Monitoring of atrial ablation using cyclic variation of integrated backscatter

Treatment of atrial fibrillation (AF) often relies on radiofrequency ablation (RFA) of atrial tissue. However, current treatment is associated with a >20% recurrence rate, in part due to inadequate monitoring of tissue viability during ablation. Previous work has utilized cyclic variation of integrated backscatter (CVIB) as an early indicator of myocardial recovery from ischemia. Our aim was to demonstrate the use of CVIB to distinguish normal and ablated myocardium. An AcuNav 10F catheter was used to collect radiofrequency signals from the posterior wall of the left atrium of patients before and after RFA for AF. The normalized power spectrum was obtained and integrated backscatter (IB) was extracted across two continuous heart cycles to calculate the average CVIB. Data from 14 patients demonstrated a significant difference in the magnitude of the CVIB before and after ablation (9.0 vs 6.0 dB, p < 0.001). However, no significant changes were identified when evaluating ECG-gated IB values before and after ablation: ventricular end-systole (−9.8 vs −8.6, p = 0.24), atrial end-diastole (−8.2 vs −8.6, p = 0.72) or ventricular end-diastole (−7.7 vs −8.9, p = 0.18). CVIB is able to differentiate normal and ablated myocardium and may be useful in monitoring atrial ablations.