ACC/AHA/ESC 2006 Guidelines for the Management of Patients with Atrial Fibrillation: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines and the European Society of Cardiology Committee for Practice Guidelines (Writing Committee to Revise the 2001 Guidelines for the Management of Patients With Atrial Fibrillation): developed in collaboration with the European Heart Rhythm Association and the Heart Rhythm Society

A prospective, randomized trial of an emergency department observation unit for acute onset atrial fibrillation

STUDY OBJECTIVE

An emergency department (ED) observation unit protocol for the management of acute onset atrial fibrillation is compared with routine hospital admission and management.

METHODS

Adult patients presenting to the ED with atrial fibrillation of less than 48 hours' duration without hemodynamic instability or other comorbid conditions requiring hospitalization were enrolled. Participants were randomized to either ED observation unit care or routine inpatient care. The ED observation unit protocol included pulse rate control, cardiac monitoring, reassessment, and electrical cardioversion if atrial fibrillation persisted. Patients who reverted to sinus rhythm were discharged with a cardiology follow-up within 3 days, whereas those still in atrial fibrillation were admitted. All cases were followed up for 6 months and adverse events recorded.

RESULTS

Of the 153 patients, 75 were randomized to the ED observation unit and 78 to routine inhospital care. Eighty-five percent of ED observation unit patients converted to sinus rhythm versus 73% in the routine care group (difference 12%; 95% confidence interval [CI] -1% to 25%]; P=.06). The median length of stay was 10.1 versus 25.2 hours (difference 15.1 hours; 95% CI 11.2 to 19.6; P<.001) for ED observation unit and inhospital care respectively. Nine ED observation unit patients required inpatient admission. Eleven percent of the ED observation unit group had recurrence of atrial fibrillation during follow-up versus 10% of the routine inpatient care group (difference 1%; 95% CI -9% to 11%; P=.93). There was no significant difference between the groups in the frequency of hospitalization or the number of tests, and the number of adverse events during follow-up was similar in the 2 groups.

CONCLUSION

An ED observation unit protocol that includes electrical cardioversion is a feasible alternative to routine hospital admission for acute onset of atrial fibrillation and results in a shorter initial length of stay.

Use of anticoagulation in elderly patients with atrial fibrillation who are at risk for falls

OBJECTIVE

To evaluate data addressing use of anticoagulation in elderly patients with atrial fibrillation (AF), in particular those at risk of falls.

DATA SOURCES

Primary literature was identified through PubMed MEDLINE (1966-December 2007) and EMBASE (1980-December 2007) using the search terms anticoagulation, warfarin, aspirin, elderly, falls, older persons, atrial fibrillation, bleeding, education, stroke, and use. Additional references were obtained through review of references from articles obtained.

STUDY SELECTION AND DATA EXTRACTION

Clinical studies evaluating warfarin and aspirin efficacy in AF, as well as studies evaluating anticoagulation and falls, elderly patients, and bleeding were considered for inclusion. Selection emphasis was placed on randomized studies of AF and those evaluating anticoagulation and falls.

DATA SYNTHESIS

Uncertainties over the optimal treatment for elderly patients with AF still exist. Variance in the guidelines is reflected in current practice, as some discrepancies are present. Warfarin is underprescribed in elderly patients, with only about 50% of eligible patients receiving therapy. Falls are most often cited as the reason for not using anticoagulants in an elderly patient. Three risk-benefit analyses have been performed, and all found that despite risks associated with warfarin, its benefits outweigh its risks even in patients who fall. Warfarin should be used rather than aspirin or no therapy in elderly patients at risk of falls. Anticoagulation education has been shown to reduce the risk of bleeding in the elderly and should be a vital part of warfarin management.

CONCLUSIONS

The risk of falls alone should not automatically disqualify a person from being treated with warfarin. While falls should not dictate anticoagulant choice, assessment and management of fall risk should be an important part of anticoagulation management. Efforts should be made to minimize fall risk.

AFFECT: a prospective, open-label, multicenter trial to evaluate the feasibility and safety of a short-term treatment with subcutaneous certoparin in patients with persistent non-valvular atrial fibrillation

BACKGROUND

Patients with persistent atrial fibrillation (AF) scheduled for electrical cardioversion need immediate anticoagulation. Unfractionated heparin (UFH) is often used for early anticoagulation in these patients before oral anticoagulation becomes effective. However, dose adjustment is required to achieve a two- to three-fold prolongation of the activated partial thromboplastin. Low molecular weight heparins, given in body weight-adjusted or independent fixed dosage, require less laboratory monitoring and are also effective within hours of first dosing. They seem to be an attractive alternative to UFH. Previous evidence has shown that these drugs are safe and effective in this indication.

PATIENTS AND METHODS

In this prospective, open-label, multicenter pilot study, 203 patients were enrolled with persistent non-valvular AF scheduled for electrical cardioversion. Patients received a fixed dose of 8000 U anti-Xa certoparin twice daily starting immediately after enrolment and before cardioversion was performed. Patients with AF > 48 h underwent transoesophageal echocardiography (TEE) before cardioversion to exclude intra-atrial thrombi. After cardioversion, overlapping oral anticoagulation was started. Treatment with certoparin was stopped only after two consecutive days with INR values >2.

