Feasibility of mitral isthmus and left atrial roof linear lesions using an 8 mm tip cryoablation catheter

Catheter ablation of atrial fibrillation in Korea: results from the Korean Heart Rhythm Society Ablation Registry for Atrial Fibrillation (KARA)

Background

This study aims to investigate the current status of AF (atrial fibrillation) catheter ablation in Korea.

Methods

The patients who underwent AF catheter ablation from September 2017 to December 2019 were prospectively enrolled from 37 arrhythmia centers. Demographic data, procedural characteristics, the extent of catheter ablation, acute success of the ablation lesion set, rate and independent risk factor for recurrence of AF were analyzed.

Results

A total of 2402 AF patients [paroxysmal AF (PAF) 45.7%, persistent AF (PeAF) 43.1% and redo AF 11.2%] were included. Pulmonary vein isolation (PVI) was performed in 2378 patients (99%) and acute success rate was 97.9%. Additional non-PV ablation (NPVA) were performed in 1648 patients (68.6%). Post-procedural complication rate was 2.2%. One-year AF-free survival rate was 78.6% and the PeAF patients showed poorer survival rate than the ones with other types (PeAF 72.4%, PAF 84.2%, redo AF 80.0%). Additional NPVA did not influence the recurrence of AF in the PAF patients (PVI 17.0% vs. NPVA 14.6%, P value 0.302). However, it showed lower AF recurrence rate in the PeAF patients (PVI 34.9% vs. NPVA 24.4%, P value 0.001). Valvular heart disease, left atrial diameter, PeAF, PVI alone, need of NPVA for terminating AF, and failed ablation were independent predictors of AF recurrence.

Conclusions

Additional NPVA was associated better rhythm outcome in the patients with PeAF, not in the ones with PAF. The independent risk factors for AF recurrence in Korean population were similar to previous studies. Further research is needed to discover optimal AF ablation strategy.

Cryothermal atrial linear ablation in patients with atrial fibrillation: An insight from the comparison with radiofrequency atrial linear ablation

BACKGROUND

Atrial linear lesions are generally created with radiofrequency energy. We sought to evaluate the feasibility of cryothermal atrial linear ablation.

METHODS AND RESULTS

Twenty-one atrial fibrillation (AF) patients underwent linear ablation on the left atrial (LA) roof, mitral isthmus (MI), and cavotricuspid isthmus (CTI) with 8-mm-tip cryocatheters following pulmonary vein isolation. The data were compared with those of 31 patients undergoing linear ablation with irrigated-tip radiofrequency catheters. Conduction block was successfully created in 18 of 20 (90%), 9 of 21 (43%), and 20 of 20 (100%) on the LA roof, MI, and CTI by endocardial cryoablation alone with 19.0 (12.0-24.0), 30.0 (23.0-34.0), and 14.0 (14.0-16.0) minute cryo applications, respectively. The presence of either an interposed circumflex artery or pouch at the MI was significantly associated with failed MI block (P = .04). Conduction block was created in 25 of 31 (83.9%), 27 of 31 (87.1%), and 30 of 31 (96.8%) on the roof, MI, and CTI, respectively, by radiofrequency ablation. During the 17.5 (13.0-31.7) months of follow-up, freedom from AF/atrial tachycardia (AT) was significantly higher in the cryo group (P = .05); especially, recurrent AT was more frequent in the RF group (8/31 vs 1/21; P = .03). Conduction block across the roof, MI, and CTI was durable in 6 of 12 (50.0%), 4 of 12 (33.3%), and 9 of 12 (75.0%) patients during second procedures. All nine patients (except one) with recurrent ATs had at least one roof or MI conduction resumption.

CONCLUSIONS

Cryoablation is effective for creating a roof and CTI linear block, however, creating MI block by endocardial ablation alone was often challenging. Conduction resumption of LA linear block is common and recurrent arrhythmias, especially iatrogenic ATs, are more frequently observed after radiofrequency linear ablation.

