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PubMed2002

Use of beta-blockers in atrial fibrillation.

Atrial fibrillation is the most common arrhythmia in the general population and is frequently associated with organic heart disease. beta-adrenoceptor antagonists (b-blockers) are very effective in preventing atrial fibrillation after coronary artery bypass surgery. It has been shown recently that the beta-blocker metoprolol controlled release/extended release (CR/XL) is also effective in maintaining sinus rhythm after conversion of atrial fibrillation. There is concern that class I antiarrhythmic drugs, such as quinidine, disopyramide, and flecainide in particular, may increase mortality. The risk of proarrhythmia associated with beta-blocker treatment is very low. Therefore b-blockers, such as metoprolol CR/XL, may be the first line of treatment to maintain sinus rhythm, especially after myocardial infarction and in patients with chronic heart failure and in those with arterial hypertension. In patients with persistent atrial fibrillation, AV-nodal conduction-slowing drugs, such as calcium channel antagonists and beta-blockers are used to control the ventricular rate during atrial fibrillation. Several studies clearly show that beta-blockers alone, or in combination with digoxin are very effective in controlling the ventricular rate at rest and during exercise. beta-blockers are effective in maintaining sinus rhythm and controlling the ventricular rate during atrial fibrillation. Given these effects and their favorable effects on mortality, beta-blockers should be considered as first-line agents in the management of patients with atrial fibrillation.

Adrenergic beta-Antagonists↗
PubMed1999

[Pathology of atrial fibrillation].

Atrial fibrillation is one of the most common arrhythmias which is associated with various organic heart diseases or systemic disorders. Although a pathological basis for atrial fibrillation has not been clarified, an anatomical substrate corresponding to long-term atrial fibrillation has been recently demonstrated. Age-related changes of the atrial myocardium were frequently observed in healthy people. Quantitative histological study of the sinoatrial node revealed no difference in the reduction of the nodal cells between 12 patients with atrial fibrillation and 21 age-matched controls. The pathological findings of the myocardium including atrial preferential pathways in patients with long-term atrial fibrillation showed depletion of the muscular bundles, fibrosis and fatty metamorphosis of the atrial myocytes. These findings suggest that atrial fibrillation might be related to reentry in the residual muscular bundles including circumferential muscular bundles in the right atrium.

Aged↗
PubMed1991

Operations for atrial fibrillation.

Atrial fibrillation is the most common of all sustained cardiac arrhythmias, yet it has no effective medical or surgical therapy. During the past decade, multipoint computerized electrophysiological mapping systems were used to map both experimental and human atrial fibrillation. On the basis of these studies, a new surgical procedure was developed for atrial fibrillation. Between September 25, 1987, and May 1, 1991, this procedure was applied in 22 patients with either paroxysmal atrial flutter (n = 2), paroxysmal atrial fibrillation (n = 11), or chronic atrial fibrillation (n = 9) of 2 to 21 years' duration. All patients were refractory to all antiarrhythmic medications and each patient failed an average of 5.2 drugs preoperatively. There were no operative deaths and all perioperative morbidity resolved. All 22 patients have been cured of atrial fibrillation with surgery alone. One late isolated episode of atrial flutter occurred in a patient who is now receiving encainide. Preservation of atrial transport function has been documented in all of the patients postoperatively and all have experienced marked clinical improvement.

Adult↗
PubMed1998

The peri-operative management of atrial fibrillation.

Atrial fibrillation is a common arrhythmia frequently seen in surgical patients. The onset of new atrial fibrillation during the peri-operative period is less common. There are many possible precipitating factors, although volatile agents themselves may have an antifibrillatory action. The management of atrial fibrillation includes removal of any precipitating factors and treatment of the arrhythmia itself. Immediate management of acute-onset atrial fibrillation is usually direct current cardioversion. Alternatively, anti-arrhythmic drugs can be used to achieve cardioversion. In patients with rapid, chronic atrial fibrillation or those refractory to cardioversion, priority is given to control of the ventricular rate. Thrombo-embolism is a significant risk if atrial fibrillation is paroxysmal or persists for more than 48 h.

Anti-Arrhythmia Agents↗
PubMed2003

Emergency management of atrial fibrillation.

