Recovery time of platelet function after aspirin withdrawal.

INTRODUCTION: Inappropriate antiplatelet therapy discontinuation increases the risk of thrombotic complications and bleeding after dental procedures. To determine the platelet reactivity recovery time after aspirin withdrawal in vivo, our study was conducted in patients with low-risk cardiovascular disease who can stop aspirin administration following the guidelines stipulated by the American College of Chest Physicians. The time it takes for platelet activity to normalize and the diagnostic accuracy of testing methods were assessed for a residual antiplatelet activity with multiple electrode aggregometry. Our study included patients with clinically indicated hypertension preparing for a dental extraction procedure.

MATERIALS AND METHODS: A total of 212 patients not taking aspirin (control group) and 248 patients with hypertension receiving long-time aspirin treatment at a 100-mg daily dose were prospectively included in the study, which involved stopping aspirin intake before dental extraction. The residual platelet activity and dental bleeding in patients who stopped aspirin intake were analyzed and compared with those of the control group. In addition, platelet reactivity recovery time and bleeding risk in patients who stopped taking aspirin every 24 hours for 0 to 5 days (0-143 hours) before dental extraction was also assessed.

RESULTS: Platelet reactivity normalized 96 hours after aspirin withdrawal. The cut-off value of 49 arbitrary units in the arachidonic acid platelet aggregation test excluded the effect of aspirin with 91% sensitivity and 66% specificity. AUC showed 0.86 (P < 0.001) diagnostic accuracy. The immediate bleeding complications in all treatment groups were similar to those seen in the control group and were successfully managed with local hemostatic measures.

CONCLUSIONS: The antiplatelet effects of aspirin disappeared 96 hours after aspirin withdrawal in our study, and dental extractions may be safely performed in this period when appropriate local hemostatic measures are taken. Based on these results, a shorter aspirin intake cessation period may be allowable in complex dental procedures and surgery for which a longer aspirin intake cessation period (7-10 days) is recommended based on the American College of Chest Physicians guidelines.