Clopidogrel Response Variability in Unruptured Intracranial Aneurysm Patients Treated with Stent-Assisted Endovascular Coil Embolization : Is Follow-Up Clopidogrel Response Test Necessary?

Thromboembolic complications during and after embolization of unruptured aneurysms: A chronological outcome in periprocedural thromboembolic events

Background

Ischemic complications develop after elective coil embolization procedures at a certain rate. The prevention of these events has been a longstanding issue for many interventional neuroradiologists. This study aimed to clarify whether procedural ischemic events after unruptured aneurysm embolization decrease over time with perioperative anti-thromboembolic treatment or surgical experience.

Methods

This study included patients with cerebral aneurysms in our institution between July 2012 and June 2020. Dual-antiplatelet therapy (DAPT) was performed (Phase 1). Thromboembolic events developed at a certain rate; thus, rivaroxaban was administered with single-antiplatelet therapy (SAPT) to improve thromboembolic results (Phase 2), showing better outcomes than in Phase 1. Subsequently, DAPT was administered again (Phase 3). Ischemic complications were evaluated in each phase or compared between the DAPT group and the direct oral anticoagulant (DOAC) with the clopidogrel (DOAC+SAPT) group.

Results

Relatively, fewer symptomatic ischemic events were noted in Phase 2 or the DOAC+SAPT group, but the outcome was not better in Phase 3 than in Phase 2. Symptomatic complications were more common in Phase 3 than in Phases 1 and 2.

Conclusion

Ischemic complications occurred at a certain rate after endovascular procedures for unruptured aneurysms. The incidence did not decrease over time; particularly, standard DAPT plus postoperative anti-thromboembolic medication did not adequately decrease complications in Phase 3 compared to Phases 1 and 2. Therefore, accumulated experience or a learning curve could not explain the results. DOAC administration might decrease the risk of these events, but further accumulation of evidence or prospective investigation is warranted.

Ticagrelor versus clopidogrel in stent-assisted coil embolization of unruptured intracranial aneurysms

BACKGROUND

Dual antiplatelet therapy is widely used for stent-assisted coil embolization (SACE) for unruptured intracranial aneurysms (UIAs) to prevent thromboembolic events (TEs). Compared to clopidogrel associated with aspirin, knowledge of the safety and efficacy of ticagrelor is lacking in large studies to date.

METHODS

A retrospective cohort study was conducted from January 2016 to December 2018 with at least one year of follow-up in a single institution and systemic review.

RESULTS

Altogether, 153 patients with UIA receiving SACE were separated into two groups: 113 patients receiving clopidogrel plus aspirin and 40 patients receiving ticagrelor plus aspirin. Acute in-stent thrombotic events were noted in two patients in the clopidogrel group (1.77%) and none in the ticagrelor group (0%). Additionally, one patient (0.88%) in the clopidogrel group had an early ischemic stroke (<3 months). Delayed ischemic stroke was noted in 6 patients (5.31%) in the clopidogrel group and 3 patients (7.50%) in the ticagrelor group. There were no major hemorrhagic events in either group. The two groups showed no significant differences with regard to ischemic stroke or hemorrhagic stroke.

CONCLUSION

Compared to the clopidogrel based regimen, ticagrelor can also reduce TEs without increasing bleeding tendency for SACE of UIAs. Ticagrelor combined with low-dose aspirin is a safe and effective alternative option for SACE.

Long-term complications after stent assist coiling dependent on clopidogrel response

BACKGROUND

Dual antiplatelet therapy (DAPT) is necessary for stent assisted coiling. However, long term use of DAPT has a potential risk of hemorrhagic events. We aimed to examine the relationship between clopidogrel reactivity and complications.

METHODS

Patients who underwent stent assisted coiling for unruptured aneurysms or previously treated aneurysms and received periprocedural DAPT in our institution between August 2011 to March 2020 were included. Platelet reactivity for clopidogrel was measured by VerifyNow assay system, and we defined the cut off value of P2Y12 Reaction Units (PRU) at 208 and classified patients as hypo-responders (PRU≧208) or responders (PRU<208). The rates of hemorrhagic and thrombotic events within 30 days (acute phase) and 30 days after the procedure (delayed phase) were compared between the two groups. Furthermore, changes in hemoglobin levels were measured before and after the procedure and at chronic stages (1 to 6 months thereafter).

RESULTS

From 61 patients included in this study, 36 patients were hypo-responders and 25 patients were responders. Hemorrhagic events occurred 8.0% only in responders in the acute phase (p = 0.16), and 2.78% in hypo-responders and 20.0% in responders in the delayed phase (p = 0.037). Changes in hemoglobin levels before and after the procedure were 1.22 g/dl in hypo-responders and 1.74 g/dl in responders (p = 0.032) while before the procedure and chronic stages they were 0.39 g/dl in hypo-responders and 1.39 g/dl in responders (p <  0.01). Thrombotic events were not significantly different between the two groups.