Atrial fibrillation is the most common cardiac arrhythmia managed by emergency and acute general physicians. There is increasing evidence that selected patients with acute atrial fibrillation can be safely managed in the emergency department without the need for hospital admission. Meanwhile, there is significant variation in the current emergency management of acute atrial fibrillation. This review discusses evidence based emergency management of atrial fibrillation. The principles of emergency management of acute atrial fibrillation and the subset of patients who may not need hospital admission are reviewed. Finally, the need for evidence based guidelines before emergency department based clinical pathways for the management of acute atrial fibrillation becomes routine clinical practice is highlighted.

Ambulatory Care↗
PubMed1993

Surgical therapy for atrial fibrillation.

Atrial fibrillation is the most common sustained rhythm other than sinus rhythm encountered in clinical practice. There are three detrimental sequelae to the rhythm of atrial fibrillation, although the relative magnitude of the detriment varies from patient to patient. These include the sensation of the irregular heart beat, the hemodynamic compromise that is associated with the loss of atrial transport function, and the third is the risk of thromboembolism. Twelve years of experimental and clinical investigation have resulted in the development of a surgical procedure to cure patients with both paroxysmal and chronic atrial fibrillation, as well as atrial flutter. The operation is successful in restoring all patients to sinus rhythm, restoring atrial transport function, and in preventing the recurrence of atrial fibrillation. This procedure is becoming the treatment of choice in patients with drug-refractory, symptomatic atrial fibrillation.

Adult↗
PubMed1997

Potential role of 'hybrid therapy' for atrial fibrillation.

Atrial fibrillation is the most common sustained arrhythmia in clinical practice. Several new non-pharmacological technologies are emerging which may offer hope for effective therapy and quality of life improvement of patients with atrial fibrillation. While both catheter-based atrial segmentation and implanted atrial defibrillators have the potential to revolutionize the treatment of patients with atrial fibrillation, both are also associated with the potential for significant limitations. Catheter ablation with the goal of curing atrial fibrillation may be a lengthy procedure and if left atrial lesions are required there is the potential for complications. As regards implanted atrial defibrillators an important question is whether many patients will tolerate the discomfort associated with energy levels required to restore sinus rhythm. The concept of 'hybrid therapy' is that in a given patient a combination of modalities might be used so as to achieve a synergistic effect, with each technology improving the efficacy of the other. For example, the presence of a more 'organized' pattern of fibrillation implies a lower defibrillation threshold. Data in a canine model of atrial fibrillation suggests that linear lesions in the right atrium alone may organize the atrial fibrillation in both atria and in so doing lower the atrial defibrillation threshold. Hybrid therapy may also employ drugs and pacing in combination with ablative lesions and an implanted atrial defibrillator.

Animals↗
PubMed1997

Treating the non-electrical risks of atrial fibrillation.

Atrial fibrillation is a common condition and carries a risk of thromboembolism. There is general acceptance that those patients with atrial fibrillation secondary to valvular (and in particular mitral) heart disease or following valve replacement require anticoagulation. Since patients with non-valvular causes of atrial fibrillation are a more heterogeneous group, the indications for anticoagulation have been less clear. A number of benchmark studies clearly indicate that the risk of stroke can be reduced by up to 70% in those treated with warfarin, but only by a variable 30% with aspirin. Problems with interpretation of the results of these studies relate to the younger age range included and a low recruitment rate, leading to a possible under-estimate of the bleeding risk. Subgroup analysis provides risk stratification for patients with non-valvular atrial fibrillation so that those with three or more of any of the five following risk factors: congestive heart failure, hypertension, previous stroke, left atrial enlargement or left ventricular hypertrophy, have an 18% chance of new thromboembolic events, whereas this falls to one third of this with only one or two risk factors, and 1% with none. Those with so-called lone atrial fibrillation aged < 60 years have a very low incidence of atrial fibrillation and can be considered for aspirin alone. The trials supporting in these statements are presented.

Aged↗
PubMed2006

The modern surgical management of atrial fibrillation.

