Long-term outcomeS of cavotrIcuspid isthMus-dePendent fLuttEr Ablation: Single vs Double Catheter Procedure

Long-term outcomeS of cavotrIcuspid isthMus-dePendent fLuttEr Ablation: Single vs Double Catheter Procedure

Long-term outcomeS of cavotrIcuspid isthMus-dePendent fLuttEr Ablation: Randomized Study Comparing Single vs Double Catheter Procedure

Catheter ablation is recommended as first-line therapy for most patients with typical atrial flutter. The most common approach is to create an ablation line across the cavotricuspid isthmus (CTI). Traditionally, atrial flutter ablation has been performed with a conventional approach using two catheters, an ablation catheter and a duodecapolar catheter that is placed at the level of the tricuspid annulus to confirm the CTI block. Recently, a single catheter approach has been described using the behavior of PR interval change during differential pacing over the ablation line to prove CTI block. This prospective, randomized, multicenter study analyzes the effectivity of a single catheter approach compared with conventional approach in terms of clinical outcomes.

Typical atrial flutter is a reentrant rhythm in the right atrium that is constrained anteriorly by the tricuspid annulus and posteriorly by the crista terminalis and eustachian ridge. Catheter ablation is the first-line therapy for most patients with typical atrial flutter. The most common approach is to create an ablation line across the CTI, from the tricuspid annulus to the inferior vena cava. Traditionally, atrial flutter ablation has been performed with a conventional approach using two catheters, an ablation catheter and a duodecapolar catheter that is placed at the level of the tricuspid annulus that allows to evaluate the right atrial activation sequence to confirm the CTI block. Recently, a single catheter approach has been described using the behavior of PR interval (PRI) change during differential pacing over the ablation line to prove CTI block. The PRIs is measured for three different pacing site, 5 o'clock (medial to CTI line), 7 o'clock (lateral to CTI line), and 9 o'clock position. CTI block was assumed when the PRI at 7 o'clock was >80ms longer than that at pacing sites of 5 o'clock and the PRI at 9 o'clock was shorter than the PRI at 7 o'clock. However, a direct comparison between this approach and the conventional one was not yet performed. This prospective, randomized, multicenter study analyzes the effectivity of a single catheter approach compared with conventional approach in terms of clinical outcomes. Our research hypothesis is that a single catheter approach has the possible advantages of being a faster, more efficient and cheaper procedure than the conventional approach. Moreover, as it only requires a single venous access, the risk of complications is decreased.

Double venous femoral access will be obtained. A duodecapolar catheter placed around tricuspid annulus will be used to prove isthmus block after CTI ablation.

Ablation will be performed similar as described in the Group A. After the ablation line is over, PRI on the surface ECG will be used to prove isthmus block after CTI ablation.

Single venous femoral access will be obtained and the ablation will be performed similar to Group A. After the ablation line is over, we will confirm CTI block using the PRI. During atrial pacing (10 V, 1.5 ms) at a stable cycle length (range 500-700ms) from the tip of the ablation catheter with a sweep speed of 300mm/s, the ablation catheter will be placed first at 5 o'clock (medial to CTI line), then at 7 o'clock (lateral to CTI line), and finally at 9 o'clock position, and the corresponding PRIs will be measured for each pacing site. CTI block is assumed when: (i) the PRI at 7 o'clock is >80ms longer than that at pacing sites of 5, and (ii) the PRI at 9 o'clock is shorter than the PRI at 7 o'clock.

Double venous femoral access will be obtained. A duodecapolar catheter will be positioned in the right atrium around the tricuspid valve annulus (TVA) to record activation sequence around the tricuspid annulus. An ablation catheter will be positioned using fluoroscopic guidance in the central CTI, 6 o'clock in a left anterior oblique view. The distal ablation electrode position will then be adjusted toward or away from the TVA, based on the ratio of atrial and ventricular electrogram amplitudes with an optimal ratio of 1:2 or 1:4 at the TVA. After the ablation catheter is positioned, it will be very slowly withdrawn during ablation toward the inferior vena cava while radiofrequency energy is applied continuously. CTI block will be evaluated after ablation by determining the right atrial activation sequence during pacing from the low lateral right atrium and coronary sinus ostium.

The recurrence rate of typical atrial flutter at 6 months post cavotricuspid isthmus ablation will be evaluated in both groups to determine if the single catheter approach is non-inferior when compared to traditional approach using two catheters.

The total procedure time time will be measured in both groups to determine if the single catheter approach is more efficient procedure.

The ablation time will be measured in both groups to determine if the single catheter approach is more efficient procedure.

The fluoroscopy time will be measured in both groups to determine if the single catheter approach is more efficient procedure.

Inclusion Criteria: Patients admitted at any of the centers to perform a CTI ablation. Signed informed consent Exclusion Criteria: Age < 18 years. Pregnancy. Impossibility to perform CTI ablation. Impossibility to measure PRI (complete atrioventricular block). Ablation of other cardiac arrhythmias during the same procedure. Medical, geographical and social factors that make study participation impractical, and inability to give written informed consent. Patient's refusal to participate in the study.

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