Background: Radiofrequency ablation (RFA) of the cavotricuspid isthmus (CTI) is an established therapy for typical atrial flutter. Previous studies have demonstrated that the CTI is often composed of discrete muscle bundles, and evidence has suggested that these bundles correlate with high-voltage local electrograms in the tricuspid isthmus. This randomized, multicenter clinical trial was designed to prospectively compare the hypothesis that a maximum voltage-guided (MVG) technique targets critical conducting bundles in the isthmus, as reflected by a reduction in ablation requirements compared to the anatomical approach to atrial flutter ablation.
Methods: Bidirectional block was achieved in patients undergoing ablation for typical atrial flutter using 1 of 2 randomly assigned methods. The anatomical approach produced a contiguous line of ablation lesions from the inferior aspect of the tricuspid annulus to the inferior vena cava using a standard method. The MVG technique sequentially targeted the maximum voltage local electrograms in the CTI along a similar line.
Results: Sixty-nine patients were randomized, with mean age 63 +/- 10 and 58 (84%) male. Among patients in the anatomic group (n = 34), mean ablation time was 11.2 +/- 7.5 minutes compared to 5.9 +/- 3.3 in the MVG group (n = 35) (P = 0.0026). A mean of 14.2 +/- 9.7 ablation lesions were created in the anatomic group, and 7.9 +/- 4.8 in the MVG group (P = 0.0042).
Conclusions: Ablation for atrial flutter using an MVG technique results in significantly less ablation requirements than the traditional approach, potentially by concentrating ablation lesions on the muscle bundles responsible for transisthmus conduction.