Effects of pretreatment with clopidogrel on platelet and coagulation activation in patients undergoing elective coronary stenting

Effects of P2Y12 receptor inhibition with or without aspirin on hemostatic system activation: a randomized trial in healthy subjects

ESSENTIALS: In acute coronary syndromes, dual antiplatelet therapy inhibits platelets but confers a bleeding risk. Healthy male volunteers received clopidogrel or ticagrelor plus aspirin or clopidogrel or ticagrelor alone. The decrease in β-thromboglobulin in shed blood was comparable after single and dual antiplatelet therapy. We hypothesize that patients with acute coronary syndromes may not require dual antiplatelet therapy.

BACKGROUND

Dual antiplatelet therapy with a P2Y12 inhibitor and aspirin is standard in acute coronary syndromes. Dual antiplatelet therapy causes more bleeding than single antiplatelet therapy with a P2Y12 inhibitor.

OBJECTIVES

To compare the effects of dual and single antiplatelet therapies on hemostatic system activation.

PATIENTS/METHODS

In a randomized, parallel-group, double-blind, placebo-controlled study, 44 healthy volunteers received clopidogrel (600 mg, then 150 mg d(-1) ) and aspirin (100 mg d(-1) ) or placebo for 7 days; An additional 44 volunteers received single-dose ticagrelor (180 mg) and aspirin (300 mg) or placebo. β-Thromboglobulin (β-TG [IU L(-1) ]) and prothrombin fragment 1.2 (f1.2 [nmol L(-1) ]) were measured in blood obtained from bleeding time incisions. Data are given as geometric mean ratio (GMR [95% confidence interval]) to describe the differences in the first 2 h and as mean differences (Δ [95% confidence interval]) in area under the curve (AUC) to discriminate differences in effects over the total observation time.

RESULTS

Clopidogrel plus aspirin and clopidogrel plus placebo reduced β-TG by a GMR of 0.51 (0.42-0.63) and 0.54 (0.46-0.64) at 2 h. Ticagrelor plus aspirin and ticagrelor plus placebo decreased β-TG by a GMR of 0.38 (0.26-0.57) and 0.47 (0.31-0.72). Ticagrelor plus aspirin and ticagrelor plus placebo reduced f1.2 by a GMR of 0.58 (0.45-0.75) and 0.55 (0.38-0.80); clopidogrel did not. Over 24 h, no difference in β-TG occurred between clopidogrel plus aspirin and clopidogrel plus placebo (ΔAUC = -2.9 [-9.9 to 4.1]) or between ticagrelor plus aspirin and ticagrelor plus placebo (ΔAUC = -3.5 [-11.8 to 4.7]). No difference in f1.2 occurred between clopidogrel plus aspirin and clopidogrel plus placebo (ΔAUC = -4.2 [-10.2 to 1.8]) or between ticagrelor plus aspirin and ticagrelor plus placebo (ΔAUC = -3.6 [-10.9 to 3.7]).

CONCLUSIONS

P2Y12 inhibitor monotherapy and dual antiplatelet therapy inhibit hemostatic system activation to a comparable extent.

Effect of timing of clopidogrel administration on 30-day clinical outcomes: 300-mg loading dose immediately after coronary stenting versus pretreatment 6 to 24 hours before stenting in a large unselected patient cohort

BACKGROUND

The aim of our prospective multicenter Clopidogrel Registry was to evaluate the efficacy and safety of a 300-mg loading dose of clopidogrel at the time of ad hoc stenting in patients with suspected coronary artery disease who were not pretreated with clopidogrel for any reason, and to compare the 30-day clinical event rates with the outcome of patients pretreated with a loading dose of clopidogrel 6 to 24 hours before stenting.

METHODS

Between March 2002 and February 2004, 4160 consecutively included patients received a 300-mg loading dose of clopidogrel immediately after (group 1, n = 2679) or 6 to 24 hours before stenting (group 2, n = 1481).

RESULTS

The primary end point (triple composite end point of acute myocardial infarction, all-cause death, and urgent repeat target vessel revascularization) at 30 days occurred in 4.74% versus 2.77% in groups 1 and 2, respectively (P = .002). The secondary end point events, the stent thrombosis, occurred significantly more frequently in group 1, with a trend toward increase in incidence of death, target vessel revascularization, or need for glycoprotein IIb/IIIa antagonists during percutaneous coronary intervention. Pretreatment with clopidogrel was associated with more major bleeding (secondary safety end point) (0.41% vs 1.35% in groups 1 and 2, respectively; P = .001).

CONCLUSIONS

The results of our multicenter prospective Clopidogrel Registry demonstrate lower efficacy of a 300-mg loading dose of clopidogrel at the time of stenting compared with pretreatment 6 to 24 hours before percutaneous coronary intervention on the 30-day composite clinical end point in the large unselected patient cohort, which suggests the benefit of clopidogrel pretreatment in all incoming patients with suspected significant coronary artery disease scheduled for coronary angiography.

Clopidogrel increases expression of chemokines in peripheral blood mononuclear cells in patients with coronary artery disease: results of a double-blind placebo-controlled study

BACKGROUND

Chemokines and platelet activation are both important in atherogenesis. Platelet inhibitors are widely used in coronary artery disease (CAD), and we hypothesized that the platelet inhibitor clopidogrel could modify chemokines in CAD patients.

OBJECTIVES

We sought to investigate the effect of clopidogrel on the expression of chemokines and chemokine receptors in peripheral blood mononuclear cells (PBMC) in CAD patients.

