Atrial Fibrillation In Setting Research Articles

Gender Differences in the Risk of Ischemic Stroke and Peripheral Embolism in Atrial Fibrillation

Previous studies provide conflicting results about whether women are at higher risk than men for thromboembolism in the setting of atrial fibrillation (AF). We examined data from a large contemporary cohort of AF patients to address this question. We prospectively studied 13,559 adults with AF and recorded data on patients' clinical characteristics and the occurrence of incident hospitalizations for ischemic stroke, peripheral embolism, and major hemorrhagic events through searching validated computerized databases and medical record review. We compared event rates by patient sex using multivariable log-linear regression, adjusting for clinical risk factors for stroke, and stratifying by warfarin use. We identified 394 ischemic stroke and peripheral embolic events during 15,494 person-years of follow-up off warfarin. After multivariable analysis, women had higher annual rates of thromboembolism off warfarin than did men (3.5% versus 1.8%; adjusted rate ratio [RR], 1.6; 95% CI, 1.3 to 1.9). There was no significant difference by sex in 30-day mortality after thromboembolism (23% for both). Warfarin use was associated with significantly lower adjusted thromboembolism rates for both women and men (RR, 0.4; 95% CI, 0.3 to 0.5; and RR, 0.6; 95% CI, 0.5 to 0.8, respectively), with similar annual rates of major hemorrhage (1.0% and 1.1%, respectively). Women are at higher risk than men for AF-related thromboembolism off warfarin. Warfarin therapy appears be as effective in women, if not more so, than in men, with similar rates of major hemorrhage. Female sex is an independent risk factor for thromboembolism and should influence the decision to use anticoagulant therapy in persons with AF.

Analysis of Current Management of Atrial Fibrillation in the Acute Setting: GEFAUR-1 Study

Limited information relative to the management of atrial fibrillation in the emergency department (ED) daily practice is available. This study evaluates current management of atrial fibrillation in this setting to identify areas for practice improvement. This was a prospective multicenter observational study carried out in 12 EDs. Adults in whom atrial fibrillation was demonstrated in an ECG obtained in the ED were included. Clinical variables and atrial fibrillation management in the ED were prospectively collected by the treating physicians using a standardized questionnaire. Patients with rapid ventricular response (>100 beats/min) were considered eligible for rate control, and patients with recent-onset episodes (<48 hours) were eligible for rhythm control. Of 1,178 patients, 41% presented with a rapid ventricular response and 21% had recent-onset episodes. Rhythm control was attempted in 42% of eligible patients, with antiarrhythmic drugs in 88% of cases (I-C drugs in 44% of patients; amiodarone in 43% of patients). Overall effectiveness of pharmacologic cardioversion was 63% (amiodarone 54.5%, flecainide 93%), whereas electrocardioversion was effective in 87.5% of cases. Rate control was performed in 68.3% of eligible patients (overall effectiveness 47.8%); digoxin was used in 67% of cases (effectiveness 45%). Both strategies were selected in 4.5% of cases, whereas no treatment for atrial fibrillation was performed in 60% of patients. In our ED population, rate-control effectiveness is poor and rhythm control is not attempted in most recent-onset episodes. Methods to improve rate-control effectiveness, the selection of patients for rhythm control, and the use of electrocardioversion appear warranted.

Anticoagulation and platelet antiaggregation therapy in stroke prevention

Purpose of review The results of recent large clinical trials have modified treatment plans formerly based on inferred mechanisms of ischemic stroke and hazards of certain forms of therapy. Recent findings Strong data have emerged to support anticoagulation with warfarin for stroke associated with inferred embolism in a setting of atrial fibrillation. No clear advantage for warfarin over aspirin exists for ischemic stroke in a setting of intracranial atheroma, patent cardiac foramen ovale, or elevated levels of antiphospholipid antibody. Among antiplatelet agents, aspirin and clopidogrel have a similar recurrent stroke risk. Combination therapies with aspirin and warfarin show no additional benefits with regard to stroke prevention and carry higher risks of hemorrhage. Treatment with aspirin combined with specially formulated long-acting dipyridamole carries a lower risk of stroke than aspirin alone and does not increase the risk of hemorrhage significantly. The combination of aspirin and clopidogrel does not reduce the risk of stroke over clopidogrel alone and carries a greater risk of bleeding than clopidogrel alone. Summary Choice of antithrombotic therapy depends on the etiology of the stroke. Oral anticoagulation treatment is the preferred choice for inferred cardioembolism in the setting of atrial fibrillation, while the varying rates of hemorrhage with oral anticoagulants continue to favor antiplatelet therapy in other settings of inferred etiology. Combinations of antithrombotic therapy vary in their lowering of stroke rate, and some raise the risk of hemorrhage. Insufficient data exist to determine whether antithrombotic therapy combined with antihypertensives, statins or other agents will further reduce the risk of stroke in synergistic or supplemental fashion, or give no additional benefit.

