The purpose of this study was to describe and identify useful electrocardiographic characteristics to help identify the mechanism of atrial tachycardia (AT) occurring after persistent atrial fibrillation (PsAF) ablation.
Electrocardiographic analysis to help identify the mechanism of AT after PsAF ablation is much limited by the fact that remodeling and ablation alter the normal activation pattern.
All consecutive patients who underwent mapping and ablation of AT after PsAF ablation were included. Surface P waves were analyzed during higher (>2:1) grades of atrioventricular block.
One hundred ninety-six ATs with visible P waves were identified in 127 patients (macro-re-entry in 57%, centrifugal AT in 43%). One-third displayed low-voltage P waves (≤0.1 mV). An isoelectric line >80 ms was more common in centrifugal compared with macro-re-entrant AT (47% vs. 24%; p < 0.001), but its positive predictive value was limited (60%). A minority of peritricuspid ATs displayed the classic saw-tooth pattern (27% [n = 22]). However, the "precordial transition" (a gradual transition from an upright component in lead V ₁ to a negative component with progression across the precordium) remained often observed and specifically identified peritricuspid AT (specificity, 98%; sensitivity, 59%). Only 2 unique features could help identify perimitral AT (n = 60). First, the presence of a negative or negative-positive P-wave in any of leads V ₂ to V ₆ identified perimitral AT with 97% specificity and 30% sensitivity. Second, a "notched" negative component at the beginning of a positive P-wave in the inferior leads specifically identified clockwise perimitral AT (specificity, 98%; sensitivity, 25%).
Only few unique electrocardiographic characteristics help identify the mechanism of AT after PsAF ablation. Knowledge of these characteristics may aid in planning and performing ablation.