Ablation index-guided high-power vs. moderate-power cavotricuspid isthmus ablation

Ablation index (AI)-guided ablation is useful for pulmonary vein isolation (PVI) and cavotricuspid isthmus (CTI) ablation. However, the impact of radiofrequency (RF) application power on CTI ablation with a fixed target AI remains unclear. One-hundred-thirty drug-refractory atrial fibrillation and/or atrial flutter patients who underwent AI-guided CTI ablation with or without PVI between July 2020 and August 2021 were randomly assigned to high-power (45 W) and moderate-power (35 W) groups. We performed CTI ablation with the same target AI value in both groups: 500 for the anterior 1/3 segments and 450 for the posterior 2/3 segments. In total, first-pass conduction block of the CTI was obtained in 111 patients (85.4%), with 7 patients (5.4%) showing CTI reconnection. The rate of first-pass conduction block was significantly higher in the 45 W group (61/65, 93.8%) than in the 35 W group (50/65, 76.9%, P = 0.01). CTI ablation and CTI fluoroscopy time were significantly shorter in the 45 W group than in the 35 W group (CTI ablation time: 192.3 ± 84.8 vs. 319.8 ± 171.4 s, P < 0.0001; CTI fluoroscopy time: 125.2 ± 122.4 vs. 171.2 ± 124.0 s, P = 0.039). Although there was no significant difference, steam pops were identified in two patients from the 45 W group at the anterior segment of the CTI. The 45 W ablation strategy was faster and provided a higher probability of first-pass conduction block than the 35 W ablation strategy for CTI ablation with a fixed AI target.

Effectiveness and safety of high-power and short-duration ablation for cavotricuspid isthmus ablation in atrial flutter

BACKGROUND

Despite many studies on new tools and strategies for cavotricuspid isthmus (CTI) ablation, there is an unmet need to improve the CTI ablation procedure. Recently, high-power short-duration (HPSD) ablation has been widely used for pulmonary vein (PV) isolation in atrial fibrillation. We evaluated the effectiveness and safety of HPSD for CTI ablation in atrial flutter (AFL).

METHODS

Eighty-four patients who underwent CTI ablation with or without simultaneous PV isolation between January 2018 and February 2019 were enrolled in this prospective cohort study. We compared procedural characteristics, periprocedural complications, and recurrence of atrial tachyarrhythmia (ATa) between the HPSD group (50 W for 15 s) and conventional group (30 W for 60 s).

RESULTS

A total of 84 patients were divided into the HPSD (n = 42) and conventional (n = 42) groups. Bidirectional CTI block was achieved in all patients and 95% achieved bidirectional block after the first-line ablation in both groups. Although there was no difference in the total number of ablation lines between the two groups (1.17 ± 0.7 vs 1.38 ± 0.8, P = .067), HPSD ablation significantly reduced total ablation time compared to the conventional group (236.0 ± 85.6 vs 534.2 ± 235.2 s, P < .001). One pericardial tamponade was reported in the HPSD group. During the mean follow-up of 9.3 ± 4.8 months, CTI-dependent AFL recurrence occurred in one patient in the HPSD group. Recurrence of ATa developed in 14 patients with no significant difference between the groups.

CONCLUSION

Our study demonstrates that HPSD CTI ablation is safe and can shorten procedure time.

A comparison of 8-mm and open-irrigated gold-tip catheters for typical atrial flutter ablation: Data from a prospective multicenter registry

BACKGROUND

Cavotricuspid isthmus (CTI) radiofrequency (RF) catheter ablation is the standard treatment for patients suffering from CTI-dependent atrial flutter (AFL). The aim of this study was to compare the use in clinical practice of 8-mm gold-tip catheter (8mmRFC) and open-irrigated gold-tip catheter (irrRFC) for RF typical AFL ablation.

METHODS

Patients with typical AFL were treated with 8mmRFC or irrRFC catheters according to investigator preferences. The primary endpoint was the cumulative radiofrequency time (CRFT). Fluoroscopy time, acute and 6-month success rates were secondary endpoints.

