178 Catheter inversion during cavotricuspid isthmus catheter ablation: the new shaft visualization catheter reduces fluoroscopy use

Aims Catheter ablation (CA) is the choice therapy of cavotricuspid isthmus (CTI) atrial flutter. The aim of this study was to describe our approach to improve the CTI ablation using a zero-fluoroscopy (ZF). The procedural difficulties could be related to anatomical characteristics of the CTI. Methods and results One hundred eighty-eight patients that performed CA of CTI were retrospectively and consecutively evaluated between 2017 and 2019. The studied population was divided into two groups. Eighty-eight patients who were undergone CA using ablation catheter without shaft visualization catheter (NSV) were Group 1. One hundred patients were undergone CA using ablation catheter with a shaft visualization (SV); they were Group 2. The catheter was looped at the Eustachian ridge after 200 s of radiofrequencies (RF) without elimination of local electrogram. A conduction line block of CTI was obtained in all patients of Group 2 using a ZF approach. In 16 patients of Group 1, the catheter inversion was obtained using fluoroscopy to avoid damages during its loop. In Group 2, a complete CTI block was obtained with a catheter inversion approach in 10 patients without fluoroscopy, visualizing the shaft and the tip of the ablation catheter on the electroanatomic (EAM) map. In the overall population studied the use of SV had a linear correlation with the ZF approach (r = 0.629; P < 0.001). The duration of RF was lower in Group 2 than in Group 1 (Group 1: 27.8 ± 6.3 vs. Group 2: 15.6 ± 7.2 min; P < 0.01). The procedure time between two groups was lower in Group 2 than in Group 1 (Group 1: 58.4 ± 22.4 vs. Group 2: 42.2 ± 15.7 min; P < 0.01). No differences between two groups were documented regarding success and complications. Conclusions The visualization of the shaft’s catheter on the EAM permitted the catheter inversion safely in order to overcome some complex CTI anatomy and obtain bidirectional block. The SV reduced procedure time, RF applications, and fluoroscopy exposition during CTI ablation.

Risk of New-Onset Atrial Fibrillation Post-cavotricuspid Isthmus Ablation in Typical Atrial Flutter Without History of Atrial Fibrillation

Aims: The aim was to describe the incidence of atrial fibrillation (AF) after cavotricuspid isthmus (CTI) ablation in patients with typical atrial flutter (AFL) without history of AF and to identify risk factors for new-onset AF after the procedure.Methods: A total of 191 patients with typical AFL undergoing successful CTI ablation were enrolled. Patients who had history of AF, structural heart disease, cardiac surgery, or ablation or who received antiarrhythmic drug after procedure were excluded. Clinical and electrophysiological data were collected.Results: There were 47 patients (24.6%) developing new AF during a follow-up of 3.3 ± 1.9 years after CTI ablation. Receiver operating characteristic (ROC) curves indicated that the cut-off values of left atrial diameter (LAD) and CHA2DS2-VASc score were 42 mm and 2, with area under the curve of 0.781 and 0.550, respectively. The multivariable Cox regression analysis revealed that obstructive sleep apnea (OSA) [hazard ratio (HR) 3.734, 95% confidence interval (CI) 1.470–9.484, P = 0.006], advanced interatrial block (aIAB) (HR 2.034, 95% CI 1.017–4.067, P = 0.045), LAD > 42 mm (HR 2.710, 95% CI 1.478–4.969, P = 0.001), and CHA2DS2-VASc score > 2 (HR 2.123, 95% CI 1.118–4.034, P = 0.021) were independent risk factors of new-onset AF.Conclusion: A combination of OSA, aIAB, LAD > 42 mm, and CHA2DS2-VASc > 2 was a strongly high risk for new-onset AF after ablation for typical AFL, and it had significance in postablation management in clinical practice.

Impact of cavotricuspid isthmus depth on the ablation index for successful first-pass typical atrial flutter ablation

Cavotricuspid isthmus (CTI) linear ablation has been established as the treatment for typical atrial flutter. Recently, ablation index (AI) has emerged as a novel marker for estimating ablation lesions. We investigated the relationship between CTI depth and ablation parameters on the procedural results of typical atrial flutter ablation. A total of 107 patients who underwent CTI ablation were retrospectively enrolled in this study. All patients underwent computed tomography before catheter ablation. From the receiver-operating curve, the best cut-off value of CTI depth was < 4.1 mm to predict first-pass success. Although the average AI was not different between deep CTI (DC; CTI depth ≥ 4.1) and shallow CTI (SC; CTI depth < 4.1), DC required a longer ablation time and showed a lower first-pass success rate (p < 0.01). In addition, the catheter inversion technique was more frequently required in the DC (p < 0.01). The lowest AI sites of the first-pass CTI line were determined in both the ventricular (2/3 segment of CTI) and inferior vena cava (IVC, 1/3 segment of CTI) sides. The best cut-off values of the weakest AIs at the ventricular and IVC sides for predicting first-pass success were > 420 and > 386, respectively. Among patients with these cut-off values, the first-pass success rate was 89% in the SC and 50% in the DC (p < 0.01). Although ablation parameters were not significantly different, the first-pass success rate was lower in the DC than in the SC. Further investigation might be required for better outcomes in deep CTIs.

