Reversal of the anti‐platelet effects of aspirin and clopidogrel
2012; Elsevier BV; Volume: 10; Issue: 4 Linguagem: Inglês
10.1111/j.1538-7836.2012.04641.x
ISSN1538-7933
AutoresC. Li, J. Hirsh, Chang Chun Xie, Marilyn Johnston, John W. Eikelboom,
Tópico(s)Platelet Disorders and Treatments
ResumoJournal of Thrombosis and HaemostasisVolume 10, Issue 4 p. 521-528 ORIGINAL ARTICLEFree Access Reversal of the anti-platelet effects of aspirin and clopidogrel C. LI, C. LI Department of Cardiology, First Affiliated Hospital of Nanjing Medical University, Nanjing, ChinaSearch for more papers by this authorJ. HIRSH, J. HIRSH Department of Medicine, MacMaster University, Hamilton, ONSearch for more papers by this authorC. XIE, C. XIE Population Health Research Institute, MacMaster University, Hamilton, ONSearch for more papers by this authorM. A. JOHNSTON, M. A. JOHNSTON Hemostasis Reference Laboratory, Henderson Hospital, Hamilton, ONSearch for more papers by this authorJ. W. EIKELBOOM, J. W. EIKELBOOM Thrombosis service, Hamilton General Hospital, Hamilton, ON, CanadaSearch for more papers by this author C. LI, C. LI Department of Cardiology, First Affiliated Hospital of Nanjing Medical University, Nanjing, ChinaSearch for more papers by this authorJ. HIRSH, J. HIRSH Department of Medicine, MacMaster University, Hamilton, ONSearch for more papers by this authorC. XIE, C. XIE Population Health Research Institute, MacMaster University, Hamilton, ONSearch for more papers by this authorM. A. JOHNSTON, M. A. JOHNSTON Hemostasis Reference Laboratory, Henderson Hospital, Hamilton, ONSearch for more papers by this authorJ. W. EIKELBOOM, J. W. EIKELBOOM Thrombosis service, Hamilton General Hospital, Hamilton, ON, CanadaSearch for more papers by this author First published: 23 January 2012 https://doi.org/10.1111/j.1538-7836.2012.04641.xCitations: 93 Chunjian Li, Department of Cardiology, First Affiliated Hospital of Nanjing Medical University, 300, Guangzhou Road, Nanjing 210029, China. Tel.: +86 25 83718836 6018; fax: +86 25 83674380. E-mail: lijay@njmu.edu.cn AboutSectionsPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Abstract Summary. Background: Guidelines recommend stopping aspirin and clopidogrel 7 to 10 days before surgery to allow time for replacement of permanently inhibited platelets by newly released uninhibited platelets.Objectives: The purpose of the present study was to determine the rate of offset of the anti-platelet effects of aspirin and clopidogrel after stopping treatment and the proportion of untreated donor platelets that are required to reverse their anti-platelet effects.Methods: Cohort 1 consisted of 15 healthy subjects who received aspirin 81 mg day−1 or clopidogrel 75 mg day−1 for 7 days and underwent serial blood sampling until platelet function testing results normalized. Cohort 2 consisted of 36 healthy subjects who received aspirin 325 mg day−1, clopidogrel 75 mg day−1, aspirin 81 mg day−1 plus clopidogrel 75 mg day−1 or no treatment for 7 days and underwent a single blood sampling.Results: In cohort 1, arachidonic acid (AA)-induced light transmission aggregation (LTA) returned to baseline levels in all subjects within 4 days of stopping aspirin, coinciding with the partial recovery of plasma thromboxane B2 concentrations. ADP-induced LTA did not return to baseline levels until 10 days after stopping clopidogrel. In cohort 2, AA-induced LTA in patient treated with aspirin reached control levels after mixing with 30% untreated donor platelets whereas ADP-induced LTA in patients treated with clopidogrel reached control levels only after the addition of 90% or more donor platelets.Conclusions: Platelet aggregation recovers within 4 days of stopping aspirin but clopidogrel must be stopped for 10 days to achieve a normal aggregatory response. Introduction Aspirin and clopidogrel are effective anti-platelet drugs for the prevention of cardiovascular events but are often stopped before surgery because they can cause bleeding [1, 2]. The timing of stopping anti-platelet treatment before procedures is important because prolonged discontinuation can increase the risk of ischemic events whereas delayed discontinuation can increase the risk of bleeding [3]. The American College of Chest Physicians and the American College of Cardiology/American Heart Association guidelines recommend stopping aspirin and clopidogrel 7 to 10 days before surgery [4, 5] based on their irreversible platelet-inhibitory effects and the premise that recovery of hemostatic