OBJECTIVES

The objective was to document the feasibility and safety of a short-term treatment with a fixed, body weight-independent certoparin regimen (2 x 8000 U anti-Xa).

RESULTS

Out of 203 patients enrolled, 200 received at least one dose of certoparin and were included in the analysis (safety population). Median treatment duration with certoparin was 7 days. Bleedings were observed in 8 patients (4.0%) and were classified as major (1.5%) or minor (2.5%). Cerebral ischemia was reported for 1 patient (0.5%). One patient showed mild thrombocytopenia (0.5%). There were no reports of venous thromboembolism or death during the treatment period.

CONCLUSION

Certoparin administered at 8000 U anti-Xa twice daily independent of body weight was safe and appeared to be effective in patients with non-valvular AF undergoing electrical cardioversion. Its ease of use and the possibility of treatment on an outpatient basis make it an attractive option for early anticoagulation in AF.

Effect of ximelagatran on ischemic events and death in patients with atrial fibrillation after acute myocardial infarction in the efficacy and safety of the oral direct thrombin inhibitor ximelagatran in patients with recent myocardial damage (ESTEEM) trial

BACKGROUND

New-onset trial fibrillation (AF) occurs commonly after acute myocardial infarction (MI) and is associated with a poor prognosis due to stroke or death. The optimal antithrombotic therapy is unknown. The aim of this study was to investigate whether an oral direct thrombin inhibitor, ximelagatran, added to aspirin, reduced the risk of death, myocardial infarction (MI), and stroke in patients who developed AF after their qualifying MI in the efficacy and safety of the oral direct thrombin inhibitor ximelagatran in patients with recent myocardial damage (ESTEEM) trial.

METHODS

The ESTEEM trial evaluated 6 months treatment with ximelagatran together with aspirin, compared to aspirin alone, for prevention of ischemic events in 1883 patients randomized within 14 days after an MI. After their qualifying MI, 174 (9%) patients developed AF in hospital. Multivariate hazard ratios for ximelagatran compared with placebo were calculated by presence AF.

RESULTS

Of 101 patients with AF treated with ximelagatran 7 (6.9%) had either death, MI, or stroke, compared with 15 (20.6%) in 73 patients allocated to placebo. Ximelagatran reduced the risk of death, MI, or stroke by 70% (hazard ratio 0.30, 95% CI 0.12-0.74). For the separate outcome events, we found similar, nonsignificant trends. One major bleeding event occurred in each treatment group.

CONCLUSIONS

For patients with MI complicated by AF, the combination of aspirin and an oral direct thrombin inhibitor seems beneficial. The high risk for death, MI, and stroke in this population and the increasing use of percutaneous interventions in MI patients may suggest a combination of long-term antiplatelet and anticoagulant therapy. Randomized clinical trials are warranted.

Electrical and pharmacologic cardioversion for atrial fibrillation

In this article, electrical and pharmacologic cardioversion for atrial fibrillation is described in detail. Indications for cardioversion and management of pericardioversion anticoagulation also are discussed. Finally, management strategies for immediate recurrence of atrial fibrillation and cardioversion failure are offered.

Status of the epidemiology of atrial fibrillation

Atrial fibrillation (AF), an increasingly common dysrhythmia, is responsible for substantial morbidity and mortality. Currently in the United States, approximately 2.3 million people are diagnosed with AF and, based on the census, this number may rise to 5.6 million by 2050. Risk factors for AF include advancing age and cardiovascular disease and its risk factors. The chief hazard of AF is embolic stroke, which is increased four- to fivefold, assuming great importance in advanced age when it becomes a dominant factor. AF is associated with about a doubling of mortality.

Atrial fibrillation: goals of therapy and management strategies to achieve the goals

The primary goals in the management of patients who have atrial fibrillation are prevention of stroke and cardiomyopathy and amelioration of symptoms. Each patient presents to a physician with a specific constellation of symptoms and signs, but, fortunately, most patients can be assigned to broad categories of therapy. For some, anticoagulation and rate control suffice, whereas others require more aggressive attempts to restore and maintain sinus rhythm. Physicians and patients need to be willing to alter therapeutic plans if an initial strategy of rate or rhythm control is unsuccessful.

Barriers to the Use of Anticoagulation for Nonvalvular Atrial Fibrillation

Background and Purpose— Anticoagulation reduces the risk of stroke in nonvalvular atrial fibrillation yet remains underused. We explored barriers to the use of anticoagulants among Australian family physicians.

Methods— The authors conducted a representative, national survey.

