37/38 cases) of AVRTs with left free wall AP, but negative in 83.3% (5/6 cases) of AVRTs with right free wall AP. Retrograde P waves in II, III, aVF were negative in all of posterior-type AVNRTs, all with left and right posteroseptal AP, right posterior AP, and 90% (9/10 cases) with left posterior AP. All with left anterior and right anteroseptal AP showed positive P wave in III. RP of posterior-type AVNRT was significantly larger than those with left posteroseptal or left posterior AP (p<0.01). Sensitivity of newly developed stepwise algorithm was 50-100%.
CONCLUSION
Retrograde P wave during tachycardia on standard ECG is very useful for differentiation of AVNRT from concealed AVRT and also for localization of APs.