function after stopping treatment requires the replacement of irreversibly inhibited platelets by newly synthesized uninhibited platelets released from the bone marrow. An alternative approach to stopping anti-platelet therapy before surgery might be to transfuse patients with uninhibited donor platelets [6, 7]. However, it is uncertain whether platelet transfusion can fully reverse the anti-platelet effects of aspirin and clopidogrel and, if so, the proportion of non-treated platelets required to reverse their effects. The first objective of the present study was to compare the time course of recovery of platelet function after stopping aspirin and clopidogrel treatment. The second objective was to determine the proportion of untreated donor platelets required to fully reverse the platelet inhibitory effects of aspirin and clopidogrel. Methods Study population We designed two cohort studies, and enrolled 51 healthy subjects aged at least 18 years who did not have a history of cardiovascular disease and were not taking anti-platelet therapy from January 2009 to July 2010 in Hamilton General Hospital, Hamilton, Canada. Exclusion criteria were (i) allergy or intolerance to aspirin or clopidogrel; (ii) subjects at a high risk of bleeding (e.g. thrombocytopenia [platelet count < 150 × 109 L−1]), known bleeding diathesis, active peptic ulcer disease; (iii) cigarette smoking; (iv) diabetes; (v) pregnancy; and (vi) consumption of drugs within the preceding week that potentially could interfere with the anti-platelet effects of aspirin (e.g. non-steroidal anti-inflammatory drugs) or clopidogrel (e.g. proton pump inhibitors). The study design is shown in Fig. 1. Figure 1Open in figure viewerPowerPoint Study design. The present study complies with the Declaration of Helsinki, and approved by the Research Ethics Board of Hamilton Health Science Corporation. All study subjects provided written informed consent. Cohort 1: recovery of platelet function after stopping aspirin and clopidogrel Study treatments Fifteen subjects were treated with either aspirin (PharmaScience Inc., Montreal, QC, Canada) 81 mg (n = 7) or clopidogrel (Sanofi-aventis, Paris, France) 75 mg (n = 8) taken once daily at 08.00 hours for 7 days. Blood and urine collection Venous blood samples were collected by venipuncture into two 4.5-mL draw vacutainer tubes (Becton, Dickinson and Company, Mississauga, Canada) containing 0.105 m buffered sodium citrate (3.2%), one 2-mL draw Greiner Bio-One vacuette (Accumetrics, San Diego, CA, USA) containing 0.105 m buffered sodium citrate (3.2%) and one 4-mL draw BD vacutainer tube without additive immediately before starting the study drug and on days 1 to 6, 8, 10, 12 and 14 after the last dose of the study drug. In patients treated with aspirin, 10 mL of urine was collected into a sterile tube simultaneously with the blood sampling, then transferred into a 2-mL tube and frozen at −80 °C until further analysis. Bleeding time For subjects treated with aspirin, bleeding time was measured using the Surgicutt® device (International Technidyne Corporation, Edison, NJ, USA) by a single operator (C. Li) on days 1, 3, 5, and 8 after the last dose of aspirin. Briefly, the volunteer's arm was placed on a table with the volar surface exposed. A blood pressure cuff was placed around the upper arm and inflated to 40 mmHg for the duration of the test. An area on the volar surface of the forearm was swabbed with alcohol and allowed to air dry. A single incision was made parallel to and 5 cm below the antecubital crease using the Surgicutt® device and the blood was blotted with filter paper every 30 s until bleeding stopped. Care was taken during the blotting not to touch the edge of the clot and wound. The time from the incision to the end of bleeding was measured. Laboratory analyzes Light transmittance aggregation (LTA) was performed in platelet-rich plasma using arachidonic acid (AA), ADP and collagen as agonists. All agonists were obtained from Chronolog (Havertown, PA, USA). In aspirin-treated subjects, we also assessed platelet function using the rapid platelet function assay (RPFA) aspirin cartridge (Accumetrics, San Diego, CA, USA) and we measured serum thromboxane B2 (TXB2), plasma TXB2 in platelet-rich plasma after AA aggregation and urinary 11-dehydro thromboxane B2 (11-dH-TXB2). Cohort 2: reversal of the anti-platelet effects of aspirin and clopidogrel using donor platelets Study treatments Eighteen healthy subjects received 7 days of treatment with aspirin (NovoPharm Limited, Scarborough, ON, Canada) 325 mg day−1 (n = 5); clopidogrel 75 mg day−1 (n = 7); or the combination of aspirin 81 mg day−1 and clopidogrel 75 mg day−1 (n = 6) taken at 20.00 hours each day. Another 18 healthy subjects received no anti-platelet therapy and served as controls. Blood collection Venous blood samples were collected by venipuncture into two 4.5-mL draw BD vacutainer tubes containing 0.105 m buffered sodium citrate (3.2%) at 08.00 hours in the morning after the last dose of the study drug. Laboratory analyzes Platelet-rich plasma (PRP) from subjects who received anti-platelet therapy was mixed with increasing proportions of PRP from untreated controls, with one untreated subject serving as the control for one treated subject. The proportion of control platelets mixed with inhibited platelets was calculated based on platelet numbers, starting at 10% and increasing by 10% increments. AA, ADP and collagen-induced platelet aggregation were measured before and after mixing. Plasma TXB2 concentrations were measured in PRP from subjects treated with aspirin and in those treated with the combination of aspirin and clopidogrel. Laboratory procedures Sample preparation PRP and platelet-poor plasma (PPP) were prepared shortly after blood collection by spinning the sample at 200 g for 8 min. The PRP was carefully removed and the remaining blood centrifuged at 2465 g for 10 min to obtain PPP. The centrifuge temperature was maintained at 22 °C. Platelet counts were adjusted by the addition of PPP to the PRP to achieve a count of 250 × 109 L−1. Platelet aggregation studies were completed within 3 h of preparation of PRP. Venous blood was allowed to clot in a warmed additive free BD vacutainer and then incubated at 37 °C for 1 h. The blood was spun at 2000 g for 15 min and the serum was removed from the cellular elements and stored at −80 °C until assayed for TXB2. Platelet aggregation Platelet aggregation studies were performed using a Chronolog 560VS/490-2D aggregometer (Chronolog Corporation, Havertown, PA, USA). Immediately after preparation of PRP, 500 μL was transferred into each of the three test tubes, with 500 μL PPP set as a control. After 2 min of warming, PRP and PPP were put in testing places and were warmed for a further 2 min. Final concentrations of agonists were: AA 1 mm, ADP 5 μm and collagen 1 μg mL−1, respectively. The aggregated plasma samples were stored at −80 °C until assayed for TXB2. Rapid platelet function assay The rapid platelet function assay (RPFA) is a semi-quantitative platelet function test which measures turbidimetric platelet aggregation as an increase of light transmittance as a result of platelet agglutination. The test was performed using the VerifyNow® AspirinWorks assay (Accumetrics) according to the manufacturer's instructions. Briefly, at the instrument prompt, a cartridge was inserted into the instrument with the needle's protection sheath removed. The Greiner Bio-one vacuette containing 2 mL of citrated venous blood was gently mixed and inserted onto the needle of the cartridge. Results were reported in aspirin reaction units (ARU), a function of the rate at which platelets aggregate. A result of < 550 ARU indicates an 'adequate' response to aspirin, whereas ≥ 550 ARU indicates an 'inadequate' or low response to aspirin. Serum and plasma TXB2 Serums and plasma TXB2 was analyzed using the Amersham Biotrak Thromboxane B2 ELISA kit (GE Healthcare, Montreal, Canada) according to the manufacturer's instructions. In-house controls were tested with each batch. Urinary 11-dH-TXB2 Urinary 11-dH-TXB2 was measured using a commercially available AspirinWorks enzyme immunoassay kit (Corgenix Inc., Broomfield, CO, USA) according to the manufacturer's instructions. This assay has an inter-assay and an intra-assay coefficient of variation of 5.8% and 3.7%, respectively. Kit urine controls with assigned values for 11-dH-TXB2 were tested with each batch. Statistical analyzes Results of categorical variables are presented as number and percentage and results of continuous variables as means ± standard deviations or median (interquartile range [IQR]) where appropriate. The statistical significance of differences in means and medians was analyzed using two-way analysis of variance or the Kruskal–Wallis rank test, and Dunnett's multiple comparison tests. The three-parameter logistic function was adopted to explore the relation between AA-induced platelet aggregation (PLAA) and plasma TXB2 concentration after stopping