PATIENTS/METHODS

Thirty-seven patients with stable angina were randomized to clopidogrel (n = 18) or placebo (n = 19). PBMC, blood platelets and plasma were collected at baseline and after 7-10 days in the patients, and in 10 healthy controls. mRNA levels of chemokines and chemokine receptors in PBMC were analyzed by ribonuclease protection assays and real-time reverse transcriptase polymerase chain reaction. Platelet activation was studied by flow cytometry.

RESULTS

(i) At baseline, the gene expression of the regulated on activation normally T-cell expressed and secreted (RANTES) chemokines and macrophage inflammatory peptide (MIP)-1beta in PBMC, the expression of CD62P and CD63 on platelets and the levels of platelet-derived microparticles (PMP) were elevated in angina patients comparing healthy controls; (ii) markers of platelet activation were either reduced (CD63) or unchanged (CD62P, PMP, beta-thromboglobulin) during clopidogrel therapy; (iii) in contrast, clopidogrel significantly up-regulated the gene expression of RANTES and MIP-1beta in PBMC, while no changes were found in the placebo group; (iv) a stable adenosine 5'-diphosphate metabolite attenuated the release of MIP-1beta, but not of RANTES, from activated PBMC in vitro.

CONCLUSIONS

Even if we do not argue against a beneficial role for clopidogrel in CAD, our findings may suggest potential inflammatory effects of clopidogrel in CAD.

Clopidogrel has no effect on D-dimer and thrombin-antithrombin III levels in patients with peripheral arterial disease undergoing peripheral percutaneous transluminal angioplasty

OBJECTIVE

Coagulation activation markers are significantly elevated in patients with peripheral arterial disease compared with healthy controls. The more severe the disease, the higher the markers. Increased coagulation activation may contribute to the disease process and the risk of complications in patients with peripheral arterial disease, particularly after endovascular intervention. Animal studies have shown that clopidogrel significantly inhibits coagulation activation. The aim of this study was to determine whether combination of aspirin and clopidogrel affects thrombin-antithrombin III and D-dimer in patients with intermittent claudication undergoing angioplasty, compared with aspirin alone.

METHODS

This was a double blind, randomized placebo-controlled trial conducted in a vascular unit in a tertiary referral center. One hundred thirty-two patients with intermittent claudication were randomized to clopidogrel and aspirin or placebo and aspirin, with a loading dose 12 hours before endovascular intervention. D-dimer and thrombin-antithrombin III (TAT) levels were measured using enzyme-linked immunosorbent assay at baseline, 1 hour before, and 1 hour, 24 hours, and 30 days after intervention in 103 patients who underwent endovascular intervention.

RESULTS

There was a significant rise in D-dimer levels at 1 hour and 24 hours after angioplasty in both groups (placebo group: 63.69, 141.45, 122.18 ng/mL; clopidogrel group: 103.79, 159.95, 134.69 ng/mL), but no difference between the two groups (P = .514). Similarly there was a significant rise in TAT levels at 1 hour after angioplasty in both groups (placebo group: 2.93, 6.16 microg/L; clopidogrel group: 3.39, 5.27 microg/L), with no significant difference between the two groups (P = .746).

CONCLUSION

Endovascular intervention results in a significant increase in TAT and D-dimer. The addition of clopidogrel to aspirin has no effect on TAT and D-dimer before or after endovascular intervention.

Clopidogrel administration prior to coronary artery bypass grafting surgery: the cardiologist's panacea or the surgeon's headache?

AIMS

Thrombotic complications after percutaneous coronary intervention procedures have decreased in past years mainly due to the use of clopidogrel antiplatelet therapy. However, the risk of bleeding due to enhanced and irreversible platelet inhibition in patients who will require surgical coronary revascularization instead has not been adequately addressed in the literature. The purpose of this study was to evaluate the effect of pre-operative clopidrogel exposure in haemorrhage-related re-exploration rates, peri-operative transfusion requirements, morbidity, and mortality in patients undergoing coronary artery bypass grafting (CABG) surgery.

METHODS AND RESULTS

A study population of 2359 patients undergoing isolated CABG between January 2000 and June 2002 was reviewed. Of these, 415 (17.6%) received clopidogrel prior to CABG surgery, and 1944 (82.4%) did not. A risk-adjusted logistic regression analysis was used to assess the association between clopidogrel pre-medication (vs. no) and haemostatic re-operation, intraoperative and post-operative blood transfusion rates, and multiple transfusions received. Haemorrhage-related pre-operative risk factors identified from the literature and those found significant in a univariate model were used. Furthermore, a sub-cohort, matched-pair by propensity scores analysis, was also conducted. The clopidogrel group had a higher likelihood of haemostatic re-operation [OR = 4.9, (95% CI, 2.63-8.97), P < 0.01], an increase in total packed red blood cell transfusions [OR = 2.2, (95% CI, 1.70-2.84), P < 0.01], multiple unit blood transfusions [OR = 1.9, (95% CI, 1.33-2.75), P < 0.01] and platelet transfusions [OR = 2.6, (95% CI, 1.95-3.56), P < 0.01]. Surgical outcomes and operative mortality [OR = 1.5, (95% CI, 0.36-6.51), P = 0.56] were not significantly different.

CONCLUSION

Pre-operative clopidogrel exposure increases the risk of haemostatic re-operation and the requirements for blood and blood product transfusion during, and after, CABG surgery.