Author Interviews, Heart Disease / 28.07.2017
Contraindications Not The Reason Atrial Fibrillation Patients Not Prescribed Anticoagulants
MedicalResearch.com Interview with:
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Prof. Marshall[/caption]
Tom Marshall, MSc, PhD, MRGP, FFPH
Professor of public health and primary care
Institute of Applied Health Research
University of Birmingham
Birmingham UK
MedicalResearch.com: What is the background for this study? What are the main findings?
Response: It is widely recognised that anticoagulants are underused in patients with atrial fibrillation (AF) although they are effective in reducing risk of stroke. We investigated whether this could be explained by the fact that many AF patients have conditions which are considered relative contraindications to their use.
We analysed electronic medical records from 645 general practices from 2004 to 2015 and included over 1 million patients with AF. We found that about 6% of AF patients had are relative contraindications such as recent history of major bleeding. In each of the 12 years, similar numbers of patients with and without contraindications were prescribed anticoagulants.
Prof. Marshall[/caption]
Tom Marshall, MSc, PhD, MRGP, FFPH
Professor of public health and primary care
Institute of Applied Health Research
University of Birmingham
Birmingham UK
MedicalResearch.com: What is the background for this study? What are the main findings?
Response: It is widely recognised that anticoagulants are underused in patients with atrial fibrillation (AF) although they are effective in reducing risk of stroke. We investigated whether this could be explained by the fact that many AF patients have conditions which are considered relative contraindications to their use.
We analysed electronic medical records from 645 general practices from 2004 to 2015 and included over 1 million patients with AF. We found that about 6% of AF patients had are relative contraindications such as recent history of major bleeding. In each of the 12 years, similar numbers of patients with and without contraindications were prescribed anticoagulants.














Dr. T. Jared Bunch[/caption]
T. Jared Bunch, MD
Director of Heart Rhythm Research
Medical Director for Heart Rhythm Services
Intermountain Healthcare System
MedicalResearch.com: What is the background for this study? What are the main findings?
Dr. Bunch: Approximately 6 years ago we found that patients with atrial fibrillation experienced higher rates of all forms of dementia, including Alzheimers disease. At the time we started to ask the questions of why this association existed. We know that atrial fibrillation patients experience higher rates of stroke. These patients are placed on blood thinners, most commonly warfarin, to lower risk of stroke which at the same time expose that patient to a higher risk of intracranial bleeding. One possibility to explain the association was that perhaps dementia in the manifestation of many small clots or bleeds in the brain that in total lead to cognitive decline. If this is the case, then the efficacy and use of anticoagulation is very important in atrial fibrillation patients.
We conducted additional studies that showed this to be the case. In patients with no history of dementia, managed long-term with warfarin anticoagulation, those that had levels that were frequently too higher or too low that resulted in poor times in therapeutic range, experienced significantly higher rates of dementia. The risk was highest in younger atrial fibrillation patients that were less than 80 years of age. We then found that in atrial fibrillation patients that were frequently over anticoagulated and also use an antiplatelet agent, aspirin or plavix, the dementia rates nearly doubled. At this point we raised the question if atrial fibrillation increased the risk beyond anticoagulation, or does anticoagulation efficacy drive most of the risk. This question formed the background of the current study.
Dr. Ben Freedman[/caption]
Dr. Ben Freedman OAM
Deputy Director Research Strategy, Heart Research Institute/Charles Perkins Centre
Professor of Cardiology, Sydney Medical School
Head Vascular Biology Anzac Research Institute
Honorary VMO, Concord Repatriation General Hospital
University of Sydney
MedicalResearch.com: What is the background for this study?
Dr. Freedman: Guidelines recommend that patients with atrial fibrillation (AF) at high enough risk for stroke should be treated with anticoagulant. Anticoagulant drugs are remarkably effective in reducing stroke risk by about two thirds, and death by between a quarter and a third. Unfortunately, strokes can still occur when patients are prescribed anticoagulant for Atrial Fibrillation, and it is often presumed this residual risk of stroke represents treatment failure, though there are few data about this important issue.
MedicalResearch.com: What are the main findings?
Dr. Freedman: We were able to compare the risk of stroke in a cohort of patients with AF commenced on anticoagulant, with a very large closely-matched cohort seen in general practice at the same time but without AF. This is a unique comparison. We found that the residual risk of stroke in such anticoagulant-treated patients was virtually identical to that in the matched control cohort. The implication is that the residual risk of stroke may not be treatment failure, but the risk of non-cardioembolic stroke in people of a similar age and stroke risk profile but without Atrial Fibrillation. The residual risk of death in those on anticoagulant was higher than the matched controls, and intermediate between the control rate and the mortality rate for untreated AF.

Dr. Barnes[/caption]
MedicalResearch.com Interview with:
Geoffrey Barnes, MD, MSc
Clinical Lecturer
Cardiovascular Medicine and Vascular Medicine
University of Michigan Health System
Medical Research: What is the background for this study?
Dr. Barnes: Although warfarin has been the primary anticoagulant used for stroke prevention in atrial fibrillation for over 60 years, four new direct oral anticoagulants (DOACs) have been introduced into the market since 2010. Dabigatran, which directly inhibits thrombin, was found to have better prevention of ischemic stroke and a significant reduction in hemorrhagic stroke (bleeding strokes) for patients with 