aspirin treatment. Recovery ratios of AA- and ADP-induced aggregation ([Xn-X1/baseline-X1] × 100%; Xn represent PLAA, PLADP of day 2–6, 8, 10 and 12 after aspirin and clopidogrel withdrawal; X1 represent AA- or ADP-induced aggregation on day 1 after aspirin and clopidogrel withdrawal; baseline represent AA- or ADP-induced platelet aggregation before taking aspirin and clopidogrel) after aspirin and clopidogrel withdrawal were compared using two-factor repeated measurements anova. Similarly, the recovery curves of plasma TXB2, serum TXB2 and urinary 11-dH-TXB2 after withdrawal of aspirin were compared with the recovery of AA-induced platelet aggregation (PLAA) after withdrawal of aspirin and with the recovery of ADP-induced platelet aggregation (PLADP) after the withdrawal of clopidogrel. All analyzes were performed using sas 9.1.3 (SAS Institute Inc., Cary, NC, USA) and Stata11 (StataCorp LP, College Station, TX, USA). A two-sided P-value < 0.05 was considered statistically significant. Results Key baseline characteristics of study subjects are presented in Table 1. Table 1. Subject basic characteristics Cohort 1 Cohort 2 Aspirin Clopidogrel Aspirin Control Clopidogrel Control Combination Control n 7 8 5 5 7 7 6 6 Males (%) 3 (43) 6 (75) 3 (60) 2 (40) 5 (71) 3 (43) 2 (33) 2 (33) Age (years) 39 ± 7 25 ± 1 36 ± 10 36 ± 9 38 ± 9 35 ± 9 43 ± 8 34 ± 8 Weight (kg) 77.4 ± 13.5 63.1 ± 6.1 73.9 ± 9.4 61.6 ± 5.9 64.1 ± 7.9 61.1 ± 9.0 77.4 ± 11.9 64.1 ± 6.1 Combination: aspirin and clopidogrel; kg, kilogram; n, number. Cohort 1: recovery of platelet function after stopping aspirin and clopidogrel Recovery of platelet function after stopping aspirin Compared with baseline levels, PLAA was maximally suppressed on day 1 after completion of aspirin treatment (2.4 ± 1.6% vs. 83.6 ± 4.6%, P < 0.0001) and remained fully inhibited on day 2. Platelet function began to recover on day 3 and returned to baseline levels by day 4 (84.6 ± 4.0% vs. 83.6 ± 4.6%, P = 1.0) (Fig. 2A). ADP and collagen-induced platelet aggregation also recovered to baseline levels within 4 days of the last dose of aspirin (Appendix 1). Figure 2Open in figure viewerPowerPoint Offset of the anti-platelet effects of aspirin (A) and clopidogrel (B). (A) Demonstrates recovery of AA-induced platelet aggregation (PLAA) and plasma thromboxane B2 (TXB2) (n = 7). (B) Demonstrates recovery of ADP-induced platelet aggregation (PLADP) (n = 8). Error bars represent two standard errors above and below the mean. Baseline indicates immediately before ingestion of the first dose of study drug. AA-induced platelet aggregation in whole blood as measured by RPFA was maximally suppressed on day 1 after the completion of aspirin treatment (503.7 ± 81.3 vs. 657.6 ± 8.7 ARU, P < 0.0001) and recovered to baseline level by day 4 (635.6 ± 25.2 vs. 657.6 ± 8.7 ARU, P = 0.80). Plasma TXB2 concentrations were maximally suppressed on day 1 after the completion of aspirin treatment (median: 6.5, IQR 4.5–19.4 vs. 1732.5, IQR 1343.7–1954.5 ng mL−1, P < 0.0001). Unlike the recovery of PLAA, plasma TXB2 levels did not recover to baseline levels until 10 days after the last dose of aspirin (1423.5, IQR 1310.9–1555.0 vs. 1732.5, IQR 1343.7–1954.5 ng mL−1, P = 0.56) (Fig. 2A). The pattern of recovery of serum TXB2 and urinary 11-dH-TXB2 was similar to that of plasma TXB2 with complete recovery not occurring until 8–10 days after completion of aspirin therapy (Appendix 2). The mean bleeding time increased from 352 ± 126 to 472 ± 142 s (P = 0.03) on day 1 after completion of aspirin therapy. Bleeding time was not measured on day 4 but by day 5 had returned to baseline levels (318 ± 101 vs. 352 ± 126 s, P = 0.82). A plot of PLAA and plasma TXB2 after stopping aspirin treatment revealed a symmetric sigmoid relation with abrupt recovery of PLAA in all subjects when plasma TXB2 levels exceeded 400 ng mL−1. Median PLAA was achieved at a plasma TXB2 level of 387 ng mL−1, which is equivalent to the EC50 value (Appendix 3). Recovery of platelet function after stopping clopidogrel PLADP was maximally inhibited on day 1 after completion of clopidogrel treatment (24.6 ± 11.1% vs. 73.8 ± 7.6%, P < 0.0001) and full recovery did not occur until day 10 (72.0 ± 9.6% vs. 73.8 ± 7.6%, P = 1.0) (Fig. 2B). Comparison of the recovery curves between PLAA and plasma TXB2, serum TXB2, urinary 11-dH-TXB2 after stopping aspirin, and PLADP after stopping clopidogrel The recovery of PLAA after stopping aspirin was significantly more rapid than that of plasma TXB2 (P < 