Anna GarrettPoor blood pressure control is associated with a substantially higher risk of stroke or systemic embolism in patients with atrial fibrillation. A subanalysis of the Phase 3 ARISTOTLE trial indicates that apixaban reduces the risk of stroke regardless of whether a patient’s blood pressure is controlled.
In ARISTOTLE, a total of 15,916 (87.5%) patients had a history of hypertension requiring treatment. During the trial, 50% of patients had poorly controlled hypertension (defined as systolic blood pressure >140 mm Hg and/or diastolic blood pressure >90 mm Hg) at some point. Poorly controlled hypertension during the course of the trial was associated with a significant 53% increase in the risk of stroke or systemic embolism. Apixaban was consistent in reducing the risk of stroke or systemic embolism vs, warfarin in patients with and without poor blood pressure control during the trial.
In this subanalysis, the effect of apixaban in reducing the risk of stroke and systemic embolism versus warfarin was consistent with the main results of the ARISTOTLE trial. These results were also consistent with the results of subanalyses of other comorbidities from the ARISTOTLE trial, which included congestive heart failure, advanced age, renal impairment, and previous stroke.
Source: “In a subanalysis, the benefits of Eliquis (apixaban) vs. warfarin in reducing the risk of stroke in patients with nonvalvular atrial fibrillation were consistent, regardless of blood pressure control.” Press release. Princeton NJ and New York. March 27, 2014. http://bit.ly/eliquisPR. Accessed April 6, 2014.
Mental illness complicates warfarin management
Nearly one-third of Americans have been diagnosed with some type of mental health condition. For patients on warfarin, the type and severity of these problems can greatly affect a patient’s adherence and outcomes.
A study of veterans with atrial fibrillation and mental illness showed that patients with psychiatric problems were less likely to be prescribed warfarin. Those who were prescribed warfarin were more likely to have INRs that were out of range. Patients without mental health conditions were in therapeutic range 65.9% of the time vs. 56.8% for veterans with mental illness.
Current practice guidelines don’t address whether mental illness should be considered when choosing anticoagulant therapy. Consideration should be given to a patient’s individual needs and preferences, with particular attention placed on individual stroke risk, ability to tolerate anticoagulation without bleeding, and access to adequate anticoagulation monitoring.
Source: Walker GA, Heidenreich PA, Phibbs CS, et al. Mental illness and warfarin use in atrial fibrillation. Am J Manag Care. 2011;17(9):617–624.
Warfarin benefits outweigh risks in CKD
A Swedish study has concluded that the benefits of anticoagulation with warfarin outweigh the risks in patients with chronic kidney disease (CKD), even for those with the most severe kidney damage. The research showed warfarin treatment reduced the risk of thrombotic events in post-MI patients with atrial fibrillation and CKD, without increasing their risk of bleeding.
The study included 24,317 patients who survived an MI and had atrial fibrillation with or without chronic kidney disease. Over 12 months of follow-up, the patients treated with warfarin had an 18% lower relative risk of recurrent MI, stroke, or death than the untreated patients had; risk of hemorrhage was the same. The same pattern occurred among those patients with CKD and across different levels of severity of CKD. Warfarin treatment resulted in 18%, 17%, 13%, and 20% reductions in the risk of recurrent MI, stroke, or death among patients with eGFR >60, >30-60, >15-30, and <15, mL/min, respectively, without an increase in bleeding risk.
International kidney disease guidelines were recently modified to advise caution with warfarin use in patients with CKD because of their increased bleeding risk, while the National Institute for Health Care and Excellence (NICE), the British healthcare quality agency, continues to note that little is known about the benefits vs. risks of treatment in patients with CKD in draft-updated atrial fibrillation guidance published earlier this year.
Source: Carrero JJ, Evans M, Szummer K, et al. Warfarin, kidney dysfunction, and outcomes following acute myocardial infarction in patients with atrial fibrillation. JAMA 2014; 311(9):919–928.