Hylek, Elaine M.

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 Chronic kidney disease ( CKD ) is a common comorbidity in patients with atrial fibrillation. The presence of CKD complicates drug selection for stroke prevention and rhythm control. Methods and Results Patients enrolled in ORBIT AF (Outcomes Registry for Better Informed Treatment of Atrial Fibrillation) with baseline renal function and follow‐up data were included (N=9019). CKD was defined as an estimated creatinine clearance <60 mL /min. Patient characteristics were compared by CKD status, and Cox proportional hazards modeling was used to examine the association between oral anticoagulant ( OAC ) use and outcomes and antiarrhythmic drug use and outcomes stratified by CKD stages. At enrollment, 3490 (39%) patients had an estimated creatinine clearance <60 mL /min. Patients with CKD were older and had higher CHA 2 DS 2 VAS c and Anticoagulant and Risk Factors in Atrial Fibrillation (ATRIA) scores. A rhythm control strategy was selected less frequently in patients with CKD , while OAC use was lower among Stage IV and V CKD patients. After adjustment, no significant interaction was noted for OAC and CKD on all‐cause mortality ( P =0.5442) or cardiovascular death ( P =0.1233), although a trend for increased major bleeding ( P =0.0608) and stroke, systemic embolism or transient ischemic attack ( P =0.0671) was observed. No interaction was noted for antiarrhythmic drug use and CKD status on all‐cause mortality ( P =0.9706), or stroke, systemic embolism or transient ischemic attack ( P =0.4218). Conclusions Patients with atrial fibrillation and CKD are less likely to be treated with rhythm control. Patients with advanced CKD are less likely to receive OAC . Finally, outcomes with OAC in patients with advanced CKD may be materially different with higher rates of both bleeding and stroke.

Background Current American College of Cardiology/American Heart Association guidelines suggest that for patients with atrial fibrillation who are at low risk for stroke (CHA 2 DS 2 VASc=1) (or women with CHA 2 DS 2 VASc=2) a variety of treatment strategies may be considered. However, in clinical practice, patterns of treatment in these “low‐risk” patients are not well described. The objective of this analysis is to define thromboembolic event rates and to describe treatment patterns in patients with low‐risk CHA 2 DS 2 VASc scores. Methods and Results We compared characteristics, treatment strategies, and outcomes among patients with a CHA 2 DS 2 VASc=0, CHA 2 DS 2 VASc=1, females with a CHA 2 DS 2 VASc=2, and CHA 2 DS 2 VASc ≥2 in ORBIT‐AF (Outcomes Registry for Better Informed Treatment of Atrial Fibrillation) I & II. Compared with CHA 2 DS 2 VASc ≥2 patients (84.2%), those with a CHA 2 DS 2 VASc=0 (60.3%), 1 (69.9%), and females with a CHA 2 DS 2 VASc score=2 (72.4%) were significantly less often treated with oral anticoagulation ( P <0.0001). Stroke rates were low overall and ranged from 0 per 100 patient‐years in those with CHA 2 DS 2 VASc=0, 0.8 (95% confidence interval [CI] [0.5–1.2]) in those with CHA 2 DS 2 VASc=1, 0.8 (95% CI [0.4–1.6]) in females with a CHA 2 DS 2 VASc score=2, and 1.7 (95% CI [1.6–1.9]) in CHA 2 DS 2 VASc ≥2. All‐cause mortality (per 100 patient‐years) was highest in females with a CHA 2 DS 2 VASc score=2 (1.4) (95% CI [0.8–2.3]), compared with patients with a CHA 2 DS 2 VASc=0 (0.2) (95% CI [0.1–1.0]), and CHA 2 DS 2 VASc=1 (1.0) (95% CI [0.7–1.4]), but lower than patients with a CHA 2 DS 2 VASc ≥2 (5.7) (95% CI [5.4–6.0]). Conclusion The majority of CHA 2 DS 2 VASc=0‐1 patients are treated with oral anticoagulation. In addition, the absolute risks of death and stroke/transient ischemic attack were low among both male and females CHA 2 DS 2 VASc=0‐1 as well as among females with a CHA 2 DS 2 VASc score=2. Clinical Trial Registration URL: http://www.clinicaltrials.gov . Unique identifier: NCT01701817.

