Cardiostim 2012 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 1 Applied Signal Processing Group, Swiss Federal Institute of Technology EPFL, Lausanne – Switzerland 2 Department of Cardiology, University Hospital Center Vaudois CHUV, Lausanne – Switzerland 3 University of California, San Diego - USA

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.

Methods 17 consecutive male patients included. Clinical characteristics: Study population Age (y) 60 ± 5 AF duration (y) 7 ± 5 Sustained AF (month) 21 ± 13 BMI (kg/m 2 ) 30 ± 6 LVEF (%) 48 ± 11 LA volume (ml) 173 ± 37

Methods Electrophysiological study: Effective anticoagulation therapy for > 1 month. Antiarrhythmic drugs (except amiodarone and 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 V 6 was placed in the back (V 6b ), within the cardiac silhouette.

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

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

Methods

Methods – Organization Measurements Quantifies the cyclicity of the oscillations Two organization measurements: 1.Adaptive organization index (AOI): ratio between the power of the extracted components and the total power of the signal. Mean 0.7 =

Methods – Organization Measurements 2.Variance of the phase difference (PD): variance of the slope of the phase difference. Variance = 6.5 · Quantifies the regularity of the oscillations

Methods AOI and PD were compared to classical indices: AFCL computed from the inverse of the dominant frequency (classical method) of chest leads V 1 and V 6b after QRST cancellation 2. 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 cancellation 2. 1 – Everett T. H. et al. IEEE J BME 2001; 48; – Lemay M. et al. IEE Trans Biomed Eng 2007; 54; OI = 0.24

Results Study population Left terminated (LT = 11, 65%) Right terminated (RT = 2, 12%) Not terminated (NT = 4, 23%) Age (y) 60 ± 5 59 ± 657 ± 163 ± 5 AF duration (y) 7 ± 5 8 ± 67 ± 04 ± 2 Sustained AF (month) 21 ± ± 811 ± 239 ± 11 BMI (kg/m 2 ) 30 ± 6 32 ± 628 ± 427 ±7 LVEF (%) 48 ± ± 1058 ± 454 ± 13 LA volume (ml) 173 ± ± ± ± 33 Cumulative ablation time (min) 55 ± ± 1163 ± 2165 ± 15

Results

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.

Thank you

Ventricular activity cancellation Improves the reliability of ECG analysis during AF. Single-beat method 2 : 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 Eng 2007; 54; 542-6

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

Ventricular activity cancellation Example (signal duration 10-sec, sampling frequency: 1kHz): Dorsal lead V 6b Sample Frequency (Hz)

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): 1.Quadripolar CAT in the RAA. 2.Decapolar CAT in the coronary sinus (CS). 3.Dudecapolar CAT in the LAA. 10-sec epochs for a total duration of 270 sec were used

Signal processing: EGMs: automatic computation of AFCL from LAA, RAA and CS recordings. ECG: after QRST cancellation, computation of AFCL on all chest leads (V 1 to V 6b ). Correlation: using Pearson’s correlation coefficient, the correlation between AFCL was computed for each combination of chest leads and EGMs.

Results RAA AFCL was best correlated with chest lead V 1 (R = 0.96) and progressively dropped until V 5 (R = 0.26). Interestingly, LAA AFCL showed the opposite pattern with the highest correlation in V 6b (R = 0.95) and the lowest one in V 2 (R = 0.26).  V1 reflects the activity from the RAA and the dorsal lead V6b reflects the LAA activity

Clinical results Sites of AF termination for LT and RT Left terminated (LT = 11, 65%) Right terminated (RT = 2, 12%) Left Atrium Roof 2 LAA 1 Coronary sinus 2 Mitral isthmus 6 Right Atrium Cavotricuspid isthmus 1 RAA 1