Incidence of Vascular Outcomes in Patients with Atrial Fibrillation,

To describe the characteristics of patients with recently diagnosed atrial fibrillation (AF) and to estimate the incidence of vascular outcomes in patients with AF.

A cohort study in newly diagnosed AF patients (2005–2010) without heart valve replacement/problems was performed in the General Practice Research Database (GPRD), UK. Linked data to the Hospital Episode Statistics (HES) and death certificates from the Office of National Surveillance (ONS) were included. Current vitamin K antagonists (VKA) treatment was defined as a valid prescription/INR measurement during the last 28 days, recent as a treatment period from 28 to 90 days after the last prescription/INR measurement, and past treatment as more than 90 days after last treatment/INR measurement. No treatment was the time between diagnosis of AF and first prescription/INR measurement, or the whole follow-up for patients that have never been treated. Vascular outcomes – first ever recorded – were assessed as primary hospital admission diagnosis recorded in HES, i.e. myocardial infarction (MI), stroke, and systemic peripheral arterial embolism (SPAE).

Data from 16,513 AF patients could be linked; 48% were female, the mean age (std) was 74 (12) years, the median duration of follow-up was 1.7 years (range 0–5). According to CHADS₂ score 21% were at low risk, 65% at moderate and 14% at high risk for stroke. Overall 55.8% of the patients had at least one period of VKA use.

Overall, 1,151 vascular events were recorded (403 MIs, 716 strokes, 68 SPAE). The incidence (per 100 patient years (95% CIs)) of vascular events was 3.8 (3.5 – 4.0), 1.3 (1.2 – 1.4) for MI, 2.3 (2.1 – 2.5) for stroke and 0.2 (0.2 – 0.3) for SPAE. Stratification by period of VKA use resulted in incidences for current, recent, past and non users for MI of 0.7 (0.6 – 0.9), 0.7 (0.4 – 1.2), 1.1 (0.8 – 1.5), 1.9 (1.7 – 2.1), for stroke of 0.9 (0.8 – 1.1), 2.2 (1.6 – 2.9), 2.4 (1.9 – 2.9), 3.4 (3.1 – 3.7), and for SPAE of 0.2 (0.2 – 0.3), 0.2 (0.1 – 0.3), 0.3 (0.1 – 0.6), 0.2 (0.1 – 0.3), 0.2 (0.2 – 0.3).

In this cohort study, a trend towards lower incidences of vascular events, specifically stroke and MI, was detected during VKA use compared to past/no use. No causal conclusions can be drawn from these crude incidence estimates, but the trends are in line with the clinical expectations of anticoagulation in AF patients.

Clemens:Boehringer Ingelheim Pharma GmbH & Co. KG: Employment. Diana:Boehringer Ingelheim GmbH: Employment. Bartels:Boehringer Ingelheim GmbH: Employment.