Background Oral anticoagulation ( OAC ) reduces stroke risk in atrial fibrillation, but bleeding is a frequent side effect. The decision to discontinue or modify medication regimens in response to a bleeding event may differ according to bleeding site and severity. Methods and Results We used data from a large, national outpatient registry, ORBIT ‐ AF (Outcomes Registry for Better Informed Treatment of Atrial Fibrillation; 2010–2011), to evaluate event characteristics and OAC management following the first bleeding event occurring during follow‐up. Bleeding events were classified into 3 categories: (1) International Society of Thrombosis and Hemostasis major bleeding, (2) clinically relevant nonmajor bleeding requiring medical attention, and (3) nuisance bleeding not requiring medical attention (eg, bruising, hemorrhoidal bleeding). Of 9743 patients enrolled in ORBIT ‐ AF with follow‐up data, 510 (3.23/100 subject‐years) experienced a major bleed, 615 (3.90/100 subject‐years), experienced a clinically relevant nonmajor bleed, and 1558 (9.87/100 subject‐years) experienced a nuisance bleed, among first bleeds over 2 years. Nearly one third of patients (31.6%) discontinued OAC therapy following a major bleeding event, 12.7% following a clinically relevant nonmajor bleed, and 4.5% following a nuisance bleed. Compared with those who experienced a clinically relevant nonmajor or nuisance bleed, patients who experienced a major bleed were more likely to be black and female and to have a history of heart failure and stroke. Those who discontinued were more likely to have central nervous system or gastrointestinal bleeding than those who persisted on OAC therapy. Conclusions Overall, 1 in 3 patients who experienced a major bleed was no longer anticoagulated after the event. Those who discontinued OAC were more likely to have central nervous system or gastrointestinal bleeding than those who persisted on OAC .

Background: Bleeding is commonly cited as a reason for stopping oral anticoagulants (OACs). Whether minor bleeding events (nuisance bleeding, NB) in patients with atrial fibrillation on OACs are associated with OAC discontinuation, major bleeding, and stroke/systemic embolism (SSE) is unknown. Methods: Within the ORBIT-AF prospective, outpatient registry (Outcomes Registry for Better Informed Treatment of Atrial Fibrillation), we identified 6771 patients ≥18 years of age at 172 sites with atrial fibrillation and eligible follow-up visits. NB was ascertained from the medical record and was defined as minor bleeding that did not require medical attention (eg, bruising, hemorrhoidal bleeding). We used multivariable pooled logistic regression modeling to evaluate the associations between NB and major bleeding and SSE in the 180 days after documentation of NB. Our unit of analysis was the patient visit, occurring at ≈6-month intervals for a median of 1.5 years following enrollment. Changes in anticoagulation treatment satisfaction after NB were examined descriptively in a subset of patients. Results: The median age of the overall population was 75.0 (interquartile range, 67.0–81.0); 90.0% were white and 42.5% were female. Among 6771 patients (18 560 visits), n=1357 (20.0%) had documented NB, for an incidence rate of 14.8 events per 100 person-years. Over 96.4% of patients remained on OAC therapy after the NB event. Overall, 287 (4.3%) patients experienced major bleeding and 64 (0.96%) had a SSE event during follow-up. NB was not associated with a significant increased risk of major bleeding over 6 months in models adjusting for the ATRIA bleeding score (Anticoagulation and Risk Factors in Atrial Fibrillation) (odds ratio, 1.04; 95% confidence interval, 0.68–1.60; P =0.86). NB was also not associated with increased SSE risk over 6 months in models adjusting for the CHA 2 DS 2 -VASc risk score (odds ratio, 1.24; 95% confidence interval, 0.53–2.91; P =0.62). Conclusions: NB is common among patients with atrial fibrillation on OACs. However, NB was not associated with a higher risk of major bleeding or SSE over the next 6 months, suggesting its occurrence should not lead to changes in anticoagulation treatment strategies in OAC-treated patients. Clinical Trial Registration: URL: https://www.clinicaltrials.gov . Unique identifier: NCT01165710.

Background Mineralocorticoid receptor antagonist ( MRA ) therapy may be beneficial to patients with atrial fibrillation ( AF ), but little is known about their use in patients with AF and subsequent outcomes. Methods and Results In order to better understand MRA use and subsequent outcomes, we performed a retrospective cohort study of the contemporary ORBIT ‐ AF (Outcomes Registry for Better Informed Treatment of Atrial Fibrillation) registry. AF progression and cardiovascular outcomes were compared using propensity‐matched Cox proportional hazards modeling according to MRA use at baseline and new MRA use at follow‐up versus patients with no MRA use. Among 7012 patients with nonpermanent AF , 320 patients were taking MRA at enrollment, and 416 patients initiated MRA use during follow‐up. The mean patient age was 72.5 years, 56.3% were men, and 70.4% had paroxysmal AF . Among all patients taking MRAs, 434 (59.0%) had heart failure, 655 (89.0%) had hypertension, and 380 (51.6%) had both. After adjustment, new MRA use was not associated with reduced AF progression (hazard ratio, 1.18; 95% confidence interval, 0.88–1.58; P =0.27) but showed a trend towards lower risk of stroke, transient ischemic attack, or systemic embolism (hazard ratio, 0.17; 95% confidence interval, 0.02–1.23; P =0.08). Results were similar for a comparison of new MRA users and baseline MRA users compared with nonusers. Conclusions In community‐based outpatients with AF , the majority of MRA use was for heart failure and hypertension. MRA use also trended towards lower adjusted stroke risk. Future studies should test the hypothesis that MRA use may decrease the risk of stroke in patients with AF .