Anticoagulation and platelet antiaggregation therapy in stroke prevention

The results of recent large clinical trials have modified treatment plans formerly based on inferred mechanisms of ischemic stroke and hazards of certain forms of therapy. Strong data have emerged to support anticoagulation with warfarin for stroke associated with inferred embolism in a setting of atrial fibrillation. No clear advantage for warfarin over aspirin exists for ischemic stroke in a setting of intracranial atheroma, patent cardiac foramen ovale, or elevated levels of antiphospholipid antibody. Among antiplatelet agents, aspirin and clopidogrel have a similar recurrent stroke risk. Combination therapies with aspirin and warfarin show no additional benefits with regard to stroke prevention and carry higher risks of hemorrhage. Treatment with aspirin combined with specially formulated long-acting dipyridamole carries a lower risk of stroke than aspirin alone and does not increase the risk of hemorrhage significantly. The combination of aspirin and clopidogrel does not reduce the risk of stroke over clopidogrel alone and carries a greater risk of bleeding than clopidogrel alone. Choice of antithrombotic therapy depends on the etiology of the stroke. Oral anticoagulation treatment is the preferred choice for inferred cardioembolism in the setting of atrial fibrillation, while the varying rates of hemorrhage with oral anticoagulants continue to favor antiplatelet therapy in other settings of inferred etiology. Combinations of antithrombotic therapy vary in their lowering of stroke rate, and some raise the risk of hemorrhage. Insufficient data exist to determine whether antithrombotic therapy combined with antihypertensives, statins or other agents will further reduce the risk of stroke in synergistic or supplemental fashion, or give no additional benefit.

Atrial Fibrillation in Embolic Stroke: Anticoagulant Therapy at UNTH, Enugu

Objective: The decision to commence anticoagulation in a patient with embolic stroke and atrial fibrillation (AF) is often a difficult one for many clinicians. The result can have significant impact on the patient. This study was therefore undertaken to review the use of anticoagulation in embolic stroke in the setting of atrial fibrillation at the UNTH Enugu. Method: Records of patients managed for embolic stroke at the University of Nigeria Teaching Hospital Enugu in a total study period of 20 years (1980 - 1999) were retrospectively studied. Data was collected from patients' case records using a proforma that had been specifically designed for the study. Results: Twenty three patients with embolic stroke were reviewed. Nine patients had atrial fibrillation as risk factor of which six patients received anticoagulation for secondary prophylaxis of embolic stroke. A greater fraction of requiring males received anticoagulation than that in requiring females. All the patients that were anticoagulated were lost to follow-up. Conclusion: This study shows a considerable willingness in physicians to commence anticoagulation in the setting of embolic stroke with concurrent atrial fibrillation. Efforts should be made to enhance physician confidence and attitude towards appropriate anticoagulation where required. Measures to encourage adequate follow-up of patients are required. Key Words: Atrial fibrillation, embolic stroke, anticoagulation Orient Journal of Medicine Vol.16(3&4) 2004: 14-17

Heart failure with preserved systolic function

At least 30% of patients with congestive heart failure have preserved systolic function in the absence of significant valvular heart disease. These patients have diastolic dysfunction. Patients are frequently older and hypertensive. The rate of hospitalization in these patients is similar to that in patients with systolic dysfunction. Mortality is intermediate between that of patients with systolic dysfunction heart failure and normal subjects. Diagnosis requires a clear demonstration of the presence of the heart failure syndrome, normal systolic function, and the absence of valvular disease that could increase left atrial pressures. The diagnosis is supported by evidence of diastolic dysfunction that, from a practical point of view, will be provided most frequently by tissue Doppler imaging. Few randomized data are available on efficacy of therapeutic approaches. Acute treatment centers on reducing central blood volume with diuretics and nitrates and controlling heart rate, particularly in the setting of atrial fibrillation. Further treatment centers on reversing underlying pathophysiologic changes, particularly left ventricular hypertrophy. Control of hypertension and antagonism of the renin-angiotensin-aldosterone system appear to be promising therapeutic approaches.

Ximelagatran: a new oral anticoagulant.