Results— Of the 596 (64.4%) eligible family physicians who participated, 15.8% reported having a patient with nonvalvular atrial fibrillation experience an intracranial hemorrhage with anticoagulation and 45.8% had a patient with known nonvalvular atrial fibrillation experience a stroke without anticoagulation. When presented with a patient at “very high risk” of stroke, only 45.6% of family physicians selected warfarin in the presence of a minor falls risk and 17.1% would anticoagulate if the patient had a treated peptic ulcer. Family physicians with less decisional conflict and longer-standing practices were more likely to endorse anticoagulation.

Conclusion— Strategies to optimize the management of nonvalvular atrial fibrillation should address psychological barriers to using anticoagulation.

Postoperative atrial fibrillation

Atrial fibrillation is a common arrhythmia after cardiac surgery. It is associated with an increase in morbidity, length of hospital stay, and mortality. Patients who are at higher risk of postoperative atrial fibrillation should receive prophylactic treatment. Atrial fibrillation usually resolves spontaneously after heart rate is controlled; however, if patients are highly symptomatic or hemodynamically unstable, sinus rhythm should be restored by electrical or pharmacologic cardioversion. Patients with atrial fibrillation of more than 48 hours should receive antithrombotic therapy for thromboembolism prevention.

Effectiveness of dual-source CT coronary angiography for the evaluation of coronary artery disease in patients with atrial fibrillation: initial experience

PURPOSE

To prospectively evaluate the sensitivity and specificity of dual-source CT for significant coronary stenosis (>50% narrowing) in patients with atrial fibrillation (AF), by using conventional coronary angiography as the reference standard.

MATERIALS AND METHODS

Institutional Review Board approval and informed consent were obtained. Fifteen consecutive patients (nine men, six women; mean age, 58.47 years) were examined. Image quality (good, moderate, or poor) and significant stenosis (>50%) were evaluated by two radiologists blinded to the conventional coronary angiography results. Sensitivity, specificity, positive predictive value (PPV), and negative predictive values (NPV) were calculated. McNemar test was used to search for any significant difference between dual-source CT and conventional coronary angiography in helping detect coronary stenosis. kappa statistics were calculated for intermodality and interobserver agreement.

RESULTS

Sixteen segments by reader 1 and 13 segments by reader 2 were considered as poor image quality and rejected for further analysis. All segments with good image quality were correctly diagnosed. The respective overall sensitivity, specificity, PPV, and NPV values were 87%, 98%, 77%, and 99% for reader 1 and 80%, 99%, 80%, and 99% for reader 2. No significant difference between dual-source CT and conventional coronary angiography was found in helping detect significant stenosis. kappa statistics demonstrated good intermodality and excellent interobserver agreement.

CONCLUSION

Dual-source CT technology provides a temporal resolution that allows CT coronary angiography at higher heart rates and even with AF.

Left atrial appendage filling defects identified by multidetector computed tomography in patients undergoing radiofrequency pulmonary vein antral isolation: a comparison with transesophageal echocardiography

BACKGROUND

Patients referred for radiofrequency pulmonary vein antral isolation undergo contrast-enhanced multidetector computed tomography (MDCT) to assess pulmonary vein and left atrial anatomy as well as transesophageal echocardiography (TEE) to detect intraatrial thrombus. We sought to determine the accuracy of MDCT to qualitatively and quantitatively detect severe spontaneous echo contrast (SEC) or thrombus by TEE in the left atrial appendage (LAA).

METHODS

Two hundred twenty-three consecutive MDCT and TEE studies performed within 7 days of each other were retrospectively identified. The LAA was evaluated by MDCT for filling defects and by TEE for thrombus or SEC. Severe SEC or thrombus on TEE was considered positive. In patients with preserved ejection fraction, the Hounsfield unit (HU) density of a 1-cm2 region of interest was measured in the LAA and ascending aorta (AA) of the same slice to calculate an LAA/AA HU ratio.

RESULTS

Visually identified filling defects in LAA by MDCT correspond to severe SEC and thrombus with a sensitivity, specificity, positive predictive value, and negative predictive value of 93%, 85%, 31%, and 99%, respectively. Multidetector CT missed severe SEC detected by TEE in one examination; all thrombi, however, were correctly identified. There is a significant inverse association between mean LAA/AA HU ratios with increasing grades of SEC or thrombus (P < .001). Using an LAA/AA HU ratio cutoff of 0.25, the positive predictive value and specificity increased to 75% and 96%, respectively, while preserving a high negative predictive value (96%).

CONCLUSIONS

Multidetector CT can qualitatively and quantitatively identify and distinguish severe LAA SEC/thrombus from lesser grades of SEC.

New antiarrhythmic drugs for establishing sinus rhythm in atrial fibrillation: what are our therapies likely to be by 2010 and beyond?

The management of atrial fibrillation (AF) is plagued by, among other things, limitations in the efficacy, tolerance, and safety of currently available agents for the conversion of AF to sinus rhythm and for the maintenance of sinus rhythm. This review describes some of the most promising approaches to new therapies that may overcome some of the limitations of our current therapies. The agents we have chosen to review are representative of these new approaches and have completed their phase III trials and have submitted an application for approval for release by regulatory agencies or have almost completed their phase III trials and appear likely to submit for approval in the not to distant future.

