Contact Index for PulseSelect Catheter Apposition: Validation by Transesophageal Echocardiography

BACKGROUND: Reliable catheter-tissue apposition is important for effective pulmonary vein isolation using pulsed field ablation. The contact index, derived from real-time impedance rise on the EnSite X mapping system, may provide an objective surrogate for catheter contact; however, its utility with the PulseSelect catheter remains insufficiently defined. METHODS: In this single-center pilot study, patients with paroxysmal atrial fibrillation undergoing pulmonary vein isolation with the PulseSelect catheter under general anesthesia were evaluated. High-resolution transesophageal echocardiography was used as the reference standard to classify electrode-level catheter apposition as contact or non-contact. Contact index values from electrodes 3-7 were paired with transesophageal echocardiography findings, and receiver operating characteristic curve analysis was performed. RESULTS: A total of 316 paired imaging-electrical data points were analyzed. Interobserver agreement for transesophageal echocardiography-based contact assessment was excellent (Cohen's κ = 0.86). Contact index values were higher at contact than non-contact segments. A contact index cutoff of 10% yielded an area under the curve of 0.864, with 76.1% sensitivity and 82.9% specificity. In the central electrodes 4-6, the area under the curve was 0.871, with 80.1% sensitivity and 81.2% specificity. CONCLUSIONS: Contact index was associated with transesophageal echocardiography-confirmed catheter-tissue apposition during pulsed field ablation using the PulseSelect catheter. A 10% threshold may be a useful candidate reference for real-time apposition assessment, requiring validation in larger studies.