Preventing atrial fibrillation by combined right isthmus ablation and cryoballoon pulmonary vein isolation in patients with typical atrial flutter: PAF-CRIOBLAF study

Evaluation of risk factors for long-term atrial fibrillation development in patients undergoing typical atrial flutter ablation: a multicenter pilot study

BACKGROUND

Atrial flutter (AFL) and atrial fibrillation (AF) are the most commonly detected supraventricular arrhythmias and share similar pathophysiological mechanisms. After the successful ablation of AFL, AF frequently occurs in the long-term follow-up. As emphasized in some studies, certain mechanisms seem to predispose to the development of AF in AFL patients, and approximately 20% of these patients have accompanying AFL.

PURPOSE

We aimed to analyze independent risk factors that predict the development of AF in patients who underwent typical AFL ablation.

METHODS

This was a multicenter, cross-sectional, and retrospective study. A total of 442 patients who underwent typical AFL ablation at three different centers between January 1, 2018 and January 1, 2022 were included retrospectively. After the ablation procedure the patients were divided into those who developed AF and those who did not. The patients were followed up for an average of 12 (4-20) months. In the post-procedural period, atrial arrhythmias were investigated with 24‑h Holter and ECG at 1 month, 6 months, and 12 months and then at 6‑month intervals thereafter.

RESULTS

Overall, AF developed in 206 (46.6%) patients in the long-term follow-up. Age, hypertension (HT), obstructive sleep apnea syndrome (OSAS), previous cerebrovascular accident (CVA), left atrium anteroposterior diameter, severe mitral regurgitation, hemoglobin, blood glucose, and HbA1c values were found to be significant in univariable analysis. According to multivariable analysis, HT (p = 0.014; HR: 1.483 [1.084-2.030]), OSAS (p = 0.008; HR: 1.520 [1.117-2.068]) and previous CVA (p = 0.038; HR: 1.749 [1.031-2.968]) were independently associated with the development of AF in AFL patients who underwent ablation procedure.

CONCLUSION

In the present study, we found that HT, OSAS, and previous CVA were independently correlated with the development of AF in the long-term follow-up of patients who underwent typical AFL ablation. We consider that AFL patients with such risk factors should be followed up closely following cavotricuspid isthmus ablation for the development of AF.

Impact of pulmonary vein isolation on atrial arrhythmias in patients with typical atrial flutter: systematic review and meta-analysis of randomized clinical trials

Aims

Cavotricuspid isthmus (CTI) ablation is the current ablation treatment for typical atrial flutter (AFL). However, post-ablation atrial tachyarrhythmias, mostly in the form of atrial fibrillation (AF), are frequently observed after CTI ablation. We aimed to evaluate the effectiveness and safety of concomitant or isolated pulmonary vein isolation (PVI) in patients with typical AFL scheduled for ablation.

Methods and results

Electronic databases (PubMED, EMBASE, Clinicaltrials.gov) were searched through July, 2024. Randomized controlled trials (RCTs) were eligible if comparing PVI ± CTI ablation vs. CTI alone. The primary outcomes were any sustained atrial arrhythmia, typical AFL relapse, and AF. Secondary outcomes were need for redo-ablation or antiarrhythmic drugs. Random-effects and fixed-effects meta-analyses were undertaken for each individual outcome. Seven RCTs, with a total of 902 patients, were included. Comparing to CTI ablation alone, PVI ± CTI was more effective in preventing atrial tachyarrhythmias [risk ratio (RR) = 0.57, 95% CI: 0.41-0.79, P = 0.0007, I 2 = 50%, number needed to treat (NNT) = 4.1]. The results were driven mainly by a reduction of new onset/recurrent AF (RR = 0.41, 95% CI: 0.27-0.61, P < 0.0001, I 2 = 0%, NNT = 3.3), whereas there were no differences in typical AFL relapse (RR = 1.52, 95% CI: 0.63-3.66, P = 0.35, I 2 = 9%). Major complication rate was low and comparable across groups, although uncomplicated pericardial effusion was higher in PVI ± CTI (1.8% vs. 0.0%, P = 0.04). Results were comparable for the sub-analysis of PVI alone vs. CTI ablation.

Conclusion

In patients with typical AFL, PVI ± CTI ablation is more effective than CTI alone in reducing the atrial tachyarrhythmias and subsequent AF during follow-up, without affecting major complications rate. These results set the rationale for a well-designed, larger-scale RCT comparing both strategies.

Cavotricuspid Isthmus-Dependent Atrial Flutter. Beyond Simple Linear Ablation

The demonstration of a peritricuspid circular movement with a zone of slow conduction in the cavotricuspid isthmus, together with the high efficacy of linear ablation and widely accepted acute endpoints, has established typical flutter as a disease with a well-defined physiopathology and treatment. However, certain aspects regarding its deeper physiopathology, ablation targets, and methods for verifying the results remain to be clarified. While current research efforts have primarily been focused on the advancement of effective ablation techniques, it is crucial to continue exploring the intricate electrophysiological, ultrastructural, and pharmacological pathways that underlie the development of atrial flutter. This ongoing investigation is essential for the development of targeted preventive strategies that can act upon the specific mechanisms responsible for the initiation and maintenance of this arrhythmia. In this work, we will discuss less ascertained aspects alongside the most widely recognized general data, as well as the most recent or less commonly used contributions regarding the electrophysiological evaluation and ablation of typical atrial flutter. Regarding electrophysiological characteristics, one of the most intriguing findings is the presence of low voltage zones in some of these patients together with the presence of a functional, unidirectional line of block between the two vena cava. It is theorized that episodes of paroxysmal atrial fibrillation can trigger this line of block, which may then allow the onset of stable atrial flutter. Without this, the patient will either remain in atrial fibrillation or return to sinus rhythm. Another of the most important pending tasks is identifying patients at risk of developing post-ablation atrial fibrillation. Discriminating between individuals who will experience a complete arrhythmia cure and those who will develop atrial fibrillation after flutter ablation, remains essential given the important prognostic and therapeutic implications. From the initial X-ray guided linear cavotricuspid ablation, several alternatives have arisen in the last decade: electrophysiological criteria-directed point applications based on entrainment mapping, applications directed by maximum voltage criteria or by wavefront speed and maximum voltage criteria (omnipolar mapping). Electro-anatomical navigation systems offer substantial support in all three strategies. Finally, the electrophysiological techniques to confirm the success of the procedure are reviewed.