Clopidogrel Resistance in Patients With Stroke Recurrence Under Single or Dual Antiplatelet Treatment

Background: The factors associated with clopidogrel resistance in patients with stroke recurrence receiving single or dual antiplatelet treatment (SAPT or DAPT) may differ. This study compared the high on-treatment platelet reactivities (HPRs) and the factors associated with clopidogrel resistance in recurrent ischemic stroke patients receiving clopidogrel or aspirin and clopidogrel.

Methods: We enrolled and allocated 275 recurrent ischemic stroke patients to the clopidogrel and DAPT groups and compared their demographics, conventional risk factors, and P2Y12 reaction units (PRUs). Clopidogrel resistance was categorized as PRU higher than 275. We performed a multivariate logistic regression analysis to determine the factors underlying clopidogrel resistance during SAPT and DAPT.

Results: In total, 145 (52.7%) and 130 (47.3%) patients received clopidogrel and DAPT, respectively at recurrence. The risk factors of the two groups were not significantly different, except that coronary artery disease was more frequent in the DAPT group. The PRU was higher (255 ± 91 vs. 221 ± 84; p = 0.002) and clopidogrel resistance was more frequent (45.5 vs. 31.5%; p = 0.018) in the SAPT than in the DAPT group. Hyperlipidemia was associated with clopidogrel resistance during SAPT, and smoking (Odds ratio = 0.426, 95% confidence interval 0.210–0.861; p = 0.018) had a protective effect against clopidogrel resistance. For those receiving DAPT, old age, female, low hemoglobin A1c level, and high ARU were associated with clopidogrel resistance.

Conclusions: HPR and clopidogrel resistance were more frequent in recurrent ischemic stroke patients receiving clopidogrel than in those receiving DAPT. Smoking was independently associated with less clopidogrel resistance among those receiving clopidogrel SAPT but not in those receiving DAPT.

Ticagrelor versus clopidogrel for prevention of subclinical stent thrombosis detected by optical coherence tomography in patients with drug-eluting stent implantation-a multicenter and randomized study

Introduction: This prospective, multicenter, randomized study was designed to analyze the benefits of ticagrelor over clopidogrel in reducing subclinical stent thrombosis (ST) in patients with coronary artery disease who underwent implantation of a second-generation drug-eluting stent (DES).Methods: About 352 patients with single de novo coronary stenosis were randomly assigne`d to either clopidogrel group (aspirin plus clopidogrel) or ticagrelor group (aspirin plus ticagrelor) after DES implantation for 1 year. Baseline clinical characteristics, blood chemistry markers, coronary artery angiography (CAG), and optical coherence tomography (OCT) were obtained during the index procedure. Data about clinic, CAG and OCT were also collected after 1 year follow-up. Intention-to-treat (ITT), per protocol set (PPS), and sensitivity analysis of subclinical ST were performed. Major factors associated with subclinical ST were analyzed by multivariable and univariable logistic regression models.Results: The incidence of subclinical ST in ticagrelor group was significantly low as compared to clopidogrel group (P < .05) at 1-year follow-up. Ticagrelor use was an independent factor in reducing subclinical ST (P < .05). The percentage of endothelial coverage, neointimal hyperplasia, malapposition, and edge dissection about stents were not different between the two groups (P > .05). Bleeding ratio was not markedly altered after ticagrelor treatment (P > .05). Not any significant differences were detected with regard to baseline clinical characteristics, CAG results, and DES between ticagrelor and clopidogrel groups (P > .05).Conclusion: In patients who underwent a second-generation DES implantation, using aspirin plus ticagrelor was associated with a significant reduction in subclinical ST. (ClinicalTrials.gov. Number: NCT02140801).

Predictors of strut coverage of drug eluting stent implantation in diabetic patients

BACKGROUND

Incomplete re-endothelialization of drug eluting stent (DES) segments has been associated with the occurrence of major adverse cardiac events after DES implantation. It is unknown whether on-clopidogrel platelet reactivity (OPR) and/or circulating endothelial progenitor cells (EPC) levels may predict uncovered strut rate in diabetic patients treated by DES implantation.

METHODS

One-hundred and five diabetic patients undergoing elective DES implantation were included into the study. EPC levels and OPR were assessed at 24 h (baseline) and 3 months. EPC were evaluated by flow cytometric analysis and defined by the co-expression of the markers CD34 and KDR. OPR was assessed using the impedance aggregometer. The degree of DES re-endothelialization was assessed at 3 months by optical coherence tomography.

RESULTS

A direct correlation was observed between the uncovered strut rate and OPR both at baseline (r = 0.47: p < 0.001) and at the 3 months (r = 0.25: p = 0.015). On the contrary, we found no significant correlation between EPC level and uncovered strut rate either at baseline (r = -0.02; p = 0.85) or at 3 months (r = -0.06; p = 0.13). By multivariable regression analysis, independent predictors of uncovered strut rate > 5% were complex lesions (OR = 5.35; 95% confidence interval 1.32-17.57; p = 0.027) and OPR at baseline (OR = 4.73; 95% confidence interval 1.04-8.14; p = 0.039).

CONCLUSIONS

In diabetic patients treated with DES implantation OPR at baseline and complex lesions are independent predictors of uncovered strut rate at 3 months.

Incidence and Morphological Predictors of Intrastent Coronary Thrombus After Drug-Eluting Stent Implantation (from a Multicenter Registry)

The mechanisms responsible for late and very late stent thrombosis remain incompletely understood. This study aimed to evaluate the incidence and morphologic predictors of intrastent thrombus in patients after drug-eluting stent (DES) implantation using optical coherence tomography (OCT). A total of 208 patients with 262 DES who underwent follow-up OCT examination >6 months after DES implantation were included. The detailed vascular morphology including characteristics of neointima was analyzed. Thrombus was identified in 24 patients (11.5%) 11 months after DES implantation. Minimal lumen cross-sectional area was significantly smaller in the thrombus group than in the nonthrombus group (2.9 ± 1.7 vs 4.6 ± 2.0 mm(2); p <0.001). No difference was found in the frequency of uncovered or malapposed struts between the 2 groups. Thin-cap fibroatheroma (20.6% vs 0.1%; p <0.001) and heterogeneous neointima (22.2% vs 9.0%; p = 0.001) were more frequently detected in the thrombus group compared to the nonthrombus group. Second-generation DES showed lower incidence of thrombus, uncovered struts, and extrastent lumen compared with first-generation DES. In conclusion, the present OCT study revealed that smaller lumen cross-sectional area and neointimal morphology are important factors associated with intrastent thrombus. Second-generation DES demonstrated improved arterial healing and a lower incidence of intrastent thrombus compared with first-generation DES.

Genetic testing and antiplatelet treatment: Still way to go?

Despite medical and technical advancements stent thrombosis continued to poses a significant risk in patients after drug eluting stent (DES) implantation and clopidogrel resistance has been recognized as an important determinant of this risk. Novel antiplatelets such as prasugrel and ticagrelor can be used in cases of clopidogrel resistance however bleeding complications remain the Achilles' heel of antiplatelet therapy. Several genetic polymorphisms affect the clopidogrel absorption and bio-activation in the active form of the drug. CYP2C19 is responsible for most of the clopidogrel bio-transformation and loss of function as well as, gain of function polymorphisms of this enzyme has been recognized. Early studies have linked CYP2C19 genetic polymorphisms with clinical events, although, these findings were not confirmed by later studies. However, when the estimated thrombotic risk is high a combination of genetic information and functional platelet tests should be essential for clinicians to access clopidogrel effectiveness and to recommend alternative antiplatelet management.