Antithrombotic therapy prescribed for patients with non-rheumatic atrial fibrillation

Recent progress in antithrombotic therapy for atrial fibrillation

Atrial fibrillation (AF) is becoming a major health care burden as elderly populations increase. The increased risk of stroke and thromboembolisms in patients with AF is well documented and anti-coagulation with adjusted-dose warfarin is highly effective in reducing stroke risk, being superior to antiplatelet agents. Despite recognition of the epidemiological problem and the sound evidence base for thromboprophylaxis, as well as major guidelines recommending treatment, anticoagulation use is still suboptimal, given the dis-utility and limitations associated with warfarin. Recent developments in thromboprophylaxis for AF include efforts for better risk stratification for predictions of thromboembolic risk. Constant efforts are underway to develop newer, less cumbersome, alternatives to warfarin with similar (or better) efficacy. This review article provides an overview of the recent progress made, the potential challenges involved and the future of these therapeutic approaches.

Anticoagulants for atrial fibrillation: why is the treatment rate so low?

The incidence of atrial fibrillation (AF) is increasing in many countries along with aging demographics. Atrial fibrillation is clearly associated with an increased rate of stroke. Numerous large clinical trials have shown that dose-adjusted warfarin can reduce the stroke rate in these patients, particularly in the elderly, and clear guidelines for the use of anticoagulants in such patients have been published. However, many studies show that treatment rates remain disappointingly low (< or = 50%). Numerous barriers to the use of dose-adjusted warfarin exist, including practical, patient-, physician-, and healthcare system-related barriers. These include the complex pharmacokinetics of warfarin, the need for continuous prothrombin time monitoring and dose adjustments, bleeding events, noncompliance, drug interactions, and increased costs of monitoring and therapy. Possible solutions to this problem are discussed and include improved patient and physician education, the use of anticoagulation clinics, new approaches to AF, and potential treatment improvements through use of newer anticoagulants.

The utilization of antithrombotic prophylaxis for atrial fibrillation in a geriatric rehabilitation hospital

OBJECTIVE

To determine the utilization of anticoagulant and antithrombotic agents in older patients with atrial fibrillation.

DESIGN

Retrospective chart review.

SETTING

A geriatric rehabilitation hospital.

PATIENTS

Subjects were 102 patients with atrial fibrillation as an intermittent or prevailing cardiac rhythm during a hospital admission in the 1993 fiscal year.

MEASUREMENTS

Age, sex, and mental status of the patients; duration and etiology of atrial fibrillation; presence of contraindications to anticoagulants or antithrombotic agents; and utilization of these agents in this population.

RESULTS

Of 102 older patients with atrial fibrillation at admission, only 51 were taking some form of anticoagulant or antithrombotic therapy proven effective for stroke prophylaxis (19 warfarin and 32 aspirin). Although 67 patients had relative contraindications to anticoagulation with warfarin, only 25 of the 35 with no contraindications were taking warfarin at the time of discharge. In addition, of the 43 patients with contraindications to warfarin but no contraindications to aspirin, only 28 were prescribed antithrombotic therapy.

CONCLUSIONS

Although anticoagulation or antithrombotic therapies for atrial fibrillation appear to be relatively widely used, there are still significant windows of opportunity for the improvement of clinician practice patterns and clinical outcomes in older patients.

Physician variation in the management of patients with atrial fibrillation

OBJECTIVE

To investigate variations in the management of patients with atrial fibrillation among consultant physicians.

DESIGN

Questionnaire survey.

SUBJECTS

Consultant physicians in England, Wales, and Scotland.

RESULTS

214 consultant physicians (88 cardiologists and 126 non-cardiologists) were surveyed between May and July 1994. Most physicians (47.7%) reported that they saw one to five patients with atrial fibrillation weekly. Some 52% of cardiologists and 40% of non-cardiologists considered that the main factor influencing their decision of whether or not to anticoagulate was the clinical history--that is, heart failure, valve disease, or stroke. When encountering a patient admitted acutely with new onset atrial fibrillation, significantly more cardiologists (66% v 52%, chi 2 = 6.89, P = 0.03) would immediately start anticoagulant treatment, most favouring intravenous heparin. Most physicians would also introduce antiarrhythmic treatment or digoxin, but more cardiologists would attempt immediate pharmacological (39% v 18% of non-cardiologists, P < 0.001) or later electrical (86% v 69%, chi 2 = 11.7, P = 0.003) cardioversion to sinus rhythm, while non-cardiologists tended to prefer "rate control" with digoxin. Although many physicians would not continue antiarrhythmic treatment post-cardioversion, more cardiologists than non-cardiologists would do so (the commonest choice being class III agents) (31% v 17%, P = 0.04). Fewer non-cardiologists would continue anticoagulant treatment post-cardioversion (27% v 69% of cardiologists, chi 2 = 39.8, P < 0.0001). When treating patients with atrial fibrillation, decisions about anticoagulation were usually related to the perceived relative risk of thromboembolism versus haemorrhage derived for each of six case management scenarios in the questionnaire. There was, however, general agreement between cardiologists and non-cardiologists in the use of antithrombotic treatment in the management of lone atrial fibrillation, paroxysmal atrial fibrillation, and patients with atrial fibrillation and mitral valve disease or thyrotoxicosis.

CONCLUSION

There is considerable variation in the management of atrial fibrillation, with more cardiologists than non-cardiologists considering cardioversion to sinus rhythm (and the use of antiarrhythmic and anticoagulant treatment post-cardioversion) and thrombo-prophylaxis with anticoagulation. Guidelines on the management of this common arrhythmia are clearly required.