Outpatient use of anticoagulants, rate-controlling drugs, and antiarrhythmic drugs for atrial fibrillation

BACKGROUND

The first clinical practice guidelines for management of atrial fibrillation (AF) were published in 2001. We explored the use of anticoagulants, rate-controlling drugs, and antiarrhythmic drugs in patients with AF during the 4 years surrounding publication of these guidelines.

METHODS

Mentions of warfarin, beta-blockers, digoxin, diltiazem, verapamil, and all class I and class III antiarrhythmic drugs made by US office-based physicians during patient visits for AF between October 1999 and September 2003 were evaluated using the IMS Health National Disease and Therapeutic Index (Plymouth Meeting, PA). Medication use by patient age, sex, and physician specialty was explored. Trends in use during the study period were estimated.

RESULTS

Warfarin was mentioned in an average of 37% of all AF-related visits across the observation period, with no statistically significant change over time. Digoxin was the most commonly mentioned rate-controlling drug in 23% of patient visits, followed by beta-blockers in 11% and calcium-channel blockers in 8%. Over the study period, mentions of digoxin significantly decreased, and mentions of beta-blockers significantly increased. Mentions of antiarrhythmic drugs were reported in an average of 12% of patient visits, with no significant change over the study period.

CONCLUSIONS

Observed trends in use of digoxin, beta-blockers, and class Ia antiarrhythmic drugs were consistent with evidence-based recommendations. However, only approximately one third of patient visits for AF included mentions of warfarin, even among patients aged > or = 60 years. These results indicate the need for continued education and interventions, especially regarding stroke prevention, in patients with AF.

Antiarrhythmics for maintaining sinus rhythm after cardioversion of atrial fibrillation

BACKGROUND

Atrial fibrillation (AF) is the most frequent sustained arrhythmia. After restoration of normal sinus rhythm, the recurrence rate of AF is high. Antiarrhythmic drugs have been widely used to prevent recurrence, but the effect of these drugs on mortality and other clinical outcomes is unclear.

OBJECTIVES

To determine, in patients who recovered sinus rhythm after AF, the effect of long-term treatment with antiarrhythmic drugs on death, stroke and embolism, adverse effects, pro-arrhythmia and recurrence of AF. If several antiarrhythmics were effective our secondary aim was to compare them.

SEARCH STRATEGY

The Cochrane Central Register of Controlled Trials (CENTRAL) on The Cochrane Libary (Issue 2, 2005), MEDLINE (1950 to May 2005) and EMBASE (1966 to May 2005) were searched. The reference lists of retrieved articles, recent reviews and meta-analyses were checked. No language restrictions were applied.

SELECTION CRITERIA

Two independent reviewers selected randomised controlled trials comparing any antiarrhythmic with a control (no treatment, placebo or drugs for rate control) or with another antiarrhythmic, in adults who had AF and in whom sinus rhythm was restored. Post-operative AF was excluded.

DATA COLLECTION AND ANALYSIS

Two reviewers independently assessed quality and extracted data, on an intention-to-treat basis. Disagreements were resolved by discussion. Studies were pooled, if appropriate, using Peto odds ratio (OR).

MAIN RESULTS

45 studies met inclusion criteria, comprising 12,559 patients. All results were calculated at 1 year of follow-up. Class IA drugs (disopyramide, quinidine) were associated with increased mortality compared with controls (OR 2.39, 95% confidence interval (CI) 1.03 to 5.59, P = 0.04, number needed to harm (NNH) 109, 95% CI 34 to 4985). Other antiarrhythmics did not modify mortality. Several class IA (disopyramide, quinidine), IC (flecainide, propafenone) and III (amiodarone, dofetilide, dronedarone, sotalol) drugs significantly reduced recurrence of AF (OR 0.19 to 0.60, number needed to treat 2 to 9), but all increased withdrawals due to adverse affects (NNH 17 to 36) and all but amiodarone and propafenone increased pro-arrhythmia (NNH 17 to 119).

AUTHORS' CONCLUSIONS

Several class IA, IC and III drugs are effective in maintaining sinus rhythm but increase adverse events, including pro-arrhythmia, and disopyramide and quinidine are associated with increased mortality. Any benefit on clinically relevant outcomes (embolisms, heart failure, mortality) remains to be established.

Atrial fibrillation in haemodialysis patients: Do the guidelines for anticoagulation apply?

AIM

Atrial fibrillation (AF) is common in haemodialysis patients, but the risks and benefits of anticoagulation in this group are not well characterized. We investigated the prevalence of AF, its associated risk factors, and the incidence of stroke and haemorrhage in a cohort of haemodialysis patients.

METHODS

We retrospectively reviewed 155 patients undergoing maintenance haemodialysis on 1 April 2003 (age 56.9 +/- 13.5 years; men 62.6%; mean duration of haemodialysis 39.3 +/- 37.5 months). Patients with paroxysmal or permanent AF were identified, and baseline clinical and echocardiographic data were obtained. The incidence of cerebrovascular accidents, major haemorrhage and all-cause mortality was assessed during the 26 month average follow-up period.