RESULTS

After excluding 3 patients with left AFL, 157 of the enrolled patients (median age 71.8 [interquartile range, 64.1-76.2], 76% men, 91% in NYHA class ≤II, 65% with no structural heart disease) were analyzed: 74 (47%) subjects were treated with the 8mmRFC and 83 (53%) with the irrRFC. The median CRFT was 3 [2-6] minutes in the 8mmRFC group and 5 [3-7] minutes in the irrRFC group (P = .183). There were no significant differences in ablation success rates, intraprocedural CTI reconnections, audible steam pops, and procedural times. In the 8mmRFC group, a significantly lower fluoroscopy time was observed as compared to the irrRFC group (8 [5-12] vs 15 [10-20] minutes, P < .001). During the follow-up period, AFL recurrences were documented in 3 patients in the 8mmRFC group and 2 in the irrRFC group (P = .655).

CONCLUSIONS

The 8mmRFC and the irrRFC performed similarly in routine practice for CTI ablation in terms of cumulative RF time, acute and 6-month success rates. Fluoroscopy time was significantly lower in the 8mmRFC group.

First clinical experience of a dedicated irrigated-tip radiofrequency ablation catheter for the ablation of cavotricuspid isthmus-dependent atrial flutter

BACKGROUND

Different types of irrigated-tip ablation catheters are available for ablation of atrial flutter (AFL). The aim of this study was to compare an established with a novel dedicated Gold irrigated-tip catheter for ablation of AFL.

METHODS AND RESULTS

We compared consecutive patients undergoing ablation of AFL using a standard 3.5 mm irrigated-tip platinum-iridium (Pt-Ir) catheter (Thermocool, TC-group) and a 3.5 mm irrigated gold-tip catheter (Gold-group) specifically designed for cavotricuspid isthmus ablation (CTI). The primary endpoint was acute efficacy (net RF time) to achieve block across the CTI. Secondary endpoints included procedure time, fluoroscopy duration, complications, and recurrence of AFL.153 patients (age 68 ± 11 years, 74% male) were included. Net RF time to achieve CTI block was not different between the TC-group (793 ± 503 s) and the Gold-group (706 ± 422 s; p = 0.406). Total procedure time was not significantly different between the TC-group (70 ± 26 min) and the Gold-group (70 ± 27 min; p = 0.769). A significant difference between the groups was identified for the fluoroscopy duration (TC-group: 934 ± 537 s, Gold-group: 596 ± 362 s, p < 0.001). There were no major complications observed in the groups. Recurrence of AFL occurred in 3 of 66 (5%) in the TC-group and in 2 of 87 (2%) in the Gold-group (p = 0.652).

CONCLUSIONS

In conclusion, acute and chronic efficacy of the irrigated Pt-Ir and gold-tip catheters were comparable. However, the dedicated catheter design was associated with decreased fluoroscopy duration.

Prospective evaluation of a novel catheter equipped with mini electrodes on a 10-mm tip for cavotricuspid isthmus ablation - The efficacy of a mini electrode guided ablation

BACKGROUND

Clinical utility of large-tip ablation catheters for cavo-tricuspid isthmus (CTI) ablation has been reported, however, it is limited by the impaired near-field electrogram resolution. This study evaluated the efficiency of a novel mini-electrode (ME) equipped 10-mm tip CTI ablation catheter.

METHODS

Thirty-four patients were prospectively enrolled (Group-A). Initially, radiofrequency energy was applied point-by-point guided by ME signals. If it failed, RF applications were applied conventionally guided by tip-ring signals. The data were compared with 32 and 32 patients undergoing CTI ablation using 8-mm tip (Group-B) and 3.5-mm irrigation-tip (Group-C) catheters, respectively.

RESULTS

The successful CTI block creation rate was significantly higher in Group-A and Group-B than Group-C (32/34[94.1%], 31/32[96.8%], and 25/32[78.1%], p=0.027). In Group-A, ME guided ablation was successful in 30 patients and subsequent conventional ablation in 2. There was no significant difference between the 3 groups for the total procedure and fluoroscopic times using the initial catheters. However, the total radiofrequency applications (6.9±3.6, 9.9±4.3, and 12.0±7.1, p=0.001), total radiofrequency time (358±197, 558±248, and 566±265s, p=0.001), and radiofrequency time to achieve initial block (222±159, 471±242, and 396±211s, p<0.001) were significantly shorter in Group-A than Group-B and Group-C. In Group-A, a maximal ME amplitude attenuation (86±13%, from 0.84±0.53 to 0.08±0.04mV) was obtained by 19.0±6.5s mean applications. Maximal tip-ring amplitude attenuation (76±17%, from 0.58±0.29 to 0.12±0.09mV) was obtained by 22.1±6.2s mean applications.

