Response to Letter Regarding Article, “Net Clinical Benefit of Warfarin in Patients With Atrial Fibrillation: A Report From the Swedish Atrial Fibrillation Cohort Study”
In Dr Spiegel's opinion, our registry study of 182 678 patients with atrial fibrillation (AF) offers a solution to a dilemma regarding minor valvular dysfunction and the choice between rivaroxaban and warfarin for stroke prophylaxis. We doubt whether it is prudent to draw such far-reaching conclusions from our study.
The main message our article1 was that almost all patients with AF benefit from warfarin prophylaxis. Patients with almost all combinations of stroke and bleeding risks at baseline experienced fewer strokes, fewer intracranial hemorrhages, and lived longer if they used warfarin than if they did not. The most important exception to this rule was patients with lone AF who are at very low risk (essentially CHA2DS2-VASc score=0, where CHA2DS2-VASc is an acronym for important risk factors for stroke in AF patients; congestive heart failure, hypertension, age, diabetes, previous stroke or TIA, vascular disease, and female sex) even without warfarin. The CHADS2 score is not the way to define low risk because the stroke rate in patients with a CHADS2 score of 0 can range from 0.8%/y to 3.2%/y.2
An important limitation to our study was that it was made on binary registry data. We cannot be sure about not having included some patients with valvular disease even though we did our best to exclude them. The presence or absence of valvular disease was not an important, major issue in our study because warfarin can be used in both valvular and nonvalvular AF. Regarding the novel oral anticoagulants, we have no evidence supporting their use in patients with valvular AF.
Dr Spiegel points out that most patients with AF have at least minor valvular dysfunction and that we therefore should continue to use warfarin for the majority of patients. We feel this is rather extreme. The novel oral anticoagulants are a major advance for stroke prevention in nonvalvular AF, but should be reserved for those who are clearly without significant valvular disease. Of note, some patients with minor, nonsignificant valvular disease could have been included in the recent trials based on their trial inclusion criteria.
Leif Friberg, MD, PhD
MårtenRosenqvist, MD, PhD
Karolinska Institute and Department of Cardiology
Danderyd University Hospital
Gregory Y.H. Lip, MD
University of Birmingham Centre for Cardiovascular Sciences
Dr Friberg is a consultant to Sanofi-aventis, Boehringer-Ingelheim, and BMS. Dr Rosenqvist is a consultant to Sanofi-aventis and Nycomed, Sweden. He has also been national coordinator for the RECORD, REALISE, and ARISTOTLE studies, and is a member of the steering group for the REALISE study. He has been reimbursed by Sanofi-aventis and Boehringer Ingelheim for lectures. Dr Lip has received funding for research, educational symposia, consultancy, and lecturing from different manufacturers of drugs used for the treatment of AF and thrombosis.
- © 2012 American Heart Association, Inc.