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Reliability of luminal oesophageal temperature monitoring during radiofrequency ablation of atrial fibrillation: insights from probe visualization and oesophageal reconstruction using magnetic resonance imaging

Aims
A current concept to prevent atrio-oesophageal fistula during radiofrequency (RF) catheter ablation of atrial fibrillation is to monitor luminal oesophageal temperature (LET). The objective of this study was to describe the temporal course of LET and to assess the reliability of monitoring the maximal LET during pulmonary vein isolation (PVI) using irrigated multi-electrode (IMEA, nMARQTM) and focal ablation catheters.


Methods and results
We studied 40 patients with LET monitoring during PVI (20 patients using the IMEA and 20 patients using the focal catheter). A linear probe was used and visualized in the 3D mapping system. Left atrial and oesophageal reconstructions from delayed enhanced magnetic resonance imaging were integrated. Analysing 745 temperature profiles, LET >38°C was observed in 48 of 296 (17%) and 44 of 449 (10%) ablations for the IMEA and the focal catheter, respectively (P = 0.012). Temporal latency after interruption of RF energy delivery was observed for both catheters. Time until LET baseline temperature was restored after an increase of >1°C was 100 and 86 s for the IMEA and the focal catheter, respectively (P = 0.183). Imprecise representation of the maximal LET was observed in 24 (60%) and 28 patients (70%) for the left and right PVs, respectively.


Conclusion
Due to the unknown exact lateral position of the LET probe within the oesophagus, the measured temperature does not necessarily reflect the maximal LET. The absence of LET increase does not rule out significant temperature increase within the oesophagus. Consequently, the temperature information of the linear multipolar probe should be used with caution.