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

Multi-institutional patterns of clopidogrel response among patients undergoing transcarotid artery revascularization

OBJECTIVE

Current guidelines recommend dual antiplatelet therapy (DAPT) in patients undergoing carotid artery stenting. The most common DAPT regimen is aspirin and clopidogrel, a P2Y12 receptor antagonist; however, the prevalence of clopidogrel resistance (CR) in patients undergoing percutaneous coronary interventions may exceed 60%. Few studies have investigated the prevalence and impact of CR in patients undergoing extracranial carotid artery stenting, particularly transcarotid artery revascularization (TCAR).

METHODS

Consecutive high-risk patients ≥ 18 years who underwent TCAR for high grade (≥70%) and/or symptomatic (≥50%) carotid stenosis with preoperative P2Y12 testing between August 2019 and December 2021 were identified across five institutions. Preoperative platelet reactivity was measured with the VerifyNow P2Y12 Reaction Unit (PRU) Test (Instrumentation Laboratory, Bedford, MA), with CR defined as PRU ≥ 194 and hyper-response as PRU <70. Patients without preoperative P2Y12 testing within 30 days prior to TCAR or those on a non-clopidogrel P2Y12 inhibitor preoperatively were excluded. The primary outcome of interest was prevalence of CR. Secondary outcomes of interest included the incidence of ischemic and hemorrhagic complications.

RESULTS

Of 92 patients identified, the majority were male (59%) and Caucasian (75%) with a mean age of 75 years (±8, range 56-92). Preoperatively, 93% of patients were on aspirin, 100% on clopidogrel, and 13% on therapeutic anticoagulation. At presentation, 36% were symptomatic. The mean preoperative P2Y12 was 156 PRU (±76, range 6-349). In total, 30 (33%) patients met criteria for CR (mean PRU 240 ± 37; range 197-349), and 15 (16%) met criteria for hyper-responder (mean PRU 38 ± 20; range 6-68). There was no significant difference by clopidogrel response phenotype in terms of sex (p = 0.246), race (p = 0.384), or symptomatic presentation (p = 0.956). Postoperatively, the cumulative incidence of stroke and MI was 2.1%, with no statistically significant difference in the incidence of in-hospital stroke (PRU 238, p = 0.489) or MI (PRU 168, p = 1) between clopidogrel phenotypes. Three (3.3%) patients, one CR (PRU 240) and two responders (PRU 119 and PRU 189), experienced postoperative access site hematomas that required no subsequent intervention. No other index hospitalization hemorrhagic complications occurred.

CONCLUSIONS

Using preoperative P2Y12 testing with a threshold PRU ≥ 194 to define CR, we identified a high prevalence of CR in patients undergoing TCAR similar to that in the pre-existing coronary literature. We found no significant differences in postoperative ischemic or hemorrhagic complications by clopidogrel response phenotype, although complication rates in the overall study cohort were low. CR may be a spectrum from responder to partial responder to complete non-responder, and this may account for the differences in our CR cohort compared to the ROADSTER 2 protocol deviation cohort. Further investigation is warranted to determine if a quantitative assessment of CR is sufficient to identify patients at risk of developing secondary cerebrovascular ischemic events in this patient population.

Verifynow P2Y12 PRU-Guided Modification of Clopidogrel for Prevention of Recurrent Ischemic Stroke: A Real-World Prospective Cohort Study

INTRODUCTION

Clopidogrel resistance causes recurrent stroke. However, outcomes of modified antiplatelet medications to prevent recurrent ischemic stroke are not well known.

METHODS

Patients who received clopidogrel with and without modification as initial treatment for stroke were recruited and compared. The primary outcome was ischemic stroke and myocardial infarction at the 1-year follow-up. The secondary outcome was bleeding complications.

RESULTS

Overall, 206 patients treated with clopidogrel were enrolled and were divided into the modification (n = 39) and no modification (n = 167) groups. There was a significant difference in the incidence of severe cerebral arterial stenosis between the two groups (modification group, 16/39, 41.03%; no modification group, 36/167, 21.56%, P = 0.012) at baseline. The loss to follow-up rate was 12.14% (25/206). After adjustment for severe cerebral artery stenosis, antiplatelet modification based on the platelet reactivity unit (PRU) value significantly improved in the per protocol set (odds ratio 0.142, 95% confidential interval 0.022-0.898, P = 0.038). The area under the curve of the different PRU cutoff values were 0.630, 0.605, and 0.591 (P = 0.016, 0.051, and 0.092) for PRU 190, 208, and 235, respectively.

CONCLUSION

Verifynow P2Y₁₂ PRU-guided modification of clopidogrel for ischemic stroke significantly improved or prevented recurrence at the 1-year follow-up. Our findings suggest that clopidogrel therapy based on the PRU cutoff value of 190 should be considered to improve outcomes.

TRIAL REGISTRATION

ClinicalTrials.gov NCT02618265 (December 1, 2015).