Background: Pulmonary vein isolation is the most prevalent approach for catheter ablation of paroxysmal atrial fibrillation. Long-term success of the procedure is diminished by arrhythmia recurrences occurring predominantly because of reconnections in previously isolated pulmonary veins. The aim of the EFFICAS I multicenter study was to demonstrate the correlation between contact force (CF) parameters during initial procedure and the incidence of isolation gaps (gap) at 3-month follow-up.
Method and results: A radiofrequency ablation catheter with integrated CF sensor (TactiCath, Endosense, Geneva, Switzerland) was used to perform pulmonary vein isolation in 46 patients with paroxysmal atrial fibrillation. During the ablation procedure, the operator was blinded to CF information. At follow-up, an interventional diagnostic procedure was performed to assess gap location as correlated to index procedure ablation parameters. At follow-up, 65% (26/40) of patients showed ≥1 gaps. Ablations with minimum Force-Time Integral (FTI) <400 gs showed increased likelihood for reconnection (P<0.001). Reconnection correlated strongly with minimum CF (P<0.0001) and minimum FTI (P=0.0007) at the site of gap. Gap occurrence showed a strong trend with lower average CF and average FTI. CF and FTI are generally higher on the right side, although the left anterior segment presents a unique challenge to achieve stable position with good CF.
Conclusions: Minimum CF and minimum FTI values are strong predictors of gap formation. Optimal CF parameter recommendations are a target CF of 20 g and a minimum FTI of 400 gs for each new lesion.