Andersson, Ulrika

Objectives Compare the effect of apixaban and warfarin on coagulation and primary haemostasis biomarkers in atrial fibrillation (AF). Methods The biomarker substudy from the Apixaban for Reduction in Stroke and Other Thromboembolic Events in Atrial Fibrillation trial included 4850 patients with AF randomised to treatment with apixaban or warfarin. Sixty per cent of patients used vitamin K antagonist (VKA) within 7 days before randomisation. Prothrombin fragment 1+2 (F1+2), D-dimer, soluble CD40 ligand (sCD40L) and von Willebrand factor (vWF) antigen were analysed at randomisation and after 2 months of study treatment. Results In patients not on VKA treatment at randomisation, F1+2 and D-dimer levels were decreased by 25% and 23%, respectively, with apixaban, and by 59% and 38%, respectively, with warfarin (p<0.0001 for treatment differences for both). In patients on VKA at randomisation, F1+2 and D-dimer levels increased by 41% and 10%, respectively, with apixaban and decreased by 37% and 11%, respectively, with warfarin (p<0.0001 for treatment differences for both). sCD40L levels were slightly increased at 2 months, regardless of VKA or randomised treatment. Apixaban and warfarin also both reduced vWF antigen regardless of VKA treatment. The efficacy (stroke) and safety (bleeding) of apixaban compared with warfarin was similar irrespectively of biomarker levels at 2 months. Conclusions Treatment with apixaban compared with warfarin for stroke prevention in patients with AF was associated with less reduction in thrombin generation and fibrin turnover. This effect of apixaban could contribute to the clinical results where apixaban was superior to warfarin both in stroke prevention and in reducing bleeding risk. Trial registration number NCT00412984.

Background Cardiac biomarkers are independent risk markers in atrial fibrillation, and the novel biomarker–based ABC stroke score (age, biomarkers, and clinical history of prior stroke) was recently shown to improve the prediction of stroke risk in patients with atrial fibrillation. Our aim was to investigate the short‐term variability of the cardiac biomarkers and evaluate whether the ABC stroke risk score provides a stable short‐term risk estimate. Methods and Results According to the study protocol, samples were obtained at entry and also at 2 months in 4796 patients with atrial fibrillation followed for a median of 1.8 years in the ARISTOTLE (Apixaban for Reduction in Stroke and Other Thromboembolic Events in Atrial Fibrillation) trial. Cardiac troponin I, cardiac troponin T, and N‐terminal pro‐B‐type natriuretic peptide were measured with high‐sensitivity immunoassays. Associations with outcomes were evaluated by Cox regression. C indices and calibration plots were used to evaluate the ABC stroke score at 2 months. The average changes in biomarker levels during 2 months were small (median change cardiac troponin T +2.8%, troponin I +2.0%, and N‐terminal pro‐B‐type natriuretic peptide +13.5%) and within‐subject correlation was high (all ≥0.82). Repeated measurement of cardiac biomarkers provided some incremental prognostic value for mortality but not for stroke when combined with clinical risk factors and baseline levels of the biomarkers. Based on 8702 person‐years of follow‐up and 96 stroke/systemic embolic events, the ABC stroke score at 2 months achieved a similar C index of 0.70 (95% CI, 0.65–0.76) as compared with 0.70 (95% CI, 0.65–0.75) at baseline. The ABC stroke score remained well calibrated using predefined risk classes. Conclusions In patients with stable atrial fibrillation, the variability of the cardiac biomarkers and the biomarker‐based ABC stroke score during 2 months are small. The prognostic information by the ABC stroke score remains consistent and well calibrated with similar good predictive performance if patients are retested after 2 months. Clinical Trial Registration URL: http://www.clinicaltrials.gov . Unique identifier: NCT 00412984.

Objective Atrial fibrillation (AF) is a risk factor for stroke and mortality and the prothrombotic state has been linked to inflammation. In this study we evaluated the relationship between inflammatory biomarkers at baseline and future risk of cardiovascular events in the Apixaban for Reduction In Stroke and Other Thromboembolic Events in Atrial Fibrillation (ARISTOTLE) trial. Methods The ARISTOTLE trial randomised 18 201 patients with AF to apixaban or warfarin. Interleukin 6 (IL-6) and C reactive protein (CRP) were analysed in plasma obtained at randomisation from 14 954 participants, and median follow-up was 1.9 years. Association between quartile groups of IL-6 and CRP and outcomes were analysed by Cox regression adjusted for clinical risk factors and other cardiovascular biomarkers (NT-proBNP, troponin, GDF-15, cystatin C). Results The IL-6 median level was 2.3 ng/L (IQR 1.5–3.9), median CRP level was 2.2 mg/L (1.0–4.8). IL-6 and CRP were significantly associated with all-cause mortality independent of clinical risk factors and other biomarkers (HR (95% CI) 1.93 (1.57 to 2.37) and 1.49 (1.24 to 1.79), respectively, Q4 vs Q1). IL-6 was associated with myocardial infarction, cardiovascular mortality, and major bleeding beyond clinical risk factors but not in the presence of cardiovascular biomarkers (NT-proBNP, troponin, GDF-15, cystatin C). Neither inflammatory biomarker was associated with stroke/systemic embolism. Risk prediction for stroke, death and major bleeding was not improved by IL-6 or CRP when added to clinical risk factors and the other cardiovascular biomarkers (NT-proBNP, troponin, GDF-15, cystatin C). Conclusions In patients with AF on anticoagulation, after accounting for clinical risk factors and other biomarkers, biomarkers of inflammation were significantly associated with an increased risk of mortality. However, there were no associations with the risk of stroke or major bleeding. Trial registration number ClinicalTrials.gov identifier: NCT00412984 post-results.

Abstract BACKGROUND Although cardiac troponin is associated with outcomes in atrial fibrillation (AF), the complementary prognostic information provided by cardiac troponin I (cTnI) and cTnT is unknown. This study investigated the distribution, determinants, and prognostic value of cTnI and cTnT concentrations in patients with AF. METHODS Samples were collected. At the time of randomization, we analyzed cTnI and cTnT concentrations of 14806 AF patients in the Apixaban for Reduction in Stroke and Other Thromboembolic Events in Atrial Fibrillation (ARISTOTLE) trial using high-sensitivity assays. Correlations (Spearman), determinants (multivariable linear regression), and outcomes (adjusted Cox models and c-statistics) were investigated. RESULTS Concentrations of cTnI and cTnT were correlated (r = 0.70) and measurable in most participants [cTnI 98.5% (median 5.4 ng/L, ≥99th percentile in 9.2%) and cTnT 93.5% (median 10.9 ng/L, ≥99th percentile in 34.4%)]. Renal impairment was the most important factor affecting the concentrations of both troponins. cTnI increase was more associated with heart failure, vascular disease, and persistent/permanent AF, and cTnT with age, male sex, and diabetes. Over a median 1.9 years of follow-up, patients with both troponins above the median had significantly higher risk for stroke/systemic embolism [hazard ratio (HR) 1.72 (95% CI 1.31–2.27)], cardiac death [3.14 (2.35–4.20)], and myocardial infarction [2.99 (1.78–5.03)] than those with both troponins below median (all P &lt; 0.005). Intermediate risks were observed when only 1 troponin was above the median. When combined with clinical information, each marker provided similar prognostication and had comparable c-index. CONCLUSIONS cTnI and cTnT concentrations are moderately correlated and measurable in plasma of most AF patients. The risk of stroke and cardiovascular events is highest when both troponins are above median concentrations. Each troponin provides comparable prognostic information when combined with clinical risk factors. ClinicalTrials.gov/NCT00412984