Abstract 10064: Efficiency and Efficacy of Radiofrequency Delivery During Ventricular Tachycardia Ablation: Unipolar Injury as a Novel Marker of Lesion Formation
Introduction: The parameters to accurately determine the efficacy of VT ablation lesions is not known. The development of unipolar injury during delivery of RF energy has the potential to serve as a novel marker of ablation efficacy.
Objective: To report changes in biophysical parameters including loss of capture, EGM (electrogram) reduction, impedance drop (>10Ω) during VT ablation. To assess the predictive value of unipolar injury for effective radiofrequency delivery.
Methods: Data was collected intraprocedurally and retrospectively analyzed on patients undergoing VT ablation using the CARTO mapping system, using both manual and magnetic navigation system ( MNS), with open-irrigation radiofrequency ablation (30-50W, temp limit 45) from Dec 2010 to May 2011. Unipolar injury was present if any ST elevation from baseline was observed on the distal electrode EGMs during ablation. Other parameters analyzed were 10Ω reduction in impedance, bipolar EGM reduction, loss of capture at 10mA.
Results: Data was analyzed in 231 ablation lesions in 17 patients (range 4-32/pt). The frequency of individual biophysical parameter changes were: >10Ω reduction (77.9%), bipolar EGM reduction (65.4%), while loss of capture was least frequently seen (30.2%). An EGM reduction and impedance drop was seen in 53.7% and a change in all 3 parameters was seen in only 17.6% of lesions. Unipolar injury occurred in 75.3% of lesions. Unipolar injury had a sensitivity of 75% and a negative predictive value of 80% for a change in all 3 parameters. When comparing lesions delivered by manual (128) versus MNS (103), there was no difference between all parameter changes.
Conclusion: VT ablation is inefficient as the majority of radiofrequency lesions do not achieve targeted biophysical parameters. Unipolar injury is a novel marker of ablation with a high negative predictive value for effective lesion formation. No differences in biophysical parameter changes were seen between manual and MNS ablation.
- © 2011 by American Heart Association, Inc.