Difference in Microembolic Signals Between Flex-Tip Versus Non-Flex-Tip Type Catheters During High-Power Short-Duration Ablation.

Introduction: A novel flex-tip ablation catheter has a distal tip with a unique design, especially for optimized irrigation flow against catheter contact. This study aimed to evaluate the microembolic signals (MESs) during high-power short-duration (HPSD) ablation between flex-tip and non-flex-tip catheters.

Method and results: We retrospectively evaluated 70 patients (39 and 31 with flex-tip and non-flex-tip catheters, respectively) who underwent first-time HPSD radiofrequency ablation with a 50 W-power setting for atrial fibrillation at two institutions. All patients were clinically assessed for MESs using a novel carotid ultrasound-Doppler system throughout pulmonary vein isolation. The numbers of MESs were compared between the two types of catheters. In an experimental study, porcine heart pieces were ablated using two catheters to observe MESs using the same ultrasound evaluation. In the clinical study, 4913 points (2932 and 1981 points in the flex-tip and non-flex-tip groups, respectively) were analyzed. The numbers of MESs, MESs per point, and MESs per second were significantly lower in the flex-tip group than in the non-flex-tip group (123 ± 171 vs. 332 ± 256, p < 0.001; 1.8 ± 2.7 vs. 5.9 ± 4.3, p < 0.001; and 0.1 ± 0.1 vs. 0.2 ± 0.2, p < 0.001, respectively). After propensity score matching analysis in the clinical study with 19 patients in each group, the number of MESs was significantly lower in the flex-tip group than in the non-flex-tip group (152 ± 228 vs. 378 ± 300, p = 0.013), and the difference was most evident in bubble-type MESs (24 [16-96] vs. 185 [79-421], p = 0.023). In the experimental study with eight attempt ablations in each catheter, the number of MESs was significantly lower in the flex-tip group than in the non-flex-tip group (26 ± 14 vs. 58 ± 17, p = 0.002).

Conclusions: Flex-tip catheter ablation significantly reduced MES detections, particularly in the bubble-type MESs, compared with the non-flex-tip catheter ablation at 50 W. This may indicate safe HPSD ablation with the flex-tip type catheter.