Outcomes of cavotricuspid isthmus-dependent fLutter ablation: randomized study comparing single vs multiple catheter procedures. The SIMPLE study

FUNDING ACKNOWLEDGEMENTS: Type of funding sources: None. BACKGROUND: Catheter ablation is recommended as first-line therapy for patients with symptomatic typical atrial flutter (AFl). Although the conventional multi-catheter approach is the standard of care for cavotricuspid isthmus (CTI) ablation, a single-catheter approach was recently described as a feasible alternative. PURPOSE: The present study sought to compare safety, efficacy, and efficiency of single vs multi-catheter approach for AFl ablation. METHODS: In this randomized multicentre study, consecutive patients referred for AFl ablation (n= 253) were enrolled and randomized to multiple vs single-catheter approach for CTI ablation. In the single-catheter arm CTI block was confirmed analyzing PR interval (PRI) on the surface ECG as previously described by Madaffari and colleagues: briefly, PRI defined as the time between the pacing spike and the onset of the QRS complex, was measured on the surface ECG during atrial pacing (10 V, 1.5 ms) at a stable cycle length from the tip of the ablation catheter placed at 5 o’clock (medial to CTI line), 7 o’clock (lateral to CTI line), and 9 o’clock position. CTI block was assumed when: (i) the PRI at 7 o’clock was >80ms longer than that at pacing sites of 5, and (ii) the PRI at 9 o’clock was shorter than the PRI at 7 o’clock (Figure 1). Procedural and follow-up data were collected and compared between the two arms. RESULTS: 128 and 125 patients were assigned to the single-catheter and to the multi-catheter arms, respectively. In the single-catheter arm, procedure time was singificantly shorter (37±25 vs 48±27 minutes, p=0.002), required less fluoroscopy time (430±461 vs 712±628 seconds, p<0.001) and less radiofrequency time (428±316 vs 643±519 seconds, p<0.001), achieving a higher first-pass CTI block rate [55 (45%) vs 37 (31%), p=0.044], compared with the multi-catheter arm. After a median follow-up of 12 months, 11 (4%) patients experienced AFl recurrences [5 (4%) in the single-catheter arm and 6 (5%) in the multi-catheter arm, P=0.99]. No differences were found in arrhythmia-free survival between arms (log-rank= 0.71). Results are summarized in Figure 2. CONCLUSIONS: Recurrence-free survival of the single-catheter approach for typical AFl ablation is not inferior to the conventional multiple-catheter approach, reducing procedure, fluoroscopy and radiofrequency time. [Figure: see text] [Figure: see text]