Atrial fibrillation is the most common arrhythmia disorder. Its incidence is especially high among patients with valvular heart disease. Patients with atrial fibrillation are at a six-fold increased risk of stroke and a two-fold increased risk of mortality. Medical management for rhythm control of patients with atrial fibrillation is suboptimal and no better than simple rate management. However, catheter-based therapies are undergoing intense development. The surgical management of atrial fibrillation has undergone considerable innovation in the last two decades; it is the subject of this review. The "cut-and-sew" Cox-maze III is considered the standard for surgical therapy for atrial fibrillation. More recently, several modifications of the Cox maze lesion set and the development of alternative energy sources to achieve transmural atrial lesions have led to a more simplified maze procedure. This simplified left-sided maze procedure has demonstrated excellent efficacy at intermediate and long-term follow-up. Therefore, the modified maze procedure should be offered to all mitral valve surgery patients and potentially to all cardiac surgery patients with a history of paroxysmal, persistent, or permanent atrial fibrillation.

Atrial Fibrillation↗
PubMed1992

Role of prophylactic anticoagulation for direct current cardioversion in patients with atrial fibrillation or atrial flutter.

The need for prophylactic anticoagulation to prevent embolism before direct current cardioversion is performed for atrial fibrillation or atrial flutter is controversial. To examine this issue further, a retrospective review was undertaken to assess the incidence of embolic complications after cardioversion. The review involved 454 elective direct current cardioversions performed for atrial fibrillation or atrial flutter over a 7 year period. The incidence rate of embolic complications was 1.32% (six patients); the complications ranged from minor visual disturbances to a fatal cerebrovascular event. All six patients had atrial fibrillation, and none had been on anticoagulant therapy (p = 0.026). The duration of atrial fibrillation was less than 1 week in five of the six patients who had embolic complications. Baseline characteristics of patients with a postcardioversion embolic event are compared with those of patients who did not have an embolic event. There was no difference in the prevalence of hypertension, diabetes mellitus or prior stroke between the two groups, and there was no difference in the number of patients who were postoperative or had poor left ventricular function. Left atrial size was similar between the two groups. No patient in the embolic group had valvular disease. No patient with atrial flutter had an embolic event regardless of anticoagulant status; therefore, anticoagulation is not recommended for patients with atrial flutter undergoing cardioversion. Prophylactic anticoagulation is pivotal in patients undergoing elective direct current cardioversion for atrial fibrillation, even those with atrial fibrillation of less than 1 week's duration.

Anticoagulants↗
PubMed2003

Present treatment options for atrial fibrillation.

Atrial fibrillation is the commonest sustained cardiac arrhythmia. It accounts for >35% of all hospital admissions for cardiac arrhythmias in the United States. The presence of atrial fibrillation increases the mortality of a population by up to twofold. The risk of stroke increases from 1.5% in patients with atrial fibrillation from 50-59 years of age to up to 23.5% for such patients aged 80-89 years. Although the diagnosis of atrial fibrillation is usually straightforward, effective treatment is not. This article will discuss how rhythm control of atrial fibrillation can best be achieved, the controversy over the rhythm versus rate control, the maintenance of sinus rhythm with antiarrhythmic drugs after cardioversion, and prevention of thromboembolism. Finally, the recent advances in various non-pharmacological approaches for the treatment of atrial fibrillation will be highlighted.

Aged↗
PubMed2000

Early cardioversion of atrial fibrillation and atrial flutter guided by transoesophageal echocardiography: a single centre 8.5-year experience.

AIMS: To analyse the safety and impact on maintenance of sinus rhythm of transoesophageal echocardiographically guided early cardioversion associated with short-term anticoagulation in a large series of patients with atrial fibrillation and atrial flutter. METHODS AND RESULTS: Patients who were candidates for cardioversion were eligible for inclusion if they had atrial fibrillation or atrial flutter lasting longer than 2 days or of unknown duration. Patients received short-term anticoagulation with warfarin or heparin and underwent transthoracic echocardiography followed by transoesophageal echocardiography. Early cardioversion was performed if no thrombus was seen on the transoesophageal study. Warfarin was maintained for 1 month after cardioversion. In patients with atrial thrombi, cardioversion was deferred and prolonged anticoagulation was prescribed. The study population included 183 patients. One hundred and sixty nine patients without atrial thrombi underwent early cardioversion. Fourteen patients with atrial thrombi (7.6%) underwent a second transoesophageal echocardiogram after a median of 4 weeks of oral warfarin, and cardioversion was performed if clot regression was documented. No patient in our study population had a clinical thromboembolic event at 1 month follow-up (95% C.I. 0-0.016). The immediate success rate of cardioversion was better among patients with atrial fibrillation < 4 weeks duration compared with patients with atrial fibrillation of longer or of unknown duration: 96.6% vs 85%, respectively (P = 0.014). At 1 month follow-up, the percentage of arrhythmia relapses in patients with initially successful cardioversion was similar in the two groups (29% vs 26%, P = ns); thus the initial better outcome in patients with recent-onset arrhythmia was not lost. CONCLUSION: Transoesophageal echocardiography-guided early cardioversion in concert with short-term anticoagulation is safe. This approach permits abbreviation of the overall duration of atrial fibrillation and has a better impact on the maintenance of sinus rhythm for patients in whom the duration of atrial fibrillation is < 4 weeks.

