Differential use of warfarin for secondary stroke prevention in patients with various types of atrial fibrillation

Abstract

Anticoagulation therapy significantly reduces the incidence of thromboembolic events in patients with atrial fibrillation (AF), and warfarin therapy at discharge is a class I-indicated drug in patients with ischemic stroke with persistent or paroxysmal AF without contraindications. The aim was to determine whether participation in the Get With The Guidelines-Stroke (GWTG-S) quality improvement program would be associated with improved adherence to anticoagulation guidelines for patients with all types of AF. Adherence to warfarin treatment at hospital discharge was assessed in eligible patients with AF who presented with stroke or transient ischemic attack, based on type of AF. Of patients with stroke, 10.5% presented with some form of AF. When AF was documented using electrocardiography or telemetry (ECG) during the present admission, eligible patients were more likely to receive warfarin compared with patients for whom AF was reported using medical history only (78.8% vs 49.4%; p<0.0001). Improvement after GWTG-S participation in warfarin use was observed in patients with ECG-documented AF (73.8% at baseline vs 88.5% after the intervention; p<0.0001), but not patients using history only. Women and elderly patients were less likely to receive warfarin, and these gaps in treatment did not narrow during the quality improvement program for patients with ECG-documented AF and those with history only. In conclusion, anticoagulation for stroke prevention was underused in general for patients with AF, even in such high-risk groups as patients with stroke. GWTG-S was associated with improved adherence for patients with ECG-documented AF, but patients with a history of AF alone were largely untreated.

Figure 1

Flow diagram shows the subgroups for analysis in the study and their incidence.

Figure 2

Percentage of eligible patients with AF discharged with warfarin therapy prescribed at baseline (BL) and over 12 quarters (Q) of participation in the GWTG program. Solid line, percentage of adherence in patients with only a history of AF documented (group 2); dashed line, adherence in patients with electrocardiographically documented AF (group 1). Patients in group 1 had a higher adherence rate compared with patients in group 2. Adherence to anticoagulation guidelines improved over time in group 1, but not in group 2.

Figure 3

Percentage of younger versus elderly patients with AF documented using ECG (group 1) and history only (group 2) discharged with warfarin therapy prescribed at baseline (BL) and over 12 quarters (Q) of participation in the GWTG program. Younger patients were more likely to be discharged with anticoagulation treatment for both groups.

Figure 4

Odds ratios of warfarin therapy in elderly compared with younger patients. Black squares, patients with AF documented using ECG (group 1); black circles, patients with AF documented using history only (group 2). Elderly patients were less likely than younger patients to receive warfarin therapy regardless of how AF was documented. The treatment gap did not become narrower, shown by the decrease in odds ratios over 12 quarters of participation in the program.