RESULTS

AF was present in 25.8% of patients, paroxysmal in 18.1%, and permanent in 7.7%. Patients with AF were more likely to be older (64.2 +/- 9.4 vs 54.4 +/- 13.8 years; P < 0.005), have underlying ischaemic heart disease or congestive heart failure, and have a lower serum albumin (P < 0.05 for all). Only 12.5% of AF patients were anticoagulated, although 47.5% had contraindications to warfarin. Cerebrovascular events occurred in 5.2% of all patients (30.4 episodes/1000 patient-years), and major haemorrhage in 20.0% (106.4 episodes/1000 patient-years). All-cause mortality was 29.7%. The endpoints for the AF group did not significantly differ from the non-AF group.

CONCLUSION

AF is common in haemodialysis patients. The incidence of major haemorrhage was over three times that of cerebrovascular accidents. Guideline recommendations for anticoagulation in AF in the general population may not be appropriate for the haemodialysis population.

Early complications of pulmonary vein catheter ablation for atrial fibrillation: A multicenter prospective registry on procedural safety

BACKGROUND

Data on the procedural safety of pulmonary vein radiofrequency catheter ablation for atrial fibrillation (AF) are as yet scant.

OBJECTIVE

The aims of the present study were to prospectively evaluate the incidence of early complications of pulmonary vein ablation for AF in an unselected population of consecutive patients, and to identify possible predictors.

METHODS

From April 2005 to October 2006, data from 1,011 consecutive patients who were undergoing radiofrequency catheter ablation for every type of AF in 10 Italian centers were collected. All complications occurring from the admission of the patient up to the 30th day were considered.

RESULTS

No procedure-related death was observed. Complications occurred in 40 patients (3.9%): 12 (1.2%) had peripheral vascular complications, 8 (0.8%) had conservatively treated pericardial effusion, 6 (0.6%) had cardiac tamponade (successfully drained), 5 (0.5%) had cerebral embolisms, 4 (0.4%) presented pulmonary vein stenosis >50%, and 5 (0.5%) presented other isolated adverse events. History of coronary artery disease (odds ratio 5,603, 95% confidence interval 1,559 to 20,139, P < .008) characterized patients who presented with hemorrhagic complications.

CONCLUSION

Early complications of pulmonary vein catheter ablation seem to be fewer than in the early years of AF ablation, but still occur in 3.9% of procedures.

The molecular basis of high-affinity binding of the antiarrhythmic compound vernakalant (RSD1235) to Kv1.5 channels

Vernakalant (RSD1235) is an investigational drug recently shown to convert atrial fibrillation rapidly and safely in patients (J Am Coll Cardiol 44:2355-2361, 2004). Here, the molecular mechanisms of interaction of vernakalant with the inner pore of the Kv1.5 channel are compared with those of the class IC agent flecainide. Initial experiments showed that vernakalant blocks activated channels and vacates the inner vestibule as the channel closes, and thus mutations were made, targeting residues at the base of the selectivity filter and in S6, by drawing on studies of other Kv1.5-selective blocking agents. Block by vernakalant or flecainide of Kv1.5 wild type and mutants was assessed by whole-cell patch-clamp experiments in transiently transfected human embryonic kidney 293 cells. The mutational scan identified several highly conserved amino acids, Thr479, Thr480, Ile502, Val505, and Val508, as important residues for affecting block by both compounds. In general, mutations in S6 increased the IC50 for block by vernakalant; I502A caused an extremely local 25-fold decrease in potency. Specific changes in the voltage-dependence of block with I502A supported the crucial role of this position. A homology model of the pore region of Kv1.5 predicted that, of these residues, only Thr479, Thr480, Val505, and Val508 are potentially accessible for direct interaction, and that mutation at additional sites studied may therefore affect block through allosteric mechanisms. For some of the mutations, the direction of changes in IC50 were opposite for vernakalant and flecainide, highlighting differences in the forces that drive drug-channel interactions.

Optimal β-blocker for prevention of atrial fibrillation after on-pump coronary artery bypass graft surgery: Carvedilol versus metoprolol

BACKGROUND

Atrial fibrillation (AF) is the most common arrhythmia after coronary artery bypass graft (CABG) surgery. It has been shown that prophylactic oral beta-blocker administration reduces the incidence of post-CABG AF. However, the optimal beta-blocker has not been identified.

OBJECTIVE

This study sought to determine whether oral carvedilol (with its unique anti-inflammatory and antioxidant properties) is more effective than oral metoprolol for prevention of AF after CABG surgery.

METHODS

Between April 2006 and December 2006, 120 patients (63 men, mean age 61 +/- 9.4 years) who were scheduled to undergo their first on-pump CABG were enrolled in this study. The patients were randomized in a prospective 1:1 manner to receive either oral carvedilol (n = 60) or oral metoprolol (n = 60). The end point of the study was the occurrence of the new-onset AF during the first 5 days after CABG.