Although there have been many significant advances over the last 50 years with regards to anticoagulant therapy, warfarin remains the definitive standard for the long-term prevention of thromboembolic events in many patients at risk for these complications. Although effective, warfarin has a narrow therapeutic window, necessitating frequent laboratory monitoring for anticoagulant effect. Ximelagatran is an investigational anticoagulant that directly inhibits thrombin, unlike heparin or warfarin, which are indirect inhibitors. Although indirect thrombin inhibitors are mainly only effective at inhibiting circulating thrombin, direct thrombin inhibitors are able to inhibit both free and clot-bound thrombin, thereby producing more effective anticoagulation. Ximelagatran is the first orally available direct thrombin inhibitor to reach phase 3 clinical trials. Ximelagatran is a prodrug for the active metabolite melagatran, and has been demonstrated to have a relatively wide therapeutic window in terms of bleeding and antithrombotic effect compared with warfarin. Clinical studies have demonstrated ximelagatran to be comparable in efficacy to warfarin and low-molecular-weight heparins (LMWH) for prophylaxis of venous thromboembolism, comparable to warfarin for stroke prevention in the setting of atrial fibrillation, and, when combined with aspirin, possible more effective than aspirin alone at preventing major adverse cardiovascular events in patients with a recent myocardial infarction. Adverse effects with ximelagatran primarily involve bleeding complications, which are more frequent than with placebo, but appear comparable to those occurring with standard anticoagulant treatment (ie, warfarin and LMWH). Ximelagatran has also been demonstrated to cause transient increases in liver enzymes, the significance of which will need to be addressed in ongoing phase 3 studies. Should ongoing trials prove ximelagatran to have at least similar therapeutic efficacy and safety as warfarin, ximelagatran may become a first-line anticoagulant due to its ease of administration and lack of a need for drug monitoring. The results of these trials are eagerly awaited in helping to defining the place in therapy for this promising new agent.

Transesophageal echocardiography for early cardioversion of atrial fibrillation

Exclusion of thrombi in the setting of atrial fibrillation (AF) has important implications for early cardioversion. Cardioversion guided by transesophageal echocardiography (TEE) is a safe and relatively cost-effective technique with a high accuracy for detecting left-atrial thrombi. Nowadays, TEE-guided cardioversion may help to select patients suitable for early cardioversion. However, the long-term effect of early TEE-guided cardioversion on the maintenance of sinus rhythm needs to be determined.

Cardiovascular chemotherapy: anticoagulants

Anticoagulant therapy has changed dramatically during the past two years. Low molecular weight heparin has substantially replaced unfractionated heparin as the parenteral anticoagulant of choice. The use of warfarin has substantially increased, especially for prevention of stroke in the setting of atrial fibrillation. It has become clear that warfarin cannot be administered effectively in an unmonitored fixed-dose fashion. The parenteral direct thrombin inhibitor desirudin was shown to be efficacious in the prevention of deep vein thrombosis in man. Small thrombin and factor Xa inhibitors with in vivo oral anticoagulant activity have been identified.

Thromboembolism prophylaxis in chronic atrial fibrillation. Practice patterns in community and tertiary-care hospitals.

By 1992, several prospective trials established the efficacy of anticoagulation (AC) and to some extent antiplatelet (AP) agents in the prevention of stroke in the setting of atrial fibrillation (AF). The objective of this study was to determine whether practice patterns in AF stroke prophylaxis reflect the findings of clinical trials and whether stroke prophylaxis in AF differs between community hospitals and tertiary teaching hospitals. Retrospectively, 1250 hospital charts were reviewed. After patients who had undergone recent surgery, received treatment for malignancy, or were not in chronic AF on discharge were eliminated, 651 remaining records were analyzed for the presence of 26 clinical factors influencing the selection of thromboembolism prophylaxis. Descriptive statistics and logistic regression were used to analyze the association between clinical and demographic factors and the decision to treat with AC, AP, or no specific antiembolic therapy. Of the 651 patients in AF, 273 (42%) received noemboli prophylaxis while 219 (34%) were treated with AC (warfarin), 146 (22%) were treated with AP, and 13 (2%) received both agents. Patients discharged in AF from community hospitals were significantly less likely to be treated with either AC or AP agents than patients discharged from tertiary centers. A strong bias against thromboembolism prophylaxis with either AC or AP agents in AF existed with age over 45 years. Multivariate logistic regression indicated that the decision to treat was associated only with the presence of prosthetic valve, history of prior stroke, mitral disease, and absence of a recent gastrointestinal bleed or occult blood in stool. Even after adjustment for these factors, a significant bias against treatment with either AC or AP agents with advancing age and discharge from community hospitals remained. Thromboembolism prophylaxis with either AC or AP agents is underutilized in the setting of AF. Furthermore, factors known to increase the risk of embolization in AF such as age, hypertension, diabetes, and heart disease were not associated with decisions to treat with either AP or AC agents. This study suggests that the use of clinical guidelines suggested by trials of thromboembolism prophylaxis in AF could reduce the incidence of stroke.