0.0001), serum TXB2 (P < 0.0001) and urinary 11-dH-TXB2 (P = 0.0023), and the recovery of PLADP after stopping clopidogrel (P = 0.0086). In contrast, the recovery curves of PLADP after stopping clopidogrel were similar to that of plasma TXB2, serum TXB2 and urinary 11-dH-TXB2 after stopping aspirin (P = 0.64, 0.18 and 0.86, respectively). Cohort 2: reversal of the anti-platelet effects of aspirin and clopidogrel using donor platelets Reversal of the anti-platelet effects of aspirin Among subjects treated with aspirin, suppression of PLAA was fully reversed compared with controls after mixing with 30% uninhibited control platelets (84.4 ± 9.1% vs. 78.4 ± 13.7%, P = 0.99) (Fig. 3A). A similar reversal pattern was evident for collagen and ADP-induced platelet aggregation (Appendix 4). In contrast, plasma TXB2 concentrations did not approximate control levels until all the platelets were replaced by the uninhibited donor platelets (Fig. 3A). Figure 3Open in figure viewerPowerPoint Reversal of the anti-platelet effects of aspirin (A), clopidogrel (B) and the combination of aspirin and clopidogrel (C and D) compared with controls. (A) Demonstrates reversal of AA-induced platelet aggregation (PLAA) and plasma thromboxane B2 (TXB2) (n = 5 pairs). (B) Demonstrates reversal of ADP-induced platelet aggregation (PLADP) (n = 7 pairs). (C) Demonstrates reversal of PLAA and plasma TXB2 (n = 6 pairs). (D) Demonstrates reversal of PLADP (n = 6 pairs). Error bars represent two standard errors above and below the mean. Reversal of the anti-platelet effects of clopidogrel Among subjects treated with clopidogrel, suppression of PLADP was fully reversed only after mixing with 90% or more uninhibited donor platelets (75.7 ± 9.6% vs. 76.0 ± 15.5%, P = 1.00) (Fig. 3B). Reversal of the anti-platelet effects of the combination of aspirin and clopidogrel Among subjects treated with the combination of aspirin and clopidogrel, suppression of PLAA was fully reversed compared with controls after adding 20% donor platelets (73.7 ± 13.9% vs. 84.3 ± 4.8%, P = 0.57) (Fig. 3C). Plasma TXB2 was fully inhibited to 15.84 ng mL−1 and did not return to control levels (1545.50 ng mL−1) until all the platelets were replaced by the donor platelets (Fig. 3C). Similarly, PLADP was fully reversed only after the addition of 90% or more donor platelets (Fig. 3D). Discussion The present results indicate that the patterns of recovery of thromboxane production after stopping aspirin and of PLADP after stopping clopidogrel are similar, with full recovery taking approximately 10 days. In contrast, the recovery of PLAA after stopping aspirin is much more rapid, with complete recovery occurring within 4 days. Differences between aspirin and clopidogrel in the rate of recovery of platelet aggregation after stopping treatment are paralleled by differences in the proportion of untreated control platelets required in mixing studies to reverse their anti-platelet effects, where reversal of inhibition of AA-induced aggregation by aspirin is achieved when the mixture contains 30% non-aspirinated platelets whereas inhibition of PLADP is achieved when the mixture contains at least 90% uninhibited platelets. The similar patterns of recovery of thromboxane production after stopping aspirin and of PLADP after stopping clopidogrel are explained by the irreversible platelet-inhibitory effects of the drugs. Aspirin permanently inhibits the cyclooxygenase activity of prostaglandin H-synthase-1 (also referred to as COX-1), thereby blocking platelet thromboxane production [8], and the active metabolite of clopidogrel permanently inhibits the platelet P2Y12 receptor, thereby blocking ADP-induced platelet aggregation [9]. Full recovery of platelet thromboxane production and PLADP does not occur until permanently inhibited platelets are replaced by de novo newly synthesized platelets, usually after 10 days (When platelet turnover is normal, approximately 10% of platelets are replaced each day [10]). The recovery of PLAA 4 days after stopping aspirin coincides with the replacement of approximately 40% of aspirinated platelets with newly released non-aspirinated platelets. This finding is consistent with in vitro mixing studies that demonstrated reversal of PLAA when the mixture contained only 30% non-aspirinated platelets. Both lines of evidence indicate that in aspirin-treated subjects, only 30% to 40% uninhibited platelets are required to produce sufficient thromboxane A2 to achieve a normal aggregation response, by activating