RESULTS

AF occurred in 29 of 120 patients (24.0%). The incidence of postoperative AF was 15.0% (9 of 60) in the carvedilol group and 33% (20 of 60) in the metoprolol group (P = .022). The carvedilol group was treated with mean daily dose of 46 +/- 9 mg and metoprolol group with mean daily dose of 93 +/- 11 mg. There were no differences between the study groups regarding any known preoperative, perioperative, or postoperative characteristics (all values were P >.05). No significant adverse effect was observed in either group.

CONCLUSION

This prospective study suggested that oral carvedilol is more effective than oral metoprolol in the prevention of AF after on-pump CABG. It is well tolerated when started before and continued after the surgery. However, further prospective studies are needed to clarify this issue.

Cost Comparison of Catheter Ablation and Medical Therapy in Atrial Fibrillation

INTRODUCTION

There is emerging evidence for clinical superiority of catheter ablation over rate and rhythm control strategies in paroxysmal atrial fibrillation (PAF). The objective of this study was to compare costs related to medical therapy versus catheter ablation for PAF in Ontario (Canada).

METHODS

Costs related to medical therapy in the analysis included the cost of anticoagulation, rate and rhythm control medications, noninvasive testing, physician follow-up visits, and hospital admissions, as well as the cost of complications related to this management strategy. Costs related to catheter ablation were assumed to include the cost of the ablation tools (electroanatomic mapping or intracardiac echocardiography-guided pulmonary vein ablation), hospital and physician billings, and costs related to periprocedural medical care and complications. Costs related to these various elements were obtained from the Canadian Registry of Atrial Fibrillation (CARAF), government fee schedules, and published data. Sensitivity analyses looking at a range of initial success rates (50-75%) and late attrition rates (1-5%), prevalence of congestive heart failure (CHF) (20-60%), as well as discounting varying from 3% to 5% per year were performed.

RESULTS

The cost of catheter ablation ranged from $16,278 to $21,294, with an annual cost of $1,597 to $2,132. The annual cost of medical therapy ranged from $4,176 to $5,060. Costs of ongoing medical therapy and catheter ablation for PAF equalized at 3.2-8.4 years of follow-up.

CONCLUSION

Catheter ablation is a fiscally sensible alternative to medical therapy in PAF with cost equivalence after 4 years.

Atrial fibrillation and congestive heart failure: a two-way street

Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia encountered in clinical cardiology, particularly in patients with heart failure. Its prevalence increases with the degree of left ventricular dysfunction and severity of heart failure symptoms. The development of AF in the setting of heart failure has been shown to result in increased mortality. Studies thus far indicate that rhythm control with antiarrhythmic drug therapy or catheter ablation offers both symptomatic and probably survival advantage in patients with heart failure and AF. In patients with permanent AF, the effects of restoring a regular ventricular response with atrioventricular junction ablation followed by biventricular pacing remain to be shown. In the current manuscript, we will review the proposed mechanisms of increased morbidity and mortality associated with AF and the current treatment options including the roles of radiofrequency ablation and pacing.

Beat shock proteins and atrial fibrillation

In this mini-review, the role of heat shock proteins in susceptability to induction of atrial fibrillation (AF) or in the process of AF is discussed. AF is the most common arrhythmia in humans, is self-perpetuating in nature and hence tends to become more persistent in time. Some studies show a correlation between high Hsp70 (HspA1A) expression in cardiac tissue and a reduced susceptability to induction of postoperative AF. Expression of Hsp70, Hsc70 (HspA8), Hsp40 (DnaJB1), Hsp60 (HspD1), Hsp90 (HspC1) was not associated with progression of AF. However, both correlative studies in human and experimental studies suggest that Hsp27 (HspB1) may delay progression of AF to the more permanent forms and hence Hsp27 might be referred to as a "Beat shock protein".

Age-related changes in P wave morphology in healthy subjects

Background

We have previously documented significant differences in orthogonal P wave morphology between patients with and without paroxysmal atrial fibrillation (PAF). However, there exists little data concerning normal P wave morphology. This study was aimed at exploring orthogonal P wave morphology and its variations in healthy subjects.

Methods

120 healthy volunteers were included, evenly distributed in decades from 20–80 years of age; 60 men (age 50+/-17) and 60 women (50+/-16). Six-minute long 12-lead ECG registrations were acquired and transformed into orthogonal leads. Using a previously described P wave triggered P wave signal averaging method we were able to compare similarities and differences in P wave morphologies.

Results

Orthogonal P wave morphology in healthy individuals was predominately positive in Leads X and Y. In Lead Z, one third had negative morphology and two-thirds a biphasic one with a transition from negative to positive. The latter P wave morphology type was significantly more common after the age of 50 (P < 0.01). P wave duration (PWD) increased with age being slightly longer in subjects older than 50 (121+/-13 ms vs. 128+/-12 ms, P < 0.005). Minimal intraindividual variation of P wave morphology was observed.

