Temporal Variability of Platelet Reactivity in Patients Treated with Clopidogrel or Ticagrelor

Assessing the efficacy of VerifyNow platelet-function testing in predicting postoperative thromboembolic complications of neuroendovascular surgery: A systematic review and meta-analysis (part 1)

BACKGROUND

Despite the heavily debated use of routine platelet-function testing, the VerifyNow Platelet Reactivity Unit (PRU) assay has been increasingly adopted as standard of care for assessing risk of postoperative thromboembolic complications of neuroendovascular surgery.

OBJECTIVE

We conducted a systematic review and meta-analysis to examine the relationship between platelet response and risk of ischemic events from neuroendovascular surgery, assess the efficacy of point-of-care platelet-function testing in predicting thromboembolic outcomes, and assess whether a clinically useful threshold for platelet response can be defined in order to standardize guidelines.

METHODS

PubMed, Embase, and Scopus were searched. Following deduplication, articles were first screened for relevance by title and abstract, followed by full text.

RESULTS

Of 735 resultant articles, 22 studies consisting of 3266 patients undergoing neuroendovascular intervention were included. Diagnoses included both intracranial and extracranial pathologies, of which 45.8% were treated with flow diversion, 16.4% with stent-assisted coil embolization, 15.8% with intracranial stenting, 12.0% with simple coil embolization, 3.4% with balloon-assisted coil embolization, 3.6% with extracranial stenting, and 3.0% with an alternate method. 54.5% (12/22) of studies determined platelet hyporesponse to be an independent predictor of postoperative thromboembolic complications, with 27.3% (6/22) of studies reporting a similar, but non-statistically significant trend. 18.2% (4/22) of studies found no relationship between platelet response and postoperative thromboembolic complications. The estimated clinical threshold for PRU to prevent thromboembolic complications varied greatly across studies (Range: > 144-295 PRU). Meta-analysis found platelet hyporesponse to have a 2.23-fold increased risk of thromboembolic complications compared to normoresponders (RR = 2.23, P = 0.03).

CONCLUSION

While PRU demonstrates a significant predictive value for postoperative thromboembolic complications of neuroendovascular surgery, the target therapeutic threshold for minimizing ischemic events remains unclear. Further studies, such as large multicenter cohorts of the existing data, are needed to standardize guidelines.

A review of clopidogrel resistance in lower extremity arterial disease

Objective

Lower extremity arterial disease (LEAD) is a prevalent condition that produces a significant burden on health care systems. Patients with LEAD have an increased risk of major adverse cardiovascular events as well as major adverse limb events. Despite significant variation in guidance on antiplatelet therapy for LEAD worldwide, many governing bodies recommend clopidogrel as the preferred single anti-platelet agent. Clopidogrel is also used frequently in post-revascularization regimens, either as a single agent or as part of dual antiplatelet therapy. Clopidogrel is a thienopyridine prodrug that is metabolized in the liver by the CYP2C19 enzyme. Genetic variations in CYP2C19 are common and can influence an individual's ability to metabolize clopidogrel to its active metabolite.

Methods

This work completes a narrative review of the literature to consider whether CYP2C19 genetic testing should be routinely implemented in patients who are to be prescribed clopidogrel to improve outcomes in patients with LEAD.

Results

Recent advances in both cardiac and stroke medicine have demonstrated a role for patient genotyping to identify poor clopidogrel metabolizers and adopt alternative therapeutic strategies in these patient groups. This approach has been shown to improve clinical outcomes and has been incorporated into national and international guidance. Research studies suggest an association between CYP2C19 loss of function alleles and adverse outcomes in patients with LEAD taking clopidogrel.

Conclusions

The introduction of a precision medicine strategy in vascular surgery may have the potential to significantly improve clinical outcomes in this complex group of patients with multiple comorbidities.

