Background: Atrial fibrillation (AF) is a major cause of ischaemic stroke (IS), however the risk can be mitigated with the use of oral anticoagulants (OAC). We aimed to determine the demographics, risk profile, stroke rates and management of AF patients.
Method: We sampled AF admissions between 1988 and 2020 from the National Minimum Dataset. We collected data on demographics, antithrombotic prescriptions, and comorbidities to determine CHA2DS2 VASc score (heart failure, hypertension, diabetes, vascular disease, female sex, age 65-74 years [1 point each]; age ≥75, previous IS/TIA [2 points]) on 31st August 2020 and the stroke rates at one year.
Results: We identified 304 patients (60.2% males); 77.6% Europeans, 12.2% Māori, and 9.2% Pacific peoples. Median age at AF diagnosis was 65.6 years (IQR 56.5-75), which varied across ethnicities: 68, 55.5 and 59.9 years respectively, (p<0.001). 55.9% had paroxysmal AF and 29.6% had previous cardioversion/pulmonary vein isolation. Past medical history included impaired left ventricular function (13.5%), hypertension (59.2%), diabetes (18.8%), and previous IS/TIA (14.8%). 81.3% were considered at high-risk of stroke (defined as CHA2DS2 VASc ≥2). OAC were prescribed in 68.4%; warfarin (14.8%), dabigatran (63.9%), and rivaroxaban (21.2%); and were more frequently prescribed in high-risk than low-risk patients (77.3% Vs 29.8%, p<0.001). Annualised stroke rates were 1.6% (n=5), occurring exclusively in high-risk patients (four Europeans, one Māori); two of these patients were OAC naive. Four strokes occurred in patients with paroxysmal AF.
Conclusion: Antithrombotic treatment in high-risk AF patients remains suboptimal, highlighting an opportunity for improvements in management.