Catheter Ablation for Persistent Atrial Fibrillation

Novel Pulmonary Delivery of Drugs for the Management of Atrial Fibrillation

Atrial fibrillation (AF) is the most prevalent cardiac arrhythmia, affecting approximately 335 million patients worldwide. Comprehensive pharmacological treatment of AF includes medications for rate or rhythm control and anticoagulants to reduce the risk of thromboembolism; yet, these agents have significant limitations. Oral anti-arrhythmic agents have a slow onset of action, and rapid onset formulations require hospitalization for intravenous therapy. Orally administered drugs also require high doses to attain therapeutic levels, and thus dose-related severe adverse effects are often unavoidable. Given the therapeutic benefits of inhaled drug delivery, including rapid onset of action and very low doses to achieve therapeutic efficacy, this review will discuss the benefits of novel pulmonary delivery of drugs for the management of AF.

Catheter Ablation of Ventricular Fibrillation

Ventricular fibrillation (VF) is a common cause of sudden cardiac death (SCD) and is unfortunately without a cure. Current therapies focus on prevention of SCD, such as implantable cardioverter-defibrillator (ICD) implantation and anti-arrhythmic agents. Significant progress has been made in improving our understanding and ability to target the triggers of VF, via advanced mapping and ablation techniques, as well as with autonomic modulation. However, the critical substrate for VF maintenance remains incompletely defined. In this review, we discuss the evidence behind the basic mechanisms of VF and review the current role of catheter ablation in patients with VF.

Clinical Relevance of Sinus Rhythm Mapping to Quantify Electropathology Related to Atrial Fibrillation

Progression of AF is accompanied by structural and electrical remodelling, resulting in complex electrical conduction disorders. This is defined as electropathology and it increases with the progression of AF. The severity of electropathology, thus, defines the stage of AF and is a major determinant of effectiveness of AF therapy. As specific features of AF-related electropathology are still unknown, it is essential to first quantify the electrophysiological properties of atrial tissue and then to examine the inter- and intra-individual variation during normal sinus rhythm. Comparison of these parameters between patients with and without a history of AF unravels quantified electrophysiological features that are specific to AF patients. This can help to identify patients at risk for early onset or progression of AF. This review summarises current knowledge on quantified features of atrial electrophysiological properties during sinus rhythm and discusses its relevance in identifying AF-related electropathology.

Management of atrial fibrillation-flutter: uptodate guideline paper on the current evidence

The term 'flutter' and 'fibrillation' were first coined to differentiate the differences between fast, regular contractions in Atrial Flutter (AFLUT) with irregular, vermiform contractions of Atrial Fibrillation (AFIB). Management of these two diseases has been a challenge for physicians. Rate control (along with rhythm control) is the first line of management for symptomatic AFIB/AFLUT with Rapid Ventricular Rate (RVR). In some situations, atrial rhythms may not be well controlled by these anti-arrhythmic drugs, making cardioversion to sinus rhythm necessary. Anti-coagulation therapy in both the disease population is essential. Catheter ablation is an effective treatment option in certain patients that have AFIB/AFLUT refractory to medical management. Newer techniques like left atrial appendage (LAA) has been developed and is a highly attractive concept for the future in the management of AFIB/AFLUT. Newer novel drugs targeting specific ion channels are approaching the stages of clinical investigation. However, while advances in technologies have helped elucidate many aspects of these diseases, many mysteries still remain. This literature review serves as one of the guideline papers for current up-to-date management on both AFIB and AFLUT.

Atrial fibrillation: review of current treatment strategies

Atrial fibrillation (AF) is the most prevalent cardiac arrhythmia in modern clinical practice, with an estimated prevalence of 1.5-2%. The prevalence of AF is expected to double in the next decades, progressing with age and increasingly becoming a global medical challenge. The first-line treatment for AF is often medical treatment with either rate control or anti-arrhythmic agents for rhythm control, in addition to anti-coagulants such as warfarin for stroke prevention in patient at risk. Catheter ablation has emerged as an alternative for AF treatment, which involves myocardial tissue lesions to disrupt the underlying triggers and substrates for AF. Surgical approaches have also been developed for treatment of AF, particularly for patients requiring concomitant cardiac surgery or those refractory to medical and catheter ablation treatments. Since the introduction of the Cox-Maze III, this procedure has evolved into several modern variations, including the use of alternative energy sources (Cox-Maze IV) such as radiofrequency, cryo-energy and microwave, as well as minimally invasive thoracoscopic epicardial approaches. Another recently introduced technique is the hybrid ablation approach, where in a single setting both epicardial thoracoscopic ablation lesions and endocardial catheter ablation lesions are performed by the cardiothoracic surgeon and cardiologist. There remains controversy surrounding the optimal approach for AF ablation, energy sources, and lesion sets employed. The goal of this article is review the history, classifications, pathophysiology and current treatment options for AF.

Prevalence and distribution of focal triggers in persistent and long-standing persistent atrial fibrillation

BACKGROUND

The relevance of focal triggers in persistent atrial fibrillation (PerAF) and long-standing persistent atrial fibrillation (LSPAF) has not been previously investigated.

OBJECTIVE

We prospectively evaluated the prevalence and distribution of AF triggers in patients referred for catheter ablation of PerAF and LSPAF.

METHODS

We analyzed consecutive patients undergoing first time AF ablation who underwent a standardized trigger protocol including cardioversion of induced or spontaneous AF and infusion of up to 20 μg of isoproterenol for 15-20 minutes either before or after pulmonary vein (PV) isolation accomplished. Triggers were defined as AF/sustained atrial tachyarrhythmia or repetitive atrial premature depolarizations.

