Buttu A. 1 , Van Zaen J. 1 , Viso A. 1 ,

1. Termination of Atrial Fibrillation by Catheter Ablation Can Be Successfully Predicted from Baseline ECG Buttu A.1, Van Zaen J.1, Viso A.1, Forclaz A.2, Pascale P.2, Narayan S.3, Vesin J.1, Pruvot E.2 1Applied Signal Processing Group, Swiss Federal Institute of Technology EPFL, Lausanne – Switzerland 2Department of Cardiology, University Hospital Center Vaudois CHUV, Lausanne – Switzerland 3University of California, San Diego - USA

2. Introduction • The success rate of stepwise radiofrequency ablation (step-CA) for patients (pts) with long-standing persistent atrial fibrillation (LS-pAF) appears limited. • Multiple parameters have been used to predict the outcome of step-CA (AF cycle length – AFCL, AF duration..). • Limited success. • Aim of our study: • To develop innovative indices from baseline ECG recordings (i.e. before ablation) that can predict the termination of AF during step-CA.

3. Methods • 17 consecutive male patients included. • Clinical characteristics:

4. Methods • Electrophysiological study: • Effective anticoagulation therapy for > 1 month. • Antiarrhythmic drugs (except amiodaroneand beta-blockers) were discontinued 5 half-lives before the procedure. • General anesthesia. • Catheter for mapping and ablation: 3.5 mm cooled-tip Navistar(Webster). • Chest lead V6 was placed in the back (V6b), within the cardiac silhouette.

5. Methods • Ablation protocol: • Procedural end point: • Termination of AF into sinus rhythm (SR) or atrial tachycardia (AT). • Non terminated AF were cardioverted electrically.

6. Methods • Signal processing: adaptive harmonic frequency tracking Power spectrum density Dominant frequency? How to extract the frequency content? Time-frequency representation First harmonic Adaptive harmonic frequency tracking Dominant frequency

7. Methods

8. Methods – Organization Measurements • Two organization measurements: • Adaptive organization index (AOI): ratio between the power of the extracted components and the total power of the signal. Quantifies the cyclicityof the oscillations Mean 0.7 =

9. Methods – Organization Measurements • Variance of the phase difference (PD): variance of the slope of the phase difference. Quantifies the regularity of the oscillations Variance = 6.5 · 10-6

10. Methods • AOI and PD were compared to classical indices: • AFCL computed from the inverse of the dominant frequency (classical method) of chest leads V1 and V6b after QRST cancellation2. • Organization index (OI)1: ratio of the power in a 1-Hz band centered on the dominant peak to the total power in the spectrum (FFT). • All the considered measures were computed from 10-sec ECG recordings at baseline, after QRST cancellation2. OI = 0.24 1 – Everett T. H. et al. IEEE J BME 2001; 48; 969-78 2 – Lemay M. et al. IEE Trans Biomed Eng2007; 54; 542-6

11. Results

12. Results

13. Conclusions • Adaptive algorithms based on the instantaneous tracking of the dominant frequency (and its harmonics) improve the assessment of organization during AF. • Our findings are suggestive of a higher baseline bi-atrial organization in LT patients. • Innovative adaptive indices appear as promising parameters to predict patients that can be left terminated. • Validation on a larger population is needed.

14. Thank you

15. Ventricular activity cancellation • Improves the reliability of ECG analysis during AF. • Single-beat method2: • QRS complexes and T-waves are treated separetly: • QRS cancellation is an interpolation of atrial activity with weighted sinusoids. • T-wave cancellation based on a dominant T-wave approach. • Advantages: • Independent of the length the ECG recording. • No discontinuities and QRS residues in the resulting signals. 2 – Lemay M. et al. IEE Trans Biomed Eng2007; 54; 542-6

16. Ventricular activity cancellation • Example (signal duration 10-sec, sampling frequency: 1kHz): Chest lead V1 Sample Frequency (Hz)

17. Ventricular activity cancellation • Example (signal duration 10-sec, sampling frequency: 1kHz): Dorsal lead V6b Sample Frequency (Hz)

18. Study presented at HRS 2012: “Contribution of Left and Right Atrial Appendage Activities to ECG Fibrillation Waves”. • Methods: • Clinical characteristics: prior to ablation, catheters (CAT) were introduced in 10 consecutive patients (60±5 y, continuous AF duration 22±14 m): • Quadripolar CAT in the RAA. • Decapolar CAT in the coronary sinus (CS). • Dudecapolar CAT in the LAA. • 10-sec epochs for a total duration of 270 sec were used

19. Signal processing: • EGMs: automatic computation of AFCL from LAA, RAA and CS recordings. • ECG: after QRST cancellation, computation of AFCL on all chest leads (V1 to V6b). • Correlation: using Pearson’s correlation coefficient, the correlation between AFCL was computed for each combination of chest leads and EGMs.

20. Results • RAA AFCL was best correlated with chest lead V1 (R = 0.96) and progressively dropped until V5 (R = 0.26). • Interestingly, LAA AFCL showed the opposite pattern with the highest correlation in V6b (R = 0.95) and the lowest one in V2 (R = 0.26).  V1 reflects the activity from the RAA and the dorsal lead V6b reflects the LAA activity

21. Clinical results • Sites of AF termination for LT and RT