the thromboxane A2 receptor of their own and the adjacent aspirinated platelets. Thromboxane from non-platelet sources (e.g. monocytes, endothelial cells) can also stimulate platelets in the presence of aspirin because aspirin selectively blocks COX-1 and does not inhibit the platelet thromboxane receptor [8]. Our results demonstrating rapid recovery of platelet function after stopping aspirin are consistent with those reported by Zisman et al. [11] who found that PLAA normalized within 3 days of stopping aspirin and by Feldman et al. [12] who reported that serum TXB2 levels remained suppressed for at least 7 days after stopping aspirin. Likewise, delayed recovery of PLADP after stopping clopidogrel in the present study is similar to the rate of recovery reported in other studies as measured using the VerifyNow® P2Y12 assay [13] and bleeding time [14]. However, none of these previous studies explored the effects of mixing with uninhibited platelets on the platelet inhibitory effects of aspirin and clopidogrel. The present results have potential implications for the peri-operative management of aspirin and clopidogrel. First, if normal hemostasis is required, stopping of aspirin for 4 days and clopidogrel for 10 days before surgery should ensure full recovery of the platelet aggregation response. Second, it seems reasonable to expect that the dose of platelets required to reverse the anti-aggregatory effects of aspirin is lower than the dose required to reverse the anti-aggregatory effects of clopidogrel. However, the present study cannot provide guidance on the dose of platelets that may be required because our observations are based on in vitro-mixing studies. Third, bleeding in patients receiving dual anti-platelet therapy with a combination of aspirin and clopidogrel is of particular concern in those who require urgent cardiac or non-cardiac surgery [3, 15]. Some of these patients are also at a high risk for thromboembolic events, for example stent thrombosis [15]. In such patients, one option to optimize the risk/benefit ratio might be to stop clopidogrel 5 or more days before surgery, but to continue aspirin until the time of surgery and to transfuse platelets immediately before surgery to fully reverse the anti-platelet effects of aspirin. This approach requires testing in clinical studies. The present study has potential limitations. First, the number of subjects was small and we included only healthy controls. However, in post hoc sample size calculations (based on means and standard deviations observed in our study) we have confirmed that our sample size provides at least 80% power to demonstrate a significant difference between inhibited and uninhibited platelets (as measured by platelet aggregation testing) at a given time point, even after adjustment for multiple testing; and there is no reason to expect different results in patients with established cardiovascular disease [11, 13] compared with healthy controls. Second, although our data provide the best available evidence to date for the rate of recovery of platelet function after stopping aspirin and clopidogrel and the reversal of their antiplatelet effects using uninhibited platelets, there are only limited data on the association between in vitro platelet function and clinical events. In conclusion, aspirin permanently inhibits platelet thromboxane production and clopidogrel permanently inhibits PLADP for the life of the platelet. The platelet aggregation response to AA recovers within 4 days of stopping aspirin, whereas the platelet aggregation response to ADP recovers within 10 days of stopping clopidogrel. These findings are paralleled by the observations in in vitro mixing experiments that the platelet inhibitory effects of aspirin are reversed with 30% non-aspirinated platelets in the mixture, compared with the requirement for at least 90% uninhibited platelets in the mixture to completely reverse the anti-platelet effects of clopidogrel. The effect of clopidogrel on platelet function lasts longer than that of aspirin because thromboxane from non-aspirinated platelets is able to activate aspirinated platelets whereas platelets that are still inhibited by the active metabolite of clopidogrel do not aggregate normally in response to ADP. Based on the present results, stopping aspirin for 7–10 days is longer than required for the recovery of platelet function in patients treated with aspirin and is sufficient for the recovery of platelet function in patients treated with