High-density Mapping Guided Pulmonary Vein Isolation for Treatment of Atrial Fibrillation - Two-year clinical outcome of a single center experience

A review regarding the article 'Multidisciplinary management strategies for atrial fibrillation.'

Catheter ablation has become an accepted first line therapy for paroxysmal atrial fibrillation (PAF), with pulmonary vein isolation (PVI) being the key element of ablation strategies. Catheter ablation of AF has been proven to be superior to antiarrhythmic drug (AAD) therapy regarding efficacy and improvement of survival in patients with heart failure. PVI has become a routine treatment procedure in recent decades especially for patients with symptomatic PAF. Recent research investigations have shown that AF recurrence still occurs in a significant number of patients after ablation. AF recurrence leads to a decrease in patients' quality of life and is related to an increased risk of cardiovascular events and mortality. As most arrhythmia recurrences take place within the first 3 months after the initial procedure, this time period is seen as a so-called "blanking period", in which ablation is not recommended, since up to 50 % of patients can become arrhythmia free in the long run. Ablation therapy, however, is less successful in patients suffering from long standing persistent AF, with a 20.3 % success rate after a single procedure and a 45 % success rate after multiple RFA procedures. Several scores have been established and validated to predict cardiac rhythm outcomes after catheter ablation. However, due to the lack of external validation of most of the scores, their efficacy in predicting recurrence of atrial fibrillation needs to be further evaluated in independent external studies.

A U.K. Multicenter Retrospective Study of the Learning Curve and Relative Impact on Success Rates and Procedural Metrics of the RHYTHMIA HDx™ Mapping System

The learning curve for the novel RHYTHMIA HDx™ 3-dimensional electroanatomic system is unknown. Retrospective data collection was carried out at 3 U.K. centers from the introduction of RHYTHMIA HDx™ (Boston Scientific, Marlborough, MA, USA) and associated mapping and ablation catheters. Patients were matched with controls using the CARTO^® 3 mapping system (Biosense Webster Inc., Diamond Bar, CA, USA). Fluoroscopy, radiofrequency ablation, and procedure times; acute and long-term success; and complications were assessed. A total of 253 study patients along with 253 controls were included. Significant correlations existed between procedural efficiency metrics and center experience for de novo atrial fibrillation (AF) ablation (procedure time, Spearman's ρ = -0.624; ablation time, ρ = -0.795; both P < .0005) and de novo atrial flutter (AFL) ablation (ablation time, ρ = -0.566; fluoroscopy time, ρ = -0.520; both P = .001). No correlations existed for other assessed atrial arrhythmias. For de novo AF and AFL, metrics significantly improved after 10 procedures in each center (procedure time [AF only, P = .001], ablation time [AF, P < .0005; AFL, P < .0005], and fluoroscopy time [AFL only, P = .0022]) and became comparable to those of controls. Acute success and long-term success did not experience significant improvements with experience, but they were comparable to the control group throughout. Complications with RHYTHMIA HDx™ were comparable to those associated with CARTO^® 3. In conclusion, a short learning curve exists with the use of RHYTHMIA HDx™ for standardized procedures (de novo AF/AFL). Procedural performance improved and became comparable to that seen with CARTO^® 3 following 10 cases at each center. Clinical outcomes at 6 and 12 months and complications were no different from those observed in controls.

Mapping strategies and ablation of premature atrial complexes

Premature atrial complexes (PACs) are a common finding in patients with structural heart disease, as well as in healthy subjects. In addition to the clinical spectrum ranging from asymptomatic patients to irritating palpitations, PACs are suggested to be associated with an increased risk of atrial fibrillation and stroke. Medical treatment leads to a significant reduction in PACs with clear symptom relief in a large proportion of patients, but is limited in cases of PACs that are refractory to antiarrhythmic drug (AAD) treatment. Furthermore, proarrhythmic effects of AAD or the patient's refusal of AAD treatment due to side effects need to be considered. Ablation of PACs is a good alternative to medical therapy with a comparable safety profile and at least comparable efficacy. In recent years, ultra-high-density (UHD) mapping with multiple improvements for successful ablation has been evolving. Before the introduction of UHD mapping, ablation strategies included activation mapping with single-tip catheters or conventional mapping aiming for the earliest activation of the PAC locally, with the earliest activation suspected to be the origin of the PAC and targeted by radiofrequency (RF) ablation. Using UHD mapping, a three-dimensional local activation map of the atrium can be acquired, identifying the point of earliest activation within the high-resolution map. PAC ablation has therefore developed into a true alternative for the treatment of symptomatic PACs.

Basket catheter-guided ultra-high-density mapping of cardiac arrhythmias: a systematic review and meta-analysis

Aim: Ultra-high-density mapping (HDM) is increasingly used for guidance of catheter ablation in cardiac arrhythmias. While initial results are promising, a systematic evaluation of long-term outcome has not been performed so far. Methods: A systematic review and meta-analysis was conducted on studies investigating long-term outcome after Rhythmia HDM-guided atrial fibrillation (AF) or atrial tachycardia catheter ablation. Results: Beyond multiple studies providing novel insights into arrhythmia mechanisms, follow-up data from 17 studies analyzing Rhythmia HDM-guided ablation (1768 patients, 49% with previous ablation) were investigated. Cumulative acute success was 100/90.2%, while 12 months long-term pooled success displayed at 71.6/71.2% (AF/atrial tachycardia). Prospective data are limited, showing similar outcome between HDM-guided and conventional AF ablation. Conclusion: Acute results of HDM-guided catheter ablation are promising, while long-term success is challenged by complex arrhythmogenic substrates. Prospective randomized trials investigating different HDM-guided ablation strategies are warranted and underway.