Is Dual Site Better Than Single Site Atrial Pacing in the Prevention of Atrial Fibrillation?

Long-term prevention of atrial fibrillation is not constantly realized by single-site right atrial pacing, and the beneficial role of multisite atrial pacing is still being studied. Accordingly, we compared the effectiveness of dual site and single site atrial pacing in 83 patients (50 men, 33 women, aged 69 +/- 10 years), who received a DDD device for primary sinus node dysfunction or bradycardia with documented atrial fibrillation. Inclusion criteria for dual site pacing were a sinus P wave > or = 120 ms and at least two episodes of documented paroxysmal AF in the 6 months preceding implantation. Dual site atrial pacing (high right atrium-coronary sinus ostium) was performed in 30 cases, and was compared to 53 single site paced patients, 21 with a P wave > or = 120 ms and 32 with a P wave < 120 ms. The basic pacing rate was programmed at 68 +/- 4 beats/min (range 60-75 beats/min). Sinus P wave (133 +/- 20 vs 95 +/- 9 ms; P < 0.001), paced P wave (107 +/- 14 vs 99 +/- 15; P < 0.05), number of antiarrhythmic drugs used (2.4 +/- 1.2 vs 1.6 +/- 1.5, P < 0.05), and the duration of symptoms (8.1 +/- 4.5 vs 3.8 +/- 2.4 years; P < 0.001) were significantly higher in dual site patients. The other characteristics were similar. During the follow-up of 18 +/- 15 months (range 3-30 months), paroxysmal AF was documented in 33 patients. Among these patients, 13 developed permanent AF following at least one episode of paroxysmal AF. When comparing dual site patients and single site patients with a P wave duration > or = 120 ms, paroxysmal AF incidence was lower in the dual site group (9/30 patients vs 15/21 patients, P < 0.01), as well as permanent AF (1/30 patients vs 8/21 patients, P < 0.01). By contrast, comparison between dual site patients and the group of single site patients with a P wave duration < 120 ms did not evidence any significant differences in paroxysmal (9/30 patients vs 9/32 patients) and permanent (1/30 patients vs 4/32 patients) AF incidences. Dual site seems better able than single site atrial pacing to improve the natural history of patients with a prolonged P wave, reducing the incidence of paroxysmal and permanent AF. No benefit could be expected in patients with a normal P wave duration.     

Primary Prevention of Atrial Fibrillation: Does the Atrial Lead Position Influence the Incidence of Atrial Arrhythmias in Patients with Sinus Node Dysfunction? Results from the PASTA Trial

Introduction: PASTA (pacing of the atria in sinus node disease) is a prospective and randomized trial, assessing the effect of different atrial lead positions on the atrial fibrillation (AF) incidence in patients with sinus node disease (SND). Method: The atrial lead position is randomized to: (a) free right atrial wall, (b) right atrial appendage (RAA), (c) coronary sinus ostium (CS‐Os), or (d) dual site right atrial pacing (CS‐Os + RAA). The pacemakers (Vitatron Selection 9000 or Prevent AF, Vitatron B.V., Arnhem, The Netherlands) are programmed in DDDR 70 mode and the total follow‐up duration is 24 months. To describe the atrial rhythm state, pacemaker‐derived data (arrhythmia counter) were assessed for AF episodes. AF was considered as evident, if the AF burden (time in AF related to follow‐up interval) was >1% (i.e., 15 min/d). Follow‐up data after 24 months were evaluated. Results: The analysis evaluates 142 patients (77 male, 74.5 ± 7.8 years). There was no statistical significant difference with respect to the occurrence of AF between the four groups after 24 months (A: 36%; B: 38%, C: 32%, D: 48%). The percentage of atrial/ventricular pacing was in A: 78/76%, in B: 84/81%, in C: 70/65%, and in D: 79/69%. These differences were not significant. Conclusion: The evaluation of the AF burden >1% and the total AF burden after 24 months did not show differences in the incidence of AF in patients with dual chamber pacemaker therapy for SND. We were not able to demonstrate a significant influence of right atrial lead position on the incidence of AF recurrence.     

Is Ablation of Atrial Flutter Always Safe?

Background: Radiofrequency ablation of typical atrial flutter is largely used and is considered as safe. The purpose of the study was to evaluate the prevalence and the causes of severe adverse event (AE) following atrial flutter ablation. Methods: Ablation of typical flutter was performed by conventional method with an 8-mm-tip electrode catheter, a maximum power of 70 W, and a maximum target temperature of 70° for 60 seconds in 883 patients, (685 males and 198 females aged from 18 to 93 years [64 ± 11.5]; 664 had heart disease [HD]). Results: AE occurred in 44 patients (5%). AE was life threatening in 14 patients: poorly tolerated bradycardia (transient complete atrioventricular block [AVB] or sinus bradycardia [SB] <40 beats per minute) associated with cardiac shock and acute renal failure in five patients, tamponade (n = 1), bleeding leading to death (n = 1), various AE-related deaths (n = 2), ventricular tachycardia-related death (n = 1), definitive complete AVB (n = 3), and right coronary artery occlusion-related complete AVB (n = 1). Less serious AE occurred in 30 patients: transitory major SB or second- or third-degree AVB (n = 23), bleeding (n = 4), transient ischemic attack (n = 1), and various AE (n = 2). Most of the bradycardia was related to β-blockers or other antiarrhythmic drugs used to slow atrial flutter. Factors of AE were female gender (36% vs 22%, P < 0.02) and the presence of ischemic (P < 0.03) or valvular HD (P < 0.01). Conclusions: AE following atrial flutter ablation occurred in 5% of patients. Most of them are avoidable by control of anticoagulants and arrest of rate-control drugs used to slow the rate of atrial flutter. (PACE 2012; 35:1061-1066).     

