High-resolution substrate-guided versus linear cavotricuspid isthmus ablation in a randomized near-zero-fluoroscopy trial (Zero MAGIC): interim procedural results

Background Cavotricuspid isthmus (CTI) ablation is the treatment of choice for typical atrial flutter. Conventional linear ablation is effective but time-consuming and still occasionally requires fluoroscopy. High-resolution (HR) mapping with minielectrode (ME) catheters allows maximum-voltage-guided (MVG) substrate ablation that may reduce radiofrequency (RF) burden within a fully fluoroless workflow. Randomized data comparing MVG with standard linear ablation remain limited. Methods Zero MAGIC is an ongoing single-centre randomized trial comparing ME-based MVG with standard linear CTI ablation. All procedures were guided by a 3-D mapping system and aimed for bidirectional CTI block after a 30-min waiting period. Fluoroscopy was intentionally avoided. This interim analysis includes the first 77 patients (MVG n = 42, Linear n = 35). Primary endpoints were cumulative RF duration and energy to achieve CTI block; secondary endpoints were number of RF applications, total procedure duration, fluoroscopy time, and complications. Results Baseline characteristics were comparable (age 68 ± 9 vs 67 ± 11 years; BMI 28.3 ± 4.9 vs 28.3 ± 5.4 kg/m²; male 71 vs 80 %; all p > 0.05). Acute bidirectional CTI block was achieved in 100 % (42/42) MVG and 97 % (34/35) Linear procedures (p = 0.33). Compared with Linear ablation, MVG significantly reduced ablation requirements as in Figure. Conclusion In this randomized near-zero-fluoroscopy trial, HR-based MVG CTI ablation halved RF duration and energy compared with the conventional linear approach, while maintaining identical acute success and safety. These data confirm the procedural efficiency of individualized substrate-guided ablation and support the concept of a completely fluoroless workflow for typical atrial flutter.