CONCLUSIONS

ME guided ablation using a novel ME equipped 10-mm tip ablation catheter was feasible for human CTI ablation, and might reduce inadvertent radiofrequency applications.

Novel strategies in the ablation of typical atrial flutter: role of intracardiac echocardiography

Radiofrequency ablation (RFA) of the cavo-tricuspid isthmus (CTI) is one of the most frequently performed procedures in electrophysiology. Despite a high success rate, ablation of the CTI can be unusually difficult in some cases. Multiple tools like angiography, 3D mapping, remote navigation and intracardiac echocardiography (ICE) have been introduced to facilitate typical flutter ablation. This review article summarizes the clinical value of different strategies and tools used for CTI ablation focusing on the importance of approaches utilizing ICE.

Catheter ablation for supraventricular tachycardias: contemporary issues

The treatment of cardiac arrhythmias has evolved significantly over the last 30 years. Understanding of arrhythmia mechanisms has led to pharmacologic therapies, surgical interventions and the widely used percutaneous catheter ablation techniques. The focus of this review is centered on the current catheter ablation therapies available for supraventricular tachycardia. We will discuss current management strategies including challenges when considering catheter ablation therapy for management of supraventricular tachycardias: atrioventricular nodal reentrant tachycardia, atrioventricular reentrant tachycardia utilizing an accessory pathway, atrial tachycardia and atrial flutter. Selected contemporary issues related to supraventricular tachycardia physiology, ablation approaches and ablation outcomes and complications will be discussed. Future goals for electrophysiologists are to continue to improve procedural safety and efficiency, while maintaining the impressive success rates that have been achieved.

Impact of respiration on electroanatomical mapping of the right atrium: implication for cavotricuspid isthmus ablation

PURPOSE

Cavotricuspid isthmus (CTI) ablation for typical atrial flutter (AFL) has become the preferred treatment for this arrhythmia. The aims of this study were to assess the impact of respiratory gating (RG) on electroanatomical mapping of CTI and to assess the efficiency of CTI ablation guided by the Carto3® system equipped with the new respiration gating software.

METHODS

Forty-four consecutive patients (mean age, 60 ± 13 years; 25 male) undergoing cavotricuspid ablation for symptomatic common AFL were randomly assigned to CARTO™ mapping with or without enabling RG module (Group A, RG OFF, Group B, RG ON).

RESULTS

A significant reduction in mean RA volume, CTI central length and CS ostium maximum diameter has been observed in the RG maps. The mean total procedural, fluoroscopy and radiofrequency (RF) time were 102.9 ± 35.3, 10.6 ± 3.3, 22.9 ± 14.2 min in group A and 75.3 ± 21.7, 3.6 ± 4.5, 10.4 ± 5.7 min in group B, respectively (p < 0.05).

CONCLUSIONS

Electroanatomical mapping systems' accuracy may be strongly influenced by respiration movements. The current study showed that automatic respiratory gated acquisition resulted in a better visualization of CTI, and this determines a relevant reduction in fluoroscopy and RF times.

Biophysics and clinical utility of irrigated-tip radiofrequency catheter ablation

Catheter ablation by radiofrequency (RF) energy has successfully eliminated cardiac tachyarrhythmias. RF ablation lesions are created by thermal energy. Electrode catheters with 4-mm-tips have been adequate to ablate arrhythmias located near the endocardium; however, the 4-mm-tip electrode does not readily ablate deeper tachyarrhythmia substrate. With 8- and 10-mm-tip RF electrodes, ablation lesions were larger; yet, these catheters are associated with increased risk for coagulum, char and thrombus formation, as well as myocardial steam rupture. Cooled-tip catheter technology was designed to cool the electrode tip, prevent excessive temperatures at the electrode tip-tissue interface, and thus allow continued delivery of RF current into the surrounding tissue. This ablation system creates larger and deeper ablation lesions and minimizes steam pops and thrombus formation. The purpose of this article is to review cooled-tip RF ablation biophysics and outcomes of clinical studies as well as to discuss future technological improvements.