RESULTS

A total of 2168 patients were included (mean age 57 ± 11 years; 1636 [75%] men), with 1531 patients having paroxysmal AF (PAF) (71%), 496 having PerAF (23%), and 141 having LSPAF (7%). PV triggers were found in 1398 patients with PAF (91%), 449 patients with PerAF (91%), and 129 patients with LSPAF (91%) (P = .856 for comparison across groups). Non-PV triggers were elicited in a total of 234 patients (11%), and the prevalence was similar across the different types of AF (PAF, 165 [11%]; PerAF, 54 [11%]; LSPAF, 15 [11%]; P = .996 for comparison across groups).

CONCLUSION

PVs are the main AF trigger site in patients with PerAF and LSPAF, with an overall prevalence similar to that found in patients with PAF. These results support the current recommendations for PV isolation as the cornerstone of catheter ablation to eliminate AF triggers in PerAF and LSPAF.

Catheter ablation of symptomatic postoperative atrial arrhythmias after epicardial surgical disconnection of the pulmonary veins and left atrial appendage ligation in patients with atrial fibrillation

OBJECTIVES

Minimally invasive thoracoscopic epicardial pulmonary vein isolation (MIPI) has an important role in the surgical treatment of atrial fibrillation (AF). However, the management of recurrent atrial arrhythmias after MIPI and long-term success rate of catheter ablation have not been well studied.

METHODS

Electrophysiological study was performed in 23 patients, 378 ± 282 days after MIPI surgery, because of recurrent symptomatic atrial arrhythmias.

RESULTS

A total of 20 patients presented with paroxysmal and persistent AF, 2 patients had a combination of AF and atrial tachycardia (AT) and 1 patient had a combination of AF and atrial flutter. All patients showed pulmonary vein (PV) reconnection. ATs were micro-re-entry PV-related ATs and atrial flutter was cavotricuspid isthmus dependent. Eighteen of 23 patients (78.3%) were free of atrial arrhythmias after one catheter ablation procedure at a mean follow-up of 50 ± 16 months. Three patients underwent a second ablation procedure for recurrent AF and macro-re-entry left atrial flutter. Eventually 20 of 23 patients (87%) remained free of atrial arrhythmias after a mean of 1.1 ± 0.3 ablation procedures.

CONCLUSIONS

Catheter ablation of recurrent atrial arrhythmias following MIPI for paroxysmal and persistent AF is a feasible and effective treatment with a good long-term success rate. Reconnection of PVs accounts for most recurrences.

Staged transthoracic approach to persistent atrial fibrillation (TOP-AF): study protocol for a randomized trial

Background

Persistent atrial fibrillation frequently shows multiple different electrophysiological mechanisms of induction. This heterogeneity causes a low success rate of single procedures of ablation and a high incidence of recurrence. Surgical ablation through bilateral thoracotomy demonstrates better results after a single procedure. Prospective observational studies in inhomogeneous populations without control groups report a remarkable 90% of success with hybrid or staged procedures of surgical ablation coupled with catheter ablation. In this trial, we will examine the hypothesis that a staged approach involving initial minimally invasive surgical ablation of persistent atrial fibrillation, followed by a second percutaneous procedure in case of recurrence, has a higher success rate than repeated percutaneous procedures.

Methods/Design

This is a controlled (2:1) randomized trial comparing use of a percutaneous catheter with minimally invasive transthoracic surgical ablation of persistent atrial fibrillation. The inclusion and exclusion criteria, definitions, and treatment protocols are those reported by the 2012 Expert Consensus Statement on catheter and surgical ablation of atrial fibrillation. Patients will be randomized to either percutaneous catheter (n = 100) or surgical (n = 50) ablation as the first procedure. After 3 months, they are re-evaluated, according to the same guidelines, and receive a second procedure if necessary. Crossover will be allowed and data analyzed on an “intention-to-treat” basis. Primary outcomes are the incidence of sinus rhythm at 6 and 12 months and the proportions of patients requiring a second procedure.

Discussion

The use of a staged strategy combining surgical and percutaneous approaches might be more favorable in treatment of persistent atrial fibrillation than the controversial single percutaneous ablation.

Trial registration

ISRCTN08035058 Reg 06.20.2013

Do we need assessment of nonpulmonary vein triggers for successful ablation of atrial fibrillation?

Evaluation of: Chang HY, Lo LW, Lin YJ et al. Long-term outcome of catheter ablation in patients with atrial fibrillation originating from nonpulmonary vein ectopy. J. Cardiovasc. Electrophysiol. 24, 250-258 (2013). Targeting of nonpulmonary vein (NPV) arrhythmogenic sites that are responsible for triggering and perpetuating atrial fibrillation (AF) is an essential part of catheter ablation for persistent AF. It also has the potential to increase the success rate of ablation in the case of paroxysmal AF. The study by Chang et al. provides detailed data on the prevalence of NPV triggers in a large cohort of patients undergoing radiofrequency catheter ablation for AF. The presence of NPV triggers was strongly and independently associated with a higher AF recurrence rate, despite being targeted at index procedure. Controversies in the optimum strategy of ablation for persistent AF are discussed. New sophisticated methods for focal impulse and rotor mapping are mentioned that will hopefully assist in more efficient AF ablation procedures by facilitating the assessment and selective targeting of arrhythmogenic substrates, especially in the case of persistent AF.