Distinction between atrioventricular reciprocating tachycardia and atrioventricular node re-entrant tachycardia in the adult population based on P wave location; should we reconsider the value of some ECG criteria according to gender and age?

Aims: Distinction between atrioventricular node re-entrant tachycardia (AVNRT) and atrioventricular reciprocating tachycardia (AVRT) is sometimes difficult using location of retrograde P waves on ECG.

Methods: P wave location was retrospectively determined in 137 anterior slow-fast AVNRT (85%) and 26 orthodromic AVRT (15%) with narrow QRS occurring in 161 successive patients without pre-excitation. Mechanism of arrhythmia was assessed by electrophysiological study and confirmed by the efficacy of radiofrequency ablation. P waves were classified as invisible, visible after the QRS, or as R' in V(1) and/or S in II. Correlations with arrhythmia mechanism were made according to gender and age (>or= or <65 years old).

Results: Mechanism was related to gender but not to age, with a higher proportion of AVNRT in women (89/97, 91%) than in men (48/66, 72%) (P=0.001). AVRT presented with visible P waves in 26/26 cases (100%) while AVNRT presented with invisible P waves in 36/137 (27%), R'V(1)/SII in 79/137 (57%) and visible P waves in 22/137 (16%). P wave location during AVNRT was related to age but not to gender, with a higher proportion of AVNRT with visible P waves in elderly than in younger patients: 8/27 (29%) vs 14/110 (12%) (P=0.03). Visible P wave during AVNRT was mainly caused by a delay in nodal retrograde conduction in 17/22 patients (77%). Mechanism of tachycardia with visible P waves was related to gender (AVNRT in 14/22 women (64%), AVRT in 18/26 men (70%), P =0.02) and to age, although non-significantly (AVNRT in 8/13 (62%) old vs 14/35 (40%) young patients, P=0.18). A visible P wave was predictive of AVNRT in 25% and in 60% of the men and women younger than 65 years old, and in 50% and in 71% of older men and women respectively (P=0.08 - borderline significance).

Conclusions: Correct distinction between anterior slow-fast AVNRT and orthodromic AVRT can be reliably made regardless of gender or age in case of R'V(1)/SII or invisible P wave. AVRT as the expected mechanism should be reconsidered in the case of visible P waves in the elderly and in the female gender in the absence of pre-excitation.