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To determine the number of acute ischemic strokes associated with cessation of antiplatelet or anticoagulant medications, researchers retrospectively reviewed data from the ongoing, population-based Greater Cincinnati/Northern Kentucky Stroke Study. The authors identified 2197 ischemic strokes among the participants and categorized antithrombotic and antiplatelet use by these patients as current use, never used, and discontinuation within 60 days before the stroke.
Drug discontinuation was associated with 5.2% of the ischemic strokes; about half of these strokes occurred within 7 days after drug discontinuation. The authors conclude, “This finding emphasizes the need for thoughtful decision-making concerning antithrombotic medication use in the periprocedural period and efforts to improve patient compliance.”
Broderick JP et al. Withdrawal of antithrombotic agents and its impact on ischemic stroke occurrence. Stroke 2011 Jun 30; [e-pub ahead of print]. (http://dx.doi.org/10.1161/STROKEAHA.110.611905)
Comment
These findings show a clustering of ischemic strokes in the first week after cessation of antithrombotic therapy. However, the absolute event rate in the population at risk is unknown and was not identified in this study. Nevertheless, this study raises the issue of rebound hypercoagulability following cessation of antithrombotic therapy. Whether rebound hypercoagulability exists is controversial. Decades-old evidence suggests that during the first days after anticoagulant withdrawal, levels of coagulation factors VII and IX increase more rapidly than the natural anticoagulant proteins C and S (Eur Heart J 1991; 12:1225) and that recovery of antithrombin III, another natural anticoagulant, is delayed after heparin cessation (Lancet 1977; 2:581). Thus, a gap may occur between the factors that provoke and inhibit the coagulation process. Others have suggested that a similar pro-coagulable state may exist after cessation of antiplatelet drugs. Whether the increased stroke rate early after antithrombotic cessation in this study was caused by rebound hypercoagulability, by the reason for stopping the therapy (e.g., bleeding or cardiac surgery), or by other factors is uncertain. The prudent course is to advise patients to be compliant with their antithrombotic treatment and to minimize the duration of treatment cessation for medical procedures.