Adult↗
PubMed2006

[Anticoagulation with atrial fibrillation].

Atrial fibrillation is associated with a relevant risk for ischemic stroke: Observational studies suggest that one in four to five strokes is due to atrial fibrillation. Depending on the risk profile of an individual patient, the yearly risk for a stroke is between 2% and 14%. Continuous oral anticoagulation is indicated if atrial fibrillation is accompanied by at least one additional risk factor for thromboembolic complications. This recommendation is supported by several large randomized trials. Due to their low therapeutic range, vitamin K antagonists (phenprocoumon, warfarin, and others), the most commonly used oral anticoagulants, require regular anticoagulation monitoring. If well-controlled (international normalized ratio 2-3, in elderly patients preferably 2-2.5), oral anticoagulation prevents more than half of ischemic strokes related to atrial fibrillation, while bleeding complications are rare. In the follow-up of low risk patients (CHADS2-Score 0), oral anticoagulation becomes necessary when risk factors for thromboembolic complications develop. If a stroke occurs during oral anticoagulation and an INR>2 in a patient with atrial fibrillation, other causes than thromboembolic events should be considered. New anticoagulants--especially direct thrombin antagonists--are currently evaluated in clinical trials and may in the future facilitate anticoagulation in patients with atrial fibrillation.

Anti-Arrhythmia Agents↗
PubMed1996

Comparison of bipolar atrial electrogram amplitude in sinus rhythm, atrial fibrillation, and atrial flutter.

Automatic mode switching pacemakers revert to non-atrial tracking modes in response to sensed atrial tachyarrhythmias. It is unclear how atrial electrogram amplitudes in sinus rhythm compare to those during atrial tachyarrhythmias. In this study, peak-to-peak bipolar atrial electrogram amplitudes were measured during sinus rhythm and either atrial fibrillation or atrial flutter in 69 patients. The mean atrial electrogram amplitudes were 1.59 +/- 1.36 mV during sinus rhythm and 0.77 +/- 0.58 mV during atrial fibrillation (P < 0.0001) for 25 patients with atrial fibrillation and 1.81 +/- 2.07 mV during sinus and 1.5 +/- 1.81 mV (P < 0.0001) for 44 patients with atrial flutter. The mean electrogram amplitudes during both atrial fibrillation and flutter correlated significantly with amplitudes during sinus rhythm (R = 0.79, R = 0.94, respectively, both P < 0.0001). The coefficient of variance of individual electrogram amplitudes was greater in atrial fibrillation than sinus (P < 0.0001). By comparing 20th percentile electrogram amplitudes in atrial fibrillation and flutter to mean sinus amplitudes, intermittent very low electrogram amplitudes (< 0.3 mV) were more likely during atrial fibrillation and flutter if the mean sinus electrogram amplitudes were < 1.5 mV and < 0.5 mV, respectively (P < 0.01). Eightieth percentile electrogram amplitude values in atrial fibrillation and flutter were equally likely to exceed mean sinus amplitude values in respective patients. In conclusion, mean atrial electrogram amplitudes during atrial fibrillation and flutter are less than but correlated to sinus rhythm electrogram amplitudes. Very low amplitude individual electrograms during these atrial arrhythmias are associated with low mean sinus rhythm electrogram amplitudes. These findings may have implications for the programming of permanent dual chamber pacemakers in patients with paroxysmal atrial fibrillation and flutter.

Adolescent↗
PubMed2003

[Therapy of atrial fibrillation].