CONCLUSION

Long term use of DAPT after stent assisted coiling is related to hemorrhagic events in the delayed phase. Preventing for hemorrhagic events, the duration of DAPT should be carefully considered in clopidogrel responders.

Utility of platelet function testing in stent-assisted coiling of cerebral aneurysms

BACKGROUND

Thromboembolic complications are the primary risks of stent-coiling of cerebral aneurysms. The utility of platelet function testing in stent-assisted aneurysm coiling remains controversial. This study aimed to assess a pharmacy-mediated antiplatelet management protocol for stent-assisted coiling.

METHODS

Stent-coiled aneurysms at an academic institution in the United States between 2015 and 2018 were retrospectively reviewed. All patients were managed using a pharmacy-mediated antiplatelet protocol, which required repeated platelet function testing and subsequent dose adjustments. Medication dosage, number of adjustments, aspirin reaction units (ARU) and P2Y12 reaction units (PRU), as well as complication rates, angiographic and functional outcome were analyzed.

RESULTS

A total of 56 aneurysms (median size 5 mm, range 2.6-14.0 mm) in 54 patients (median age 58.5 years) were treated with stent-assisted coil embolization. Most aneurysms were located at the basilar tip (28.6%). Median pre-procedure ARU and PRU were 442.5 (range 363-594) and 123.5 (range 1-252), respectively. Approximately two-thirds of all procedures required at least one aspirin dose adjustment and 88.5% of procedures required at least one clopidogrel dose adjustment. There were two (3.6%) thromboembolic complications. One of the thromboembolic complications occurred in a patient where the pharmacy-mediated protocol was violated. There were no hemorrhagic complications. Last imaging follow-up demonstrated complete aneurysm occlusion in 83.9%.

CONCLUSION

In patients where the pharmacy-mediated antiplatelet protocol was followed, the thromboembolic complication rate was 1.8%. This complication rate compares favorably to those reported in large contemporary series. Nevertheless, the pharmacy-mediated protocol places a significant burden on both the patient and healthcare system.

The Efficacy of P2Y12 Reactive Unit to Predict the Periprocedural Thromboembolic and Hemorrhagic Complications According to Clopidogrel Responsiveness and Safety of Modification of Dual Antiplatelet Therapy : A Meta-Analysis

The efficacy of P2Y12 reaction unit (PRU) of VerifyNow still remains as a controversial issue in neurointervention. So we investigated the usefulness of PRU of VerifyNow to predict the peri-procedural thromboembolic events (TE) and hemorrhagic events (HE). And we evaluated the safety of modified dual antiplatelet therapy (DAPT) or triple antiplatelet therapy (TAPT) for clopidogrel hyporesponders. We searched MEDLINE, EMBASE, the Cochrane Central Register of Controlled Trials, Web of Science and Scopus on August 19 2018. Data was collected the 1) incidence of TE between clopidogrel responder and clopidogrel hypo-responder, 2) incidence of HE between clopidogrel hyper-responder and clopidogrel responder and hypo-responder, and 3) incidence of TE and HE between modified DAPT or TAPT and standard DAPT in clopidogrel hypo-responder. High cut-off value of PRU was defined as PRU >40% or <220. Fifteen studies were enrolled. Clopidogrel responder showed lower incidence of TE than hypo-responder (risk ratio [RR], 0.32; 95% confidence interval [CI], 0.17-0.61; p<0.001). With the high cut-off value of PRU, clopidogrel responder showed more lower incidence of TE than hypo-responder (RR, 0.11; 95% CI, 0.02-0.45; p=0.002). The incidence of periprocedural HE have higher on clopidogrel hyper-responder than clopidogrel responder and hypo-responder (RR, 4.26; 95% CI, 1.10-16.44; p=0.04; I2=66%). The incidence of periprocedural TE after changing regimen of DAPT for clopidogrel hypo-responder have a tendency to reduce, but there was no significant difference between modified DAPT or TAPT group and standard DAPT group (p>0.05). The incidence of periprocedural HE after changing regimen of DAPT for clopidogrel hypo-responder was no significant difference between modified DAPT or TAPT group and standard DAPT group (p>0.05). PRU is a useful tool as a predictor of peri-procedural TE or HE on neurointervention. PRU has a threshold effect of cut-off value to predict the peri-procedural TE. Modified DAPT or TAPT to prevent TE in clopidogrel hypo-responders could not reduce the incidence of TE. We should investigate the further research about modification of regiment on neurointervention.