clopidogrel. Acknowledgements This work was carried out in the Thrombosis service, Hamilton General Hospital, Hamilton, Ontario, Canada. This work was supported by a grant from the New Investigator Funding of Hamilton Health Science (NIF-08200[R]), Hamilton, Canada, and a grant from the National Natural Science Funding of China (81170181). Disclosure of Conflict of Interests The authors state that they have no conflict of interest. Appendices Appendix 1 Offset of the anti-platelet effects of 7-day aspirin and clopidogrel treatment (Cohort 1). Recovery aspirin (n = 7) Recovery clopidogrel (n = 8) BT (s) RPFA (ARU) PLAA (%) PLADP (%) PLCOLL (%) Plasma TXB2 (ng mL−1) Serum TXB2 (ng mL−1) Urinary 11-dH-TXB2 (ng mL−1) PLAA (%) PLADP (%) PLCOLL (%) Before treatment 5.9 ± 2.1 657.6 ± 8.7 83.6 ± 4.6 76.1 ± 5.6 80.3 ± 11.9 1649.6 ± 347.7 197.0 ± 164.6 273.0 ± 158.0 72.4 ± 2.8 73.8 ± 7.6 67.1 ± 12.6 Day 1 7.9 ± 2.4 503.7 ± 81.3 2.4 ± 1.6 61.9 ± 7.6 40.6 ± 18.5 38.7 ± 82.6 3.9 ± 7.9 64.2 ± 40.8 59.1 ± 8.6 24.6 ± 11.0 43.2 ± 11.8 Day 2 – 524.9 ± 73.2 2.1 ± 1.3 60.9 ± 7.3 54.1 ± 20.6 86.7 ± 132.0 19.8 ± 11.6 83.9 ± 38.2 59.8 ± 10.0 30.2 ± 18.1 53.2 ± 12.8 Day 3 7.7 ± 1.4 589.7 ± 49.4 14.7 ± 35.9 61.2 ± 11.6 56.5 ± 19.1 217.8 ± 156.6 15.3 ± 3.3 110.7 ± 62.2 62.6 ± 6.9 34.3 ± 14.3 60.9 ± 8.7 Day 4 – 635.6 ± 25.2 84.6 ± 4.0 67.1 ± 6.4 77.4 ± 8.1 642.3 ± 180.2 45.2 ± 13.4 126.6 ± 44.2 65.6 ± 6.7 45.8 ± 13.6 59.1 ± 4.9 Day 5 5.3 ± 1.7 640.3 ± 30.2 82.3 ± 5.6 77.1 ± 11.3 77.9 ± 9.6 734.0 ± 255.7 70.8 ± 37.9 133.0 ± 31.0 68.4 ± 3.6 59.8 ± 13.5 64.8 ± 6.7 Day 6 – – 83.2 ± 3.8 78.3 ± 7.1 83.5 ± 6.8 1022.4 ± 217.0 100.2 ± 69.3 175.2 ± 64.4 70.8 ± 4.2 61.1 ± 9.3 65.5 ± 8.3 Day 8 4.5 ± 1.2 – 86.2 ± 4.4 73.7 ± 13.2 86.5 ± 3.8 1227.4 ± 258.9 168.9 ± 110.7 309.5 ± 170.2 69.9 ± 6.3 61.4 ± 17.8 64.8 ± 6.6 Day 10 – – 84.8 ± 5.2 76.2 ± 7.1 84.3 ± 4.2 1448.6 ± 204.8 215.7 ± 124.5 328.8 ± 283.4 72.1 ± 4.9 72.0 ± 9.6 67.9 ± 9.5 Day 12 – – 84.5 ± 2.4 81.0 ± 4.6 86.7 ± 6.2 1756.6 ± 302.5 240.5 ± 138.7 342.1 ± 188.9 71.8 ± 5.7 74.4 ± 9.2 72.5 ± 5.2 Day 14 – – 87.4 ± 9.2 72.4 ± 14.4 80.0 ± 5.8 1738.2 ± 341.7 192.2 ± 81.4 304.3 ± 81.0 – – – Data are expressed as mean ± standard deviation. Recovery aspirin indicates recovery of the anti-platelet effects of aspirin; Recovery clopidogrel indicates recovery of the anti-platelet effects of clopidogrel. BT, bleeding time. Appendix 2 Recovery of serum TXB2 and urinary 11-dH-TXB2 after stopping aspirin treatment (n = 7). Error bars represent 2 standard errors above and below the mean. Baseline indicates immediately prior to ingestion of the first dose of aspirin. Appendix 3 Relation between PLAA and plasma TXB2 concentration after stopping aspirin treatment. Appendix 4 Reversal of the anti-platelet effects of 7-day aspirin and/or clopidogrel treatment by control platelets (Cohort 2). Con-PRP/Stu-PRP (v/v) Reversal aspirin (n = 5 + 5) Reversal clopidogrel (n = 7 + 7) Reversal aspirin and clopidogrel (n = 6 + 6) PLAA (%) PLADP (%) PLCOLL (%) Plasma TXB2 (ng mL−1) PLAA (%) PLADP (%) PLCOLL (%) PLAA (%) PLADP (%) PLCOLL (%) Plasma TXB2 (ng mL−1) 0/1.0 4.0 ± 0.7 62.0 ± 8.3 22.4 ± 7.3 11.3 ± 19.9 58.1 ± 30.0 22.6 ± 9.4 70.3 ± 16.7 4.2 ± 1.2 44.7 ± 7.5 18.7 ± 10.8 15.8 ± 19.1 0.1/0.9 34.0 ± 44.8 68.6 ± 12.6 44.0 ± 17.3 143.2 ± 100.4 74.0 ± 12.8 29.4 ± 9.3 75.4 ± 12.6 32.8 ± 34.6 48.2 ± 6.5 33.2 ± 18.2 147.6 ± 42.6 0.2/0.8 63.0 ± 38.1 71.2 ± 15.3 64.2 ± 17.7 305.1 ± 97.2 80.9 ± 8.0 37.0 ± 12.0 77.0 ± 6.9 73.7 ± 13.9 52.0 ± 5.9 57.8 ± 10.7 372.6 ± 69.1 0.3/0.7 84.4 ± 9.1 75.8 ± 13.0 64.8 ± 19.7 524.6 ± 127.7 81.6 ± 3.6 45.4 ± 10.0 76.3 ± 9.4 81.3 ± 6.0 55.7 ± 10.1 66.0 ± 9.1 532.9 ± 74.3 0.4/0.6 86.0 ± 9.2 79.6 ± 13.9 71.8 ± 11.8 – 80.9 ± 5.6 54.7 ± 14.5 83.0 ± 7.9 83.7 ± 2.3 61.8 ± 8.4 77.2 ± 7.2 – 0.5/0.5 86.8 ± 8.7 79.0 ± 17.2 75.2 ± 18.9 862.0 ± 195.0 83.3 ± 6.0 57.1 ± 12.1 85.0 ± 8.1 84.3 ± 4.1 66.5 ± 8.0 77.2 ± 3.4 841.6 ± 142.7 0.6/0.4 86.8 ± 10.1 77.4 ± 15.2 75.8 ± 14.2 – 82.6 ± 5.4 63.3 ± 10.0 82.1 ± 4.3 83.8 ± 5.8 67.8 ± 9.2 75.2 ± 1.8 – 0.7/0.3 – – – – 85.6 ± 4.1 71.6 ± 10.3 85.1 ± 4.7 86.7 ± 4.8 74.3 ± 7.6 82.0 ± 4.2 – 0.8/0.2 85.0 ± 11.2 73.8 ± 8.4 80.0 ± 11.9 1350.5 ± 573.6 83.4 ± 5.4 68.4 ± 11.1 82.1 ± 4.3 87.5 ± 5.0 74.3 ± 8.7 82.2 ± 6.5 1240.1 ± 179.2 0.9/0.1 – – – – 85.0 ± 5.7 75.7 ± 9.6 83.4 ± 6.6 86.7 ± 5.4 77.7 ± 6.7 83.7 ± 2.6 – 1.0/0 78.4 ± 13.7 70.6 ± 7.5 81.0 ± 7.1 1826.5 ± 237.5 85.6 ± 7.5 76.0 ± 15.5 82.4 ± 10.6 84.3 ± 4.8 79.2 ± 6.6 88.3 ± 7.1 1545.5 ± 196.2 Data are expressed as mean ± standard deviation. Reversal aspirin indicates reversal