Abstract 2200: Variability in Post-pacing Intervals Predicts Global Atrial Activation Pattern During Tachycardia

Abstract

Background: Knowledge of the global atrial activation pattern is critical to ablation of an atrial arrhythmia. We hypothesized that the variability in post-pacing intervals (PPI) with pacing at different cycle lengths (CL) from the same pacing site, regardless of distance to the circuit, can be used to identify atrial activation patterns during tachycardia. Methods and Results: Patients referred for ablation of SVT were included (n=28, 31 total tachycardias). During tachycardia, overdrive atrial pacing was performed. The variability in PPIs (PPIV) was calculated by comparing the difference in PPIs after overdrive pacing at trains 10, 20, and 30 ms shorter than the tachycardia cycle length (TCL). The global activation pattern was defined as circuitous (grossly visible circuit) or centrifugal (focal origin with centrifugal radiation) by electroanatomic mapping. Except for one case, all pacing was performed from the proximal CS bipole. Circuitous tachycardias exhibited minimal variability with pacing at 10 ms and 30 ms shorter than TCL (6.0±2.5 ms), whereas centrifugal tachycardias displayed a high degree of variability (56.5±20.6 ms, 8 of 14 were micro-reentrant). Rank sum analysis of PPIV suggests that the two groups are indeed distinct (P<0.001). Using PPIV cutoffs of ≤10 ms and ≥30 ms, circuitous and centrifugal activation patterns were classified with a high degree of sensitivity (94% circuitous, 92.8% centrifugal) and 100% specificity. Conclusion: Our data supports the use of PPIV to rapidly and accurately predict global activation pattern during atrial arrhythmia.