Anatomical variants of the cavotricuspid isthmus in patients undergoing catheter ablation for atrial flutter and/or atrial fibrillation

Background We evaluated the differences in the anatomy of the cavotricuspid isthmus (CTI) by assessing image loops provided by intracardiac echocardiography (ICE) in patients who underwent ablation for atrial flutter and/or atrial fibrillation. Purpose CTI is an essential component of the reentrant circle in isthmus–dependent atrial flutter (CTI-AFL) and a target for catheter ablation. In some patients, CTI anatomy may be responsible for a difficult procedure. The aim of this study is to describe in details the anatomical variants of this structure. Methods We included a group of 138 patients, who underwent cardiac ablation for atrial flutter and/or atrial fibrillation between August 2020 and January 2021. Intracardiac echocardiography was employed during the intervention to evaluate the morphology of CTI. Analysis was focused on size, shape, presence of sub-eustachian pouch (excavation more than 5 mm) or presence of prominent Eustachian ridge (ER, embryologic remnant of the valve of the IVC) and mobility of the structure. Results The length of CTI measured during ventricular systole averaged at 38,4mm (min 22,5mm, max 60mm). The most frequent pattern was a flat CTI without sub-eustachian excavation or with excavation less than 5mm (71 patients; 51.4%). A pouch (excavation more than 5mm) was observed in 41 pts (29.7%), where the deepest pouch reached 10,5mm. Prominent ER was present in 58 pts (42%). The remaining 26 of CTIs (18.8%) were classified in the “unclassifiable” category with deviations from common anatomic variants - substantial convexity, pronounced trabeculation of isthmus or double pouch. We observed 14 CTIs (10.1%), where the structure was partially or in full extent detached from the diaphragm, sliding during cardiac contractions. In addition to the described morphology, Chiari's network was observed in 18 pts (13%). In reference to mobility, 53 pts (38.4%) presented with hypermobile CTI with a difference in size of more than 1/3 between the diastole and systole. Moreover, we looked into differences of CTI related to BMI, left atrial volume index (LAVi) and ejection fraction of the left ventricle. A positive correlation was found between LVEF and mobility of CTI. Hypermobile CTI was present in 42.2% of pts with normal LVEF compared to only 18.9% of pts with reduced EF (EF less than 50%). Similar results were observed in pts with non-dilated LA, where hypermobile CTI was present in 51.9% of pts compared to only 35.1% of pts with dilated LA with LAVi &gt;28 ml/m2 (see table below). Conclusions We observed a substantial differences in the anatomy of the CTI, which could play an important role in catheter ablation of this structure. Besides the prominent ER, significant sub-eustachian pouch and hypermobility appear to be variants predisposing to difficult ablation. FUNDunding Acknowledgement Type of funding sources: None. CTI variants related to EFLV, BMI, LAVi CTI detached from the diaphragm

Prospective Evaluation of a Standardized Screening for Atrial Fibrillation after Ablation of Cavotricuspid Isthmus Dependent Atrial Flutter

Aims: We aimed to prospectively investigate the effectiveness of a standardized follow-up for AF-detection after common atrial flutter (cAFL) ablation. Methods: A total of 309 patients after cAFL ablation without known AF, from 5 centers, and at least one completed, standardized follow-up at 3, 6 and 12 months, including a 24 h Holter-electrocardiogram (ECG), were included. The primary outcome was incident atrial fibrillation (AF), or atrial tachycardia (AT). Predictors were investigated by Cox proportional-hazards models. Results: The mean age was 67.9 years; 15.2% were female and the mean CHA2DS2-VASc (Congestive heart failure, Hypertension, Age, Diabetes, Stroke, Vascular disease, Sex category) score was 2.4 points. The great majority of patients (90.3%) were anticoagulated. Over a mean follow-up of 12.2 months with a standardized approach, AF/AT was detected in 73 patients, corresponding to 11.7% at 3 months, 18.4% at 6 months and 28.2% at 12 months of follow-up. AF was found in 64 patients, AT in 9 and both in 2 patients. Occurrence of AF was recorded in 40 (60.6%) patients by Holter-ECG and in the remaining 26 (39.4%) by clinical follow-up only. There was no difference in male versus female (p = 0.08), or in younger versus older patients (p = 0.96) for AF/AT detection. Only coronary artery disease (hazard ratio [95% confidence intervals] 1.03 [1.01–1.05], p = 0.01) was associated with the primary outcome. Conclusions: AF or AT was detected in a large proportion of cAFL patients after cavotricuspid-isthmus (CTI) ablation, using a standardized follow-up over 1 year. This standardized screening can be easily implemented with high patient acceptance. The high proportion of post-ablation AF needs to be taken into consideration when deciding on long-term oral anticoagulation.