of the anti-platelet effects of aspirin; Reversal clopidogrel indicates reversal of the anti-platelet effects of clopidogrel; Reversal aspirin and clopidogrel indicates reversal of the anti-platelet effects of aspirin and clopidogrel. Con-PRP, control platelet-rich plasma; Stu-PRP, study platelet-rich plasma. References 1 Alghamdi AA, Moussa F, Fremes SE. Does the use of preoperative aspirin increase the risk of bleeding in patients undergoing coronary artery bypass grafting surgery? Systematic review and meta-analysis. J Card Surg 2007; 22: 247– 56. Wiley Online LibraryPubMedWeb of Science®Google Scholar 2 Badreldin A, Kroener A, Kamiya H, Lichtenberg A, Hekmat K. Effect of clopidogrel on perioperative blood loss and transfusion in coronary artery bypass graft surgery. Interact Cardiovasc Thorac Surg 2010; 10: 48– 52. CrossrefPubMedWeb of Science®Google Scholar 3 Fitchett D, Eikelboom J, Fremes S, Mazer D, Singh S, Bittira B, Brister S, Graham JJ, Gupta M, Karkouti K, Lee A, Love M, McArthur R, Peterson M, Verma S, Yau TM. Dual antiplatelet therapy in patients requiring urgent coronary artery bypass grafting surgery: a position statement of the Canadian Cardiovascular Society. Can J Cardiol 2009; 25: 683– 9. CrossrefCASPubMedWeb of Science®Google Scholar 4 Douketis JD, Berger PB, Dunn AS, Jaffer AK, Spyropoulos AC, Becker RC, Ansell J. The perioperative management of antithrombotic therapy: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th Edition). Chest 2008; 133: 299S– 339S. CrossrefCASPubMedWeb of Science®Google Scholar 5 Eagle KA, Guyton RA, Davidoff R, Edwards FH, Ewy GA, Gardner TJ, Hart JC, Herrmann HC, Hillis LD, Hutter AM Jr, Lytle BW, Marlow RA, Nugent WC, Orszulak TA. ACC/AHA 2004 guideline update for coronary artery bypass graft surgery: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Committee to Update the 1999 Guidelines for Coronary Artery Bypass Graft Surgery). Circulation 2004; 110: e340– 437. CrossrefPubMedGoogle Scholar 6 Kapetanakis EI, Medlam DA, Boyce SW, Haile E, Hill PC, Dullum MK, Bafi AS, Petro KR, Corso PJ. Clopidogrel administration prior to coronary artery bypass grafting surgery: the cardiologist's panacea or the surgeon's headache? Eur Heart J 2005; 26: 576– 83. CrossrefCASPubMedWeb of Science®Google Scholar 7 Maltais S, Perrault LP, Do QB. Effect of clopidogrel on bleeding and transfusions after off-pump coronary artery bypass graft surgery: impact of discontinuation prior to surgery. Eur J Cardiothorac Surg 2008; 34: 127– 31. CrossrefPubMedWeb of Science®Google Scholar 8 Hankey GJ, Eikelboom JW. Aspirin resistance. Lancet 2006; 367: 606– 17. CrossrefCASPubMedWeb of Science®Google Scholar 9 Krotz F, Sohn HY, Klauss V. Antiplatelet drugs in cardiological practice: established strategies and new developments. Vasc Health Risk Manag 2008; 4: 637– 45. CrossrefPubMedGoogle Scholar 10 Leeksma CH, Cohen JA. Determination of the life of human blood platelets using labelled diisopropylfluorophosphanate. Nature 1955; 175: 552– 3. CrossrefCASPubMedWeb of Science®Google Scholar 11 Zisman E, Erport A, Kohanovsky E, Ballagulah M, Cassel A, Quitt M, Pizov R. Platelet function recovery after cessation of aspirin: preliminary study of volunteers and surgical patients. Eur J Anaesthesiol 2010; 27: 617– 23. CrossrefPubMedWeb of Science®Google Scholar 12 Feldman M, Shewmake K, Cryer B. Time course inhibition of gastric and platelet COX activity by acetylsalicylic acid in humans. Am J Physiol Gastrointest Liver Physiol 2000; 279: G1113– 20. CrossrefCASPubMedWeb of Science®Google Scholar 13 Gurbel PA, Bliden KP, Butler K, Tantry US, Gesheff T, Wei C, Teng R, Antonino MJ, Patil SB, Karunakaran A, Kereiakes DJ, Parris C, Purdy D, Wilson V, Ledley GS, Storey RF. Randomized double-blind assessment of the ONSET and OFFSET of the antiplatelet effects of ticagrelor versus clopidogrel in patients with stable coronary artery disease: the ONSET/OFFSET study. Circulation 2009; 120: 2577– 85. CrossrefCASPubMedWeb of Science®Google Scholar 14 Thebault JJ, Kieffer G, Lowe GD, Nimmo WS, Cariou R. Repeated-dose pharmacodynamics of clopidogrel in healthy subjects. Semin Thromb Hemost 1999; 25(Suppl 2): 9– 14. CASPubMedWeb of Science®Google Scholar 15 Kiran U, Makhija N. Patient with recent coronary artery stent requiring major non cardiac surgery. Indian J Anaesth 2009; 53: 582– 91. PubMedGoogle Scholar Citing Literature Volume10, Issue4April 2012Pages 521-528 FiguresReferencesRelatedInformation
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