Conclusion

Changes of signal averaged orthogonal P wave morphology (biphasic signal in Lead Z), earlier reported in PAF patients, are common in healthy subjects and appear predominantly after the age of 50. Subtle age-related prolongation of PWD is unlikely to be sufficient as a sole explanation of this finding that is thought to represent interatrial conduction disturbances. To serve as future reference, P wave morphology parameters of the healthy subjects are provided.

Role of Rac1 GTPase activation in atrial fibrillation

OBJECTIVES

We aimed to study the role of Rac1 GTPase in atrial fibrillation (AF).

BACKGROUND

The signal transduction associated with AF is incompletely understood. We hypothesized that activation of Rac1 GTPase contributes to the pathogenesis of AF via activation of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase and production of reactive oxygen species.

METHODS

Old mice with cardiac-specific overexpression of constitutively active V12Rac1 (RacET) were compared with wild-type (WT) and WT undergoing transaortic constriction (TAC). In addition, samples of human left atrial appendages were analyzed in patients with sinus rhythm (SR) compared with patients with permanent AF matched for atrial diameter.

RESULTS

At age 16 months, 75% of RacET but no WT or TAC mice showed AF. Treatment of RacET with statins for 10 months did not alter weight or fibrosis of atria or ventricles but decreased cardiac Rac1 and NADPH oxidase activity and reduced the incidence of AF by 50%. The left atria of patients with AF showed increased fibrosis, up-regulation of NADPH oxidase activity, a 4-fold increase of Rac1 total protein and membrane expression as well as up-regulation of Rac1 activity.

CONCLUSIONS

Chronic cardiac overexpression of Rac1 represents a novel mouse model for AF. Rac1 GTPase contributes to the pathogenesis of AF and identifies a target for the prevention and treatment of AF.

Single-step atrial thrombus exclusion and transesophageal cardioversion in atrial fibrillation

Atrial fibrillation (AF), the most common arrhythmia, has a major impact on both patient morbidity and healthcare economics. Hospital admissions due to AF have risen by two-thirds in the last 20 years. This is due mainly to an aging population and an increasing prevalence of chronic heart disease. Strategies for the management of AF include prevention of thromboembolism, rate control and correction of the arrhythmia. Electrical cardioversion as one component of the treatment of AF requires the absence of atrial thrombi. Transesophageal echocardiography is used routinely for exclusion of atrial thrombi prior to cardioversion in many hospitals. This review presents preliminary data on the clinical use of devices for simultaneous transesophageal echocardiography and transesophageal cardioversion.

Ablation should not be first-line therapy for the treatment of atrial fibrillation

The introduction of new techniques into medical practice frequently results in uncertainty for potential referring physicians and patients alike. The development of safe and effective percutaneous techniques for the cure of symptomatic Wolff-Parkinson-White (WPW) syndrome quickly led to near-elimination of the use of cardiac surgery and antiarrhythmic drugs to treat this proarrhythmic condition, and is justly regarded as a triumph of innovation by both electrophysiologists and biomedical engineers. The introduction of balloon angioplasty also led to a reduction in the number of patients referred for surgical procedures, although with arguably less rationale. An excess of popular enthusiasm among patients and physicians for this procedure made critical debate (continuing in academic circles) moot, at least in the USA. In this paper, I will argue that radiofrequency ablation for the treatment of atrial fibrillation is more akin to the use of angioplasty and less like the treatment of WPW, and cannot be justified as first-line therapy. Unfortunately, excessively optimistic characterization of ablation for atrial fibrillation is obscuring critical issues that ought to be considered by electrophysiologists, referring physicians and patients.

Catheter ablation as first-line therapy for patients with symptomatic atrial fibrillation

Atrial fibrillation (AF) is a common clinical problem that is associated with an impaired quality of life, thromboembolism, heart failure and death. Medical treatment of AF remains suboptimal and is associated with potentially serious side effects. The disappointing outcomes with medical therapy have spurred the age of catheter ablation of AF. In the last 10 years, catheter ablation of AF has evolved dramatically and has been shown to be superior to medical therapy in multiple studies. As a result, catheter ablation may be offered to the symptomatic patient as first-line therapy in lieu of antiarrhythmic medications, which have limited efficacy and are associated with significant toxicity.

National underuse of anti-thrombotic therapy in chronic atrial fibrillation identified from digoxin prescribing

AIMS

To examine if appropriate antithrombotic therapy in atrial fibrillation is implemented nationally.

METHODS

Using prescriptions for digoxin as a surrogate for atrial fibrillation, we identified its coprescription with antithrombotic therapy, aspirin or warfarin in a national prescribing database in 27 571 patients over 45 years old.

RESULTS

Proportionately significantly more men were on warfarin, and use in those >75 years old was three times less than in those <65 years. Reluctance to use antithrombotics was confirmed in a postal survey.

CONCLUSION

Data suggest a missed opportunity to prevent stroke with women and those >75 years old least likely to receive warfarin.

