Anticoagulation Uptake in Emergency Department Patients With Atrial Fibrillation
To the Editor:
Scott et al1 report that atrial fibrillation (AF) is commonly seen in emergency department patients and antithrombotic prophylaxis was suboptimal, despite the well-established benefits of thromboprophylaxis in AF.2
The data reported by Scott et al1 are not altogether unexpected, and we are pleased that they have confirmed our previous observations.3–5 In 1994, we reported that AF was present in 6% of acute medical admissions to a Scottish district general hospital, and there was a suboptimal application of standard investigations for AF and a poor provision of thromboprophylaxis.3 Indeed, of the 102 patients presenting with known AF in a 6-month period, only 20% were taking warfarin and 17% were on aspirin, and of those not on warfarin only 34% had contraindications.3 These observations were confirmed in a multiethnic population in Birmingham, England, where only 28% of the 103 patients with previously known AF were already anticoagulated.4 The latter study also highlighted ethnic differences in associated etiological factors associated with AF, with hypertension being a common underlying cause of AF in Afro-Caribbeans, while ischemic heart disease was common among Indo-Asians.
Nevertheless, the improved, but still inadequate, rates of anticoagulation for AF reported by Scott et al1 (40% of the 556 patients with a history of AF), may be the result of more widespread recognition of the need for anticoagulation in AF.2 Of additional concern is their finding that of those patients on warfarin, 61% were outside the recommended target range of INR of 2 to 3, suggesting that even those who receive warfarin may not have their anticoagulation adequately managed. This complements our recent observations that many patients possess very limited knowledge of AF as well as its consequences and therapy.6 In particular, we have highlighted significant differences between different ethnic groups in terms of their knowledge of the risks, actions, and benefits of warfarin as well as AF itself.6
The study by Scott et al1 also poses the question whether the emergency department provides the best setting to correct the apparent deficit in AF management. In our general practice survey, less than one third of patients with AF had ever presented to hospital practice,5 suggesting that the identification of AF patients who would benefit from anticoagulation should, for the most part, be encouraged in the primary care setting, where the majority of AF patients are actually managed. It is likely that in the emergency department, warfarin initiation would only contribute a relatively small amount to actually increasing the number of AF patients receiving warfarin. Furthermore, a survey of Accident and Emergency Department (the equivalent of the “emergency department” in North America) consultants in the United Kingdom revealed a general reluctance to initiate oral anticoagulation in AF, with 51% stating that they would not do this routinely in an acute presentation.7 Our observations would suggest that there may be significant limitations to the initiation of anticoagulant therapy in the emergency department setting, at least in the United Kingdom.
Scott PA, Pancioli AM, Davies LA, et al. Prevalence of atrial fibrillation and antithrombotic prophylaxis in emergency department patients. Stroke. 2002; 33: 2664–2669.
Lip GYH, Hart RG, Conway DSG. ABC of antithrombotic therapy: antithrombotic therapy for atrial fibrillation. BMJ. 2002; 325: 1022–1025.
Lip GYH, Tean KN, Dunn FG. Treatment of atrial fibrillation in a district general hospital. Br Heart J. 1994; 71: 92–95.
Lip GYH, Golding DJ, Nazir M, et al. A survey of atrial fibrillation in general practice: the West Birmingham Atrial Fibrillation Project. Br J Gen Pract. 1997; 47: 285–289.
Lip GYH, Kamath S, Jafri M, Mohammed A, Bareford D. Ethnic differences in patient perceptions of atrial fibrillation and anticoagulation therapy: the West Birmingham Atrial Fibrillation project. Stroke. 2002; 33: 238–242.
Williams E, Ansari M, Lip GYH. Managing atrial fibrillation in the Accident and Emergency department. Q J Med. 2001; 94: 1–6.
We appreciate Drs Freestone and Lip bringing our attention to their earlier work regarding the prevalence of atrial fibrillation and the use of antithrombotic prophylaxis in Great Britain and agree work remains to improve care in this at-risk population. We disagree, however, with the statement that emergency departments (EDs) could likely make only a small contribution to increasing the number of patients on warfarin. Although the EDs may not be the point at which to start outpatient anticoagulation (and this remains to be established) our findings clearly indicate a significant potential for ED identification of untreated patients and initiating care—either through referral mechanisms or direct physician contact—to increase antithrombotic use. It is likely the yield of such an approach will be substantially different in the United States given the marked differences in health care delivery between the two countries.