Atrial fibrillation (irregular and rapidly beating atria) increases the risk of cardiac blood clots, which can cause ischaemic stroke. Warfarin has been used for decades for people at high risk of stroke because of its blood-thinning capability; however there are many drawbacks of warfarin treatment: an increased risk of bleeding, and possible interaction with food and other medication necessitating at least monthly blood testing and frequent dose adjustment. The oral direct thrombin-inhibitor ximelagatran could be a more reliable alternative to warfarin for people at high stroke risk.
In an international study (SPORTIF III: Stroke Prevention using an ORal Thrombin Inhibitor in atrial Fibrillation), 3407 patients from Europe, Asia, and Australia with atrial fibrillation and one or more stroke risk factors were randomly allocated warfarin or oral ximelagatran. Average follow-up took place after 17 months.
Oral ximelagatran was at least as effective in reducing the frequency of stroke or systemic blood clots (the primary outcomes) as warfarin (relative risk reduction 30%, absolute risk reduction 0.7% for ximelagatran; however this was not statistically significant). Rates of disabling or fatal stroke, death, and major bleeding were similar between both groups.
Lead investigator S Bertil Olsson from University Hospital Lund, Sweden, comments: "We have shown that ximelagatran, administered in a fixed dose without coagulation monitoring, protects high-risk patients with atrial fibrillation against thromboembolism at least as effectively as well-controlled warfarin, and is associated with less bleeding. The preliminary reported SPORTIF V trial presented at the November 2003 American Heart Association meeting has further verified the efficacy and safety in a similar population."
In an accompanying Commentary (p 1686), Freek Verheugt from University Medical Centre, Nijmegen, Netherlands, concludes: "If safety seems good in a broader population of patients, ximelagatran may find its way into general use in atrial fibrillation. But this process will take a while, and in the meantime the ACTIVE study with clopidogrel, which has a more established safety profile than ximelagatran so far, will be finished. Depending on the outcome, physicians willing to switch from warfarin for patients with atrial fibrillation must decide which agent they will go for."
Contact: Professor S. Bertil Olsson, Department of Cardiology, University Hospital Lund, SE-221 85, Sweden; T): 46-4617-3517; F): 46-4615-7857; E): firstname.lastname@example.org. Professor Freek W A Verheugt, Heartcentre, University Medical Centre St Radboud, 6500 HB Nijmegen, Netherlands; T): 31-24-361-4220; F): 31-24-354-0537; E): email@example.com.