Low peak frequency for predicting and identifying pseudo conduction sites in macro-re-entrant atrial tachycardia: a strategy to avoid ineffective ablation
D R Y Du, F G Q Fan, T ChenAbstract
Background
A primary obstacle in achieving precise ablation for macro-re-entrant atrial tachycardia (MRAT) is discrimination for pseudo conduction sites. In the settings of complex scar with multiple regions, conventional activation and voltage mapping may be misleading. Omnipolar technology mapping with peak frequency (PF) analysis offers a complementary tool.
Objective
This study sought to analyze properties of PF in pseudo conduction sites as well as termination sites, and evaluate the value of PF mapping in guiding ablation.
Methods
This study prospectively enrolled 10 patients (59±8.8 years,60.0% male) undergoing catheter ablation for MRATs. Of these, 5 patients underwent previous pulmonary vein isolation with radiofrequency ablation (except 1 with cryoballoon ablation), 5 patients had a history of cardiac surgical procedure. All MRATs were mapped with the EnSite X™ electroanatomical mapping system and HD Grid™ mapping catheter to gain high-density activation and omnipolar voltage mapping. Pseudo conduction sites of MRAT were defined as locations with typical ablation target characteristics whereas ablation did not terminate MRAT. PF values and omnipolar voltage at pseudo conduction sites were analyzed and compared to the data at ablation termination sites.
Results
Across 14 circuits (5 left, 5 right, 4 bilateral atrial), 19 candidate sites were analyzed. Ablation terminated MRAT at 11 sites and was ineffective at 8. PF values at pseudo conduction sites were significantly lower (178.5±36.3Hz) than the termination sites (270.8±66.0Hz, p=0.0018) and the global atrium (228.1±23.8Hz, p=0.011). Voltage at pseudo conduction sites (0.62±0.28mV) was significantly lower than the termination sites (1.15±0.56mV, p=0.015) and the global atrium (1.12±0.41mV, p=0.011). PF had a significant predictive value for pseudo conduction site (AUC=0.909; 95%CI, 0.779–1.000; p<0.001). A PF cut-off of <197.74Hz provided 75.0% sensitivity and 90.9% specificity.
Conclusion
Peak frequencies at pseudo conduction sites are substantially lower than the termination sites, supporting the potential of PF mapping as an effective tool for identifying pseudo conduction sites in ablation to avoid ineffective ablation.Figure 1