Visualization of catheter ablation for atrial fibrillation: Impact of devices and anatomy

Endocardial access to the left atrium is commonly achieved to treat patients with atrial fibrillation, using different device delivery systems for cardiac ablation. But the large variation in human anatomy presses the limits of existing medical devices. In this unique study, we directly visualized the device-tissue interface in fresh reanimated human hearts using Visible Heart^® methodologies. Our goal was to better understand any opportunities to improve therapeutic approaches. The visual images obtained in this study (also featured in this article) allow a more intimate grasp of the key steps required in various ablation procedures, as well as some limitations of current device designs. These images show the potential risks of conducting transseptal punctures and the difficulties of placing catheter tips in certain scenarios (e.g., when creating circumferential lesions); they also demonstrate potential problems that could occur while attempting to place catheter tips on such anatomies like the mitral isthmus. In our analysis of these images, we focus on where enhancements are needed to refine device functionality.

Pouched mitral isthmus is associated with incomplete linear block in atrial fibrillation patients with mechanical mitral valve replacement

BACKGROUND

Previous studies have described the impact of mitral isthmus (MI) anatomy on the likelihood of achieving MI linear block in patients with native mitral valves (NMV) who underwent atrial fibrillation (AF) ablation. However, none have investigated that issue in AF patients with mechanical mitral valve replacements (MMVR).

METHODS AND RESULTS

Twenty-nine consecutive patients who developed symptomatic persistent AF post-MMVR and referred for ablation were enrolled. Twenty-nine patients with NMV who underwent ablation of persistent AF during the same period were matched. With preprocedural cardiac computed tomographic imaging, MI anatomical features of all the participants were analyzed. Pouched MI was observed in 19 (65.5%) MMVR patients versus to 6 (20.7%) controls (P = 0.001). Bidirectional linear block across MI was achieved in 21 (72.4%) MMVR patients and 22 (75.9%) in the controls (P = 0.764). In the multivariable analysis, pouched MI was an independent predictor of incomplete MI block.

CONCLUSIONS

Pouched MI accounts for the majority of AF patients with MMVR and may be associated with incomplete bidirectional linear block of MI.

Is cryoballoon ablation preferable to radiofrequency ablation for treatment of atrial fibrillation by pulmonary vein isolation? A meta-analysis

OBJECTIVE

Currently radiofrequency and cryoballoon ablations are the two standard ablation systems used for catheter ablation of atrial fibrillation; however, there is no universal consensus on which ablation is the optimal choice. We therefore sought to undertake a meta-analysis with special emphases on comparing the efficacy and safety between cryoballoon and radiofrequency ablations by synthesizing published clinical trials.

METHODS AND RESULTS

Articles were identified by searching the MEDLINE and EMBASE databases before September 2013, by reviewing the bibliographies of eligible reports, and by consulting with experts in this field. Data were extracted independently and in duplicate. There were respectively 469 and 635 patients referred for cryoballoon and radiofrequency ablations from 14 qualified clinical trials. Overall analyses indicated that cryoballoon ablation significantly reduced fluoroscopic time and total procedure time by a weighted mean of 14.13 (95% confidence interval [95% CI]: 2.82 to 25.45; P = 0.014) minutes and 29.65 (95% CI: 8.54 to 50.77; P = 0.006) minutes compared with radiofrequency ablation, respectively, whereas ablation time in cryoballoon ablation was nonsignificantly elongated by a weighted mean of 11.66 (95% CI: -10.71 to 34.04; P = 0.307) minutes. Patients referred for cryoballoon ablation had a high yet nonsignificant success rate of catheter ablation compared with cryoballoon ablation (odds ratio; 95% CI; P: 1.34; 0.53 to 3.36; 0.538), and cryoballoon ablation was also found to be associated with the relatively low risk of having recurrent atrial fibrillation (0.75; 0.3 to 1.88; 0.538) and major complications (0.46; 0.11 to 1.83; 0.269). There was strong evidence of heterogeneity and low probability of publication bias.

CONCLUSION

Our findings demonstrate greater improvement in fluoroscopic time and total procedure duration for atrial fibrillation patients referred for cryoballoon ablation than those for radiofrequency ablation.