Atrial fibrillation in the elderly

Atrial fibrillation is increasingly prevalent among older adults. It causes approximately 24% of strokes in patients aged 80 to 89 years. The management of atrial fibrillation is directed at preventing thromboembolism and controlling the heart rate and rhythm. Stroke prevention is most effectively accomplished through administering anticoagulants such as warfarin, although older patients have higher hemorrhagic risk. Cognitive dysfunction, functional impairments, and increased fall risk further complicate warfarin management in elderly patients. The use of risk stratification schemes can help guide the anticoagulation decision, although the benefits of warfarin generally outweigh the risks in most older patients with atrial fibrillation. Pharmacologic rate control has been shown to result in similar outcomes compared with pharmacologic restoration of sinus rhythm and should be the initial therapy for elderly patients. Anti-arrhythmic medications should be selected based on an individual patient's coexisting medical conditions. In symptomatic patients who fail pharmacologic therapy, invasive strategies such as AV nodal ablation may help improve quality of life and symptoms, although such strategies do not obviate the need for antithrombotic therapy.

Major Hemorrhage and Tolerability of Warfarin in the First Year of Therapy Among Elderly Patients With Atrial Fibrillation

Background— Warfarin is effective in the prevention of stroke in atrial fibrillation but is under used in clinical care. Concerns exist that published rates of hemorrhage may not reflect real-world practice. Few patients ≥80 years of age were enrolled in trials, and studies of prevalent use largely reflect a warfarin-tolerant subset. We sought to define the tolerability of warfarin among an elderly inception cohort with atrial fibrillation.

Methods and Results— Consecutive patients who started warfarin were identified from January 2001 to June 2003 and followed for 1 year. Patients had to be ≥65 years of age, have established care at the study institution, and have their warfarin managed on-site. Outcomes included major hemorrhage, time to termination of warfarin, and reason for discontinuation. Of 472 patients, 32% were ≥80 years of age, and 91% had ≥1 stroke risk factor. The cumulative incidence of major hemorrhage for patients ≥80 years of age was 13.1 per 100 person-years and 4.7 for those <80 years of age ( P =0.009). The first 90 days of warfarin, age ≥80 years, and international normalized ratio (INR) ≥4.0 were associated with increased risk despite trial-level anticoagulation control. Within the first year, 26% of patients ≥80 years of age stopped taking warfarin. Perceived safety issues accounted for 81% of them. Rates of major hemorrhage and warfarin termination were highest among patients with CHADS 2 scores (an acronym for congestive heart failure, hypertension, age ≥75, diabetes mellitus, and prior stroke or transient ischemic attack) of ≥3.

Conclusions— Rates of hemorrhage derived from younger noninception cohorts underestimate the bleeding that occurs in practice. This finding coupled with the short-term tolerability of warfarin likely contributes to its underutilization. Stroke prevention among elderly patients with atrial fibrillation remains a challenging and pressing health concern.

Sealing the left atrial appendage: ready for prime time?

Atrial fibrillation (AF) is the most common sustained arrhythmia and a leading cause of stroke. Warfarin reduces the incidence of thromboemboli and is recommended for most patients with AF. However, oral anticoagulation is contraindicated or not tolerated by a significant percentage of patients with AF. Occlusion of the left atrial appendage, the major source of emboli in atrial fibrillation, has been shown to be a potential alternative to warfarin in patients with AF who have contraindications to anticoagulation. In this article, we describe the current percutaneous left atrial appendage occlusion devices, their safety in recent trials, and their potential role in stroke prevention in AF.

Relation of C-reactive protein to long-term risk of recurrence of atrial fibrillation after electrical cardioversion

The aim of this study is to assess the role of C-reactive protein (CRP) in predicting long-term risk of atrial fibrillation (AF) recurrence after electrical cardioversion. CRP levels are associated with the presence of AF and failure of electrical or pharmacologic cardioversion, but no previous study has assessed their predictive role in long-term follow-up after successful electrical cardioversion. One hundred two consecutive patients (age 67 +/- 11 years; 58 men) with nonvalvular persistent AF who underwent successful biphasic electrical cardioversion were studied. High-sensitivity CRP was measured immediately before cardioversion. Follow-up was performed up to 1 year in all cases. Patients were divided into 4 groups according to CRP quartiles. Patients in the lowest CRP quartile (<1.9 mg/L) had significantly lower rates of AF recurrence (4% vs 33% at 3 months in the other 3 groups combined, p = 0.007, and 28% vs 60% at 1 year, p = 0.01). The 4 groups were similar in age, gender, ejection fraction, and left atrial size. Survival analysis confirmed that patients in the lowest CRP quartile had a lower recurrence rate (p = 0.02). Cox regression analyses using age, gender, hypertension, diabetes, ejection fraction, left atrial diameter, use of antiarrhythmic drugs, angiotensin-converting enzyme inhibitors or angiotensin II antagonists, and statins, and CRP quartiles as covariates showed that only CRP was independently associated with AF recurrence during follow-up (hazard ratio 4.98, 95% confidence interval 1.75 to 14.26, p = 0.003). In conclusion, low CRP is associated with long-term maintenance of sinus rhythm after cardioversion for nonvalvular AF.