Is There a Role for Statins in Atrial Fibrillation?

3-Hydroxy-3-methyl-glutaryl-CoA reductase inhibitors (statins) are some of the most commonly prescribed drugs in the world. While lipid modification remains the primary function of statins, there has been increasing interest in its potential pleiotropic effects, particularly as an anti-inflammatory agent in its role as an antiarrhythmic. Atrial fibrillation (AF) is the most common arrhythmia encountered in clinical practice and carries with it a significant burden in both morbidity and mortality. Treatment for AF currently involves either rate or rhythm control where both have demonstrable associated risks. Rate control necessitates anticoagulation, which can cause life-threatening bleeding, while rhythm control has a poor side-effect profile that may lead to greater mortality and may not completely eliminate the need for anticoagulation. Considering this pressing need for novel therapeutic interventions in AF, this long overdue systematic review explores the potential role of statins in the treatment and prevention of AF. Physicians, especially cardiologists, need to be aware of the host of currently available literature and, more importantly, need to be stimulated to generate discussion and formulate studies that will help debate the issues under the most erudite standards .     

Bachmann's Bundle: Does It Play a Role in Atrial Fibrillation?

BACKGROUND: Cardiac anatomists have known the presence of a group of specialized fibers connecting the right and left atrium for years. However, only recently have clinical cardiologists come to recognize the potential importance of this specialized conduction system. Anatomical and microscopic studies have shown that the Bachmann's bundle (BB) represents a distinct structure similar to the atrio-ventricular node and the His-Purkinje conduction system but without any insulating tissue. RESULTS: BB cells have specialized electrophysiological properties like supernormal excitability and faster longitudinal conduction that can facilitate more rapid impulse transmission compared to the normal atrial tissue. Experimental blockage of this pathway causes prolongation and widening of the P wave, which is associated with an increased incidence of atrial fibrillation. Atrial pacing is effective in reducing the incidence of atrial fibrillation by preventing bradycardia, synchronizing the atria, limiting anisotropy and reducing the dispersion of refractoriness. Various animal and human studies have shown pacing near the right atrial insertion of BB to have a beneficial effect in patients with interatrial conduction delay and atrial tachyarrhythmias. This mode of atrial septal pacing is convenient, safe, reliable, and clinically as effective as multisite pacing. CONCLUSION: This article is an effort to define the special properties of BB and its possible role in prevention of atrial fibrillation by permanent pacemakers.     

Early Recurrences after Paroxysmal Atrial Fibrillation Ablation: When is the Proper Timing for Reablation?

Background: Early recurrences (ERs) within 1 month after paroxysmal atrial fibrillation (AF) ablation are common and may subside in a considerable proportion of patients. Although late reablation after 3 months is recommended, the proper timing for reablation remains undetermined. Methods and Results: One hundred and seventeen (31.2%) from the pool of 375 patients experienced ERs at 7.5 ± 5.5 days postablation. They were allocated into two groups randomly: early reablation group (ERe+) (n = 57) and nonearly reablation group (ERe?) (n = 60). Forty patients (70.2%) in ERe+ group underwent early reablation at 28.1 ± 2.7 days postablation. Forty patients (66.7%) in ERe? group underwent late reablation at 98.2 ± 5.2 days postablation. The proportion of reablation was comparable (P = 0.68). ERs subsided in 17 (29.8%) in ERe+ group and in 20 (33.3%) in ERe? group. In ERe+ group, PV reconnection in 36 (80.0%), non‐PV foci in six (10.5%), and right or left atrial flutter in five (8.8%) was abolished by ablation. In ERe? group, pulmonary vein (PV) reconnection in 29 (72.5%), non‐PV foci in eight (13.3%), and right or left atrial flutter in eight (13.3%) was ablated successfully. The proportion of PV reconnection, nonfoci, and atrial flutter was comparable, P = 0.45, 0.64, and 0.56, respectively. At the end of 16.5 ± 2.0 (ERe+ group) and 15.2 ± 2.6 (ERe? group) months’ follow‐up, 47 (82.5%) in ERe+ group and 51 (85%) in ERe? group were free of atrial tachyarrhythmias, P = 0.70. Conclusions: Compared with reablation 2 months later after initial ablation, early reablation at ≈1 month had similar clinical effectiveness. The proper timing for reablation can be set at ≈1 month after initial paroxysmal AF ablation. (PACE 2011; 709–716)     