Alcohol Ablation for Tachycardia Therapy

Alcohol Ablation for Tachycardia Therapy. Selective administration of ethanol into branches of the coronary arterial circulation has been proposed as a means of ablating cardiac fibers that give rise to cardiac arrhythmias, no matter where in the heart they might be located. In patients with uncontrollable ventricular rates in the setting of atrial fibrillation or atrial flutter, ethanol has been infused into the atrioventricular (AV) nodal artery in order to abolish or modify AV nodal conduction. Such a procedure is technically feasible in approximately 80% of patients and is successful in 70%–80% of individuals who are treated. Many of these patients require permanent pacemaker implantation because of chronic complete AV block. Intracoronary ethanol ablation has also been used to treat patients with AV nodal reentrant supraventricular tachycardia and ectopic atrial tachycardia, but there is scant clinical experience with the technique in these arrhythmias. Among patients with incessant or recurrent ventricular tachycardia (VT), intracoronary ethanol ablation has abolished clinical recurrences of arrhythmia in 78% of treated individuals. However, inability to identify a VT‐related arterial branch and other technical considerations may limit application of ethanol ablation to fewer than 50% of potential candidates with VT. Ethanol ablation is generally well tolerated, but significant complications have occurred, including ethanol‐induced occlusion of nontarget coronary arteries leading to unintended myocardial infarction. Procedure‐related death has also occurred. Ethanol ablation shows promise as a method for abolishing intractable tachycardias but further study is required to improve the safety of the technique and to define more precisely which patients are the best candidates in whom to consider this approach. (J Cardiovasc Electrophysiol, Vol. 3, pp. 354–364, August 1992)

Which cardiac disturbances should be treated with digoxin immune fab (ovine) antibody?

Digoxin excess can produce characteristic bradyarrhythmias, tachyarrhythmias, and hyperkalemia. The bradyarrhythmias, which consist of disturbances in conduction and block at the level of the atrioventricular and sinus nodes, are mediated by a direct and vagotonic effect. The vagotonic effect of excess digoxin may also result in a marked slowing of the sinus rate in the setting of severe toxicity. Digoxin increases automatic and triggered electrical activity in atrial muscle, His-Purkinje system, and ventricular muscle, which predisposes to tachycardias. Many of the tachyarrhythmias are relatively specific for the toxic effects of digoxin. Atrial tachycardias with variable atrioventricular block, accelerated junctional rhythms (especially in the setting of atrial fibrillation), and fascicular tachycardias are characteristic digoxin toxic rhythms. Digoxin-specific antibody fragments should be considered the treatment of choice for any digoxin toxic arrhythmia associated with hemodynamic compromise or the threat of hemodynamic compromise. Hyperkalemia, when due to acute severe digoxin toxicity, is also an appropriate indication for digoxin-specific Fab fragment therapy. When assessing the risk:benefit ratio for using digoxin-specific Fab fragment therapy, one needs to determine, in addition to the electrocardiographic manifestations and patient's hemodynamic status (1) the severity of toxicity, as indexed by the amount ingested and/or the serum digoxin concentration; (2) the expected time course for reversal of toxicity, which is usually determined by the status of renal function; (3) the need for digoxin to provide ventricular rate control or improved ventricular contractility and therapeutic alternatives to digoxin; (4) the presence of a strong allergy history; (5) the presence of such factors as increased age and severity of heart disease that may predispose to digoxin toxicity.(ABSTRACT TRUNCATED AT 250 WORDS)

Two False‐negative Responses to the Ajmaline Test in the Wolff‐Parkinson‐White Syndrome

Anterograde block in the accessory pathway with a short effective refractory period was observed after intravenous (IV) injection of 1 mg/kg of ajmaline in two patients with the Wolff-Parkinson-White syndrome. The possibility of a false-negative response to this test is discussed. Ajmaline is proposed as an emergency drug in the Wolff-Parkinson-White syndrome in the setting of atrial fibrillation with a very high ventricular rate.