Atrial fibrillation is the most common cardiac arrhythmia in adults. Paroxysmal atrial fibrillation terminates spontaneously, whereas the persistent form terminates only after medical or electrical cardioversion. Permanent atrial fibrillation cannot be cardioverted. Restoration of sinus rhythm can be achieved by antiarrhythmic drugs or electrical cardioversion, both performed under continuous electrocardiographic monitoring. If atrial fibrillation has lasted longer than 48 hours or the precise time of onset cannot be determined, there are two alternative approaches: systemic anticoagulation to achieve an international normalised ratio (INR) of 2.0 to 3.0 for at least three weeks, followed by cardioversion; or cardioversion guided by transesophageal echocadiography indicating the absence of thrombus. Several drugs have been shown to be effective for the maintenance of sinus rhythm. Anticoagulant therapy is mandatory for a minimum of three weeks after cardioversion. In case of drug refractory, highly symptomatic atrial fibrillation the indication for radiofrequency catheter ablation should be discussed, although the value of this new method is still under evaluation.

Anti-Arrhythmia Agents↗
PubMed1996

Atrial reservoir and active transport function after cardioversion of chronic atrial fibrillation.

Atrial reservoir function has not been studied after successful cardioversion of chronic atrial fibrillation. Using transthoracic and transesophageal Doppler echocardiography, we measured flow velocity-time integrals of the systolic forward (Sa), diastolic forward (Da), and diastolic reversed (rAa) waves of flow velocity waveforms in the pulmonary vein and the superior vena cava, and those of the early diastolic (Ea) and late diastolic (Aa) waves of the transmitral and transtricuspid flow velocity waveforms. The left and right atrial storage fractions (LASF, RASF), indexes of atrial reservoir function, were determined as the ratios of the atrial storage volume to the ventricular stroke volume; (Sa - rAa)/(Sa - rAa + Da). The left and right atrial active contraction fractions (LAACF, RAACF), indexes of atrial active transport function, were also determined as the ratios of the atrial active contraction volume to the left ventricular stroke volume; Aa/(Ea + Aa). These indices were evaluated periodically in 12 patients with non-valvular chronic atrial fibrillation before and 1-4 days after direct current cardioversion of atrial fibrillation; in 8 of the patients, the indices were also evaluated 1-3 months after the cardioversion. An additional 10 patients in sinus rhythm served as controls. Both the LASF and RASF were low during atrial fibrillation; the values increased significantly 14 days after successful cardioversion (P < 0.01 P < 0.01), and continued to increase at 1-3 months. The LASF and RASF values 1-3 months after cardioversion were comparable to those in control subjects. Both the LAACF and RAACF also increased significantly from 1-4 days to 1-3 months after cardioversion (P < 0.05, P < 0.01), becoming comparable to those in control subjects. During the 3 months after successful cardioversion of non-valvular chronic atrial fibrillation, left and right atrial reservoir function and left and right atrial active transport function increased progressively, becoming comparable to values in the control subjects.

Aged↗
PubMed1998

Role of anticoagulant therapy in atrial fibrillation.

Atrial fibrillation belongs to the group of cardiovascular diseases that most frequently predispose to arterial thromboembolic events. Within the last years, the AFASAK, BAATAF, SPAF I, SPINAF, and CAFA trials have consistently demonstrated a significant, approximately 70%, risk reduction for stroke on oral anticoagulation in patients with nonrheumatic atrial fibrillation. This benefit by far outweighed the slight increase in annual major hemorrhage. Recently, additional trials (SPAF II, EAFT, SPAF III, and others) have shed further light on important questions concerning risk factors, secondary prophylaxis, the optimal intensity of anticoagulation, and the role of aspirin and other antiplatelet drugs. The main results of these studies are discussed in this review. The majority of patients with atrial fibrillation are > 65 years of age and have other clinical or echocardiographic risk factors. In these patients, adjusted-dose warfarin with target international normalized ratios (INRs) 2.0 to 3.0 is effective and safe. The risk of stroke rises with INR values < 2.0, whereas INR values > 3.0 result in an increase in intracerebral hemorrhages, especially in the very elderly. In contrast, no anticoagulation seems warranted in younger atrial fibrillation patients < 60 years of age without any clinical or echocardiographic risk factor. An overview of all randomized trials that compared aspirin with placebo and/or adjusted-dose warfarin indicates that adjusted-dose warfarin is approximately 50% more effective than aspirin for primary and secondary prevention of stroke, at least in patients with atrial fibrillation who have clinical risk factors. Therefore, oral anticoagulation clearly is the therapy of choice for prevention of thromboembolism in patients with atrial fibrillation.

Anticoagulants↗