Sensing of Atrial Fibrillation by a Dual Chamber Pacemaker: How Should Atrial Sensing Be Programmed to Ensure Adequate Mode Shifting?

Patients with atrial fibrillation and a DDDR pacemaker were studied to assess mode switching at different atrial sensitivity settings. Thirty-one patients were investigated 7 +/- 9 months after pacemaker implantation and 20 of those patients were reinvestigated 23 +/- 9 months after implant. Adequate mode switching was evaluated by stepwise programming the atrial sensitivity setting from maximal to minimal in the bipolar mode. Adequate mode switching was observed in all 31 patients during the first evaluation. The lowermost sensitivity average allowing for mode switching was 1.1 +/- 0.7 mV (range 0.3-4.0 mV). A total of 22 (71%) patients demonstrated intermittent mode shifting at sensitivity settings above the atrial sensing threshold. In six (19%) patients, the adequate sensitivity threshold ranged from 0.3 to 0.5 mV, which did not allow for a two-fold sensitivity safety margin. During the second evaluation, adequate mode switching was achieved in all 20 patients, the lowermost sensitivity average allowing for mode switching being 1.1 +/- 0.7 mV (range 0.3-2.0 mV). A total of 16 (80%) patients showed intermittent mode shifting at a sensitivity setting above the atrial sensing threshold. In five (25%) patients, the sensitivity threshold ranged from 0.3 to 0.5 mV, which did not allow for a two-fold sensitivity safety margin. Adequate mode switching was achieved in 31 of 31 patients in response to atrial fibrillation on one occasion and in all 20 patients on two occasions. It was necessary to program the atrial sensitivity to the highest possible level (0.3 mV) to ensured adequate mode switching in all cases.     

What is the Relationship of Atrial Flutter and Fibrillation?

Animal models and human studies of atrial activation mapping and entrainment have considerably enhanced our understanding of the anatomical substrate for atrial flutter and created the basis for a definite cure with radiofrequency catheter ablation. As atrial flutter has now become a curable arrhythmia, emphasis is shifting to understand the most common arrhythmia: atrial fibrillation. Furthermore, from clinical observation, it is apparent that there is a relationship between atrial fibrillation and atrial flutter in patients with atrial arrhythmias. Techniques that have informed our understanding of the anatomical basis of atrial flutter may also be useful in understanding the relationship between atrial fibrillation and flutter, including animal models, clinical endocardial mapping, and intracardiac anatomical imaging. Thus, atrial anatomy and its relationship to electrophysiological findings, and the role of partial or complete conduction barriers around which reentry can and cannot occur, may be of importance for atrial fibrillation as well. Ultimately, the relationship between atrial fibrillation and atrial flutter may inform our understanding of the mechanisms of atrial fibrillation itself, and help to develop new approaches to device, catheter-based, and pharmacological therapy for atrial fibrillation.     

Intravenous Flecainide for Emergency Department Management of Acute Atrial Fibrillation

Background

Atrial fibrillation (AF) is the most commonly encountered dysrhythmia in the emergency department, and its prevalence is increasing. A substantial proportion of these patients have recent-onset AF (<48 h). The poor prognosis associated with AF is being increasingly recognized, and there is some evidence for better outcomes in younger patients with recent-onset AF when sinus rhythm is restored. Flecainide is recommended in the latest international guidelines for cardioversion of recent-onset AF, but its safety and efficacy relative to other recommended agents are unclear.