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.     

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 .     

Upstream Effect for Atrial Fibrillation: Still a Dilemma?

Atrial fibrillation is the most common arrhythmia in clinical practice. Ion channel blocking agents are often characterized by limited long-term efficacy and several side effects. In addition, ablative invasive procedures are neither easily accessible nor always efficacious. The "upstream therapy," which includes angiotensin-converting enzyme inhibitors, aldosterone receptor antagonists, statins, glucocorticoids, and ω-3 poly-unsaturated fatty acids, targets arrhythmia substrate, influencing atrial structural and electrical remodeling that play an essential role in atrial fibrillation induction and maintenance. The mechanisms involved and the most important clinical evidence regarding the upstream therapy influence on atrial fibrillation are presented in this review. Some open questions are also proposed.     

Atrial fibrillation in the elderly – Not a benign condition

Atrial fibrillation (AF) is the most commonly seen arrhythmia and its prevalence increases with age. In the general population, rates of 1–2% are reported but in older patients, the rates increase to over 10% (in those aged 85 years or older). Many older patients present to the emergency department (ED) with complaints that could be caused or associated with AF including valvular heart disease, hypertension, heart failure, an underlying infection (urinary or chest) and thyroid disorder. The most devastating complication of AF is stroke and early detection of AF and initiation of treatment (specifically the use of anti-coagulant medication) can significantly reduce the risk. AF is associated with high healthcare costs and has significant impacts on disability and quality of life especially if a stroke occurs.This review aims to describe the aetiology and treatment options for patients with newly diagnosed and previously diagnosed AF with an emphasis on how ED staff can manage older patients with AF and ensure optimal care is given. The treatment of AF has three main considerations (i) appropriateness for thromboembolic prophylaxis, (ii) rate control (including anti-arrhythmics, cardiac glycosides, B blockers and calcium channel blockers) and (iii) rhythm control with traditional cardioversion (either electrically or pharmacologically) or utilising interventional means to maintain sinus rhythm with cardiac surgery and more recently radio-frequency ablation. As anti-coagulation is widely implemented, the risks and benefits associated with warfarin and the newer agents will be described.Given that more than half of those with AF are over 75 years and 30% of AF is diagnosed incidentally, there is an imperative for prompt diagnosis to reduce the risk of debilitating complications especially stroke. AF should not be viewed as yet another concomitant “benign” condition. Emergency staff are well placed to detect AF and ensure appropriate treatment is commenced to reduce the adverse events associated with it.     

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.

Is Emergency Department Cardioversion of Recent-onset Atrial Fibrillation Safe and Effective?

Background

Atrial fibrillation (AF) is a very common dysrhythmia presenting to Emergency Departments (EDs). Controversy exists regarding the optimal clinical therapy for these patients, which typically focuses on rhythm rate-control and admission or cardioversion and discharge home.

Clinical Question

Is ED cardioversion of recent-onset atrial fibrillation safe, effective, and does it result in positive meaningful patient outcomes?

Evidence Review

Five observation studies with nearly 1600 ED patients with atrial fibrillation treated with either rate-control or cardioversion were reviewed and results compiled.

Results

Overall, ED cardioversion for recent-onset AF seems safe and effective, with success rates ranging from 85.5% to 97% in these studies. Although further research should seek to identify patients at low risk for thromboembolic complication, more rigorously assess patient satisfaction, and show cost savings, emergency physicians should feel comfortable using this approach in select patients.

Conclusion

ED cardioversion for recent-onset AF seems safe and effective.     

Atrial Lead Placement During Atrial Fibrillation. Is Restitution of Sinus Rhythm Required for Proper Lead Function? Feasibility and 12‐Month Functional Analysis

Unexpected atrial fibrillation (AF) during implantation of an atrial pacemaker lead is sometimes encountered. Intraoperative cardioversion may lengthen and complicate the implantation process. This study prospectively investigates the performance of atrial leads implanted during AF (group A) and compares atrial sensing and pacing properties to an age- and sex-matched control group in which sinus rhythm had been restored before atrial lead placement (group B). Patient groups consisted of 32 patients each. All patients received DDDR pacemakers and bipolar, steroid-eluting, active fixation atrial leads. In patients with AF at the time of implantation (group A), a minimal intracardiac fibrillatory amplitude of at least 1.0 mV was required for acceptable atrial lead placement. In patients with restored sinus rhythm (group B), a voltage threshold < 1.5 V at 0.5 ms and a minimal atrial potential amplitude > 1.5 mV was required. Patients of group A in whom spontaneous conversion to sinus rhythm did not occur within 4 weeks after implantation underwent electrical cardioversion to sinus rhythm. Pacemaker interrogations were performed 3, 6, and 12 months after implantation. In group A, implantation time was significantly shorter as compared to group B (58.7 +/- 8.6 minutes vs 73.0 +/- 17.3 minutes, P < 0.001). Mean atrial potential amplitude during AF was correlated with the telemetered atrial potential during sinus rhythm (r = 0.49, P < 0.001), but not with the atrial stimulation threshold. Twelve months after implantation, sensing thresholds (1.74 +/- 0.52 mV vs 1.78 +/- 0.69 mV, P = 0.98) and stimulation thresholds (1.09 +/- 0.42 V vs 1.01 +/- 0.31 V, P = 0.66) did not differ between groups A and B. However, in three patients of group A, chronic atrial sensing threshold was < or = 1 mV requiring atrial sensitivities of at least 0.35 mV to achieve reliable atrial sensing. Atrial lead placement during AF is feasible and reduces implantation time. However, bipolar atrial leads and the option to program high atrial sensitivities are required.