Reply to the Editor— Contact force–sensing catheters and increased risk of atrioesophageal fistula: Is the tool to blame or the workmen?

We appreciate the interest and comments expressed by Das et al on force-time integral (FTI) targets for catheter ablation and the risk of atrioesophageal fistula formation. We agree that the application of a single FTI target to all areas of the left atrium is suboptimal (and potentially harmful) because of the variation in wall thickness and tissue architecture. It is certainly possible that targeting an FTI of 400 gs when ablating on the thin posterior wall may contribute to an increased risk of atrioesophageal fistula. We believe that there is a tremendous gap in knowledge, with few, if any, data to guide power and contact force delivery on the posterior wall. Das et al make an important contribution by identifying that an FTI of ≥230 gs on the posterior wall has a positive predictive value of 98.6% for no reconnection. However, validation of this threshold and other indices is needed, including those that incorporate power delivery. The use of acoustic radiation force imaging is one such way to validate these thresholds in vivo. However, analyses of large numbers of cases with specific data on ablation delivery during the procedure and postablation outcomes are needed. Centralization of ablation data from electroanatomic mapping systems linked to postprocedure outcomes via national ablation registries would help answer these important safety and efficacy questions. Ultimately, contact force–sensing catheters are an important advance in atrial fibrillation ablation. The “blame” raised by Das et al does not lie with the tools, nor with the workmen. However, the absence of durable data to guide ablation on the posterior wall is a significant impediment to optimal efficacy and safety of atrial fibrillation ablation.