Platelet Reactivity Was Not Associated with Infarct Size after Primary Percutaneous Coronary Intervention

Potent antiplatelet therapy after primary percutaneous coronary intervention (PCI) has the potential to reduce infarct size. This study analyzed the association between on-treatment platelet reactivity and myocardial infarct size in patients with ST-segment elevation myocardial infarction (STEMI) undergoing primary PCI. In this single-center, retrospective study, 253 patients who underwent primary PCI for STEMI were divided into two groups according to platelet reactivity measurements (53 patients in the high platelet reactivity [HPR] group and 200 in the non-HPR group). Technetium Tc-99m tetrofosmin single-photon emission computed tomography (SPECT) was performed before hospital discharge. We measured the infarct size using SPECT imaging and serial cardiac biomarker levels, and compared the infarct sizes of each group. The patients with HPR were older (65.5±13.2 vs. 60.6±12.1 years, p=0.011) than the patients with non-HPR. On the other hand, the non-HPR group had a higher incidence of smoking (26.4% vs. 51.0%, p=0.001) than the HPR group. Infarct size was similar between the two groups (22.6±17.3% vs. 24.8±17.7%, p=0.416). Multivariate analysis revealed that onset to balloon time >240 min (odds ratio [OR]=1.92; 95% confidence interval [CI]=1.08-3.40; p=0.025) and anterior infarction (OR=5.28; 95% CI=3.05-9.14; p<0.001) were independent predictors of large (>22%) infarct size. HPR was not a predictor of infarct size assessed by SPECT. The two groups also showed analogous cumulative creatinine kinase-myocardial band and troponin T levels. In conclusion, compared to non-HPR, HPR showed no significant association with myocardial infarct size measured by SPECT imaging in early phase of MI.

P2Y12 inhibitor monotherapy after coronary stenting according to type of P2Y12 inhibitor

OBJECTIVE

To compare P2Y12 inhibitor monotherapy after 3-month dual antiplatelet therapy (DAPT) with 12-month DAPT according to the type of P2Y12 inhibitor in patients undergoing percutaneous coronary intervention (PCI).

METHODS

The Smart Angioplasty Research Team: Comparison Between P2Y12 Antagonist Monotherapy vs Dual Antiplatelet Therapy in Patients Undergoing Implantation of Coronary Drug-Eluting Stents (SMART-CHOICE) randomised trial compared 3-month DAPT followed by P2Y12 inhibitor monotherapy with 12-month DAPT. In this trial, 2993 patients undergoing successful PCI with drug-eluting stent were enrolled in Korea. As a prespecified analysis, P2Y12 inhibitor monotherapy after 3-month DAPT versus 12-month DAPT were compared among patients receiving clopidogrel and those receiving potent P2Y12 inhibitor (ticagrelor or prasugrel), respectively. The primary endpoint was a composite of all-cause death, myocardial infarction or stroke at 12 months after the index procedure.

RESULTS

Among 2993 patients (mean age 64 years), 58.2% presented with acute coronary syndrome. Clopidogrel was prescribed in 2312 patients (77.2%) and a potent P2Y12 inhibitor in 681 (22.8%). There were no significant differences in the primary endpoint between the P2Y12 inhibitor monotherapy group and the DAPT group among patients receiving clopidogrel (3.0% vs 3.0%; HR: 1.02; 95% CI 0.64 to 1.65; p=0.93) as well as among patients receiving potent P2Y12 inhibitors (2.4% vs 0.7%; HR: 3.37; 95% CI 0.77 to 14.78; p=0.11; interaction p=0.1). Among patients receiving clopidogrel, P2Y12 inhibitor monotherapy compared with DAPT showed consistent treatment effects across various subgroups for the primary endpoint. Among patients receiving potent P2Y12 inhibitors, the rate of bleeding (Bleeding Academic Research Consortium types 2- 5) was significantly lower in the P2Y12 inhibitor monotherapy group than in the DAPT group (1.5% vs 5.0%; HR: 0.33; 95% CI 0.12 to 0.87; p=0.03).

CONCLUSIONS

Compared with 12-month DAPT, clopidogrel monotherapy after 3-month DAPT showed comparable cardiovascular outcomes in patients undergoing PCI.

TRIAL REGISTRATION NUMBER

NCT02079194.

Clinical significance of high on-treatment platelet reactivity in patients with prolonged clopidogrel therapy

BACKGROUND/AIMS

Prolonged dual antiplatelet therapy (DAPT) with aspirin and clopidogrel beyond 1 year has been shown to reduce ischemic events at the expense of increased bleeding. However, limited data are available on the clinical significance of platelet reactivity (PR) at 1 year.

METHODS

We retrospectively identified 331 patients who underwent percutaneous coronary intervention (PCI) and assessed the on-clopidogrel PR using VerifyNow P2Y12 assay at 1 year in a single center. Two hundred eleven patients were on DAPT for > 1 year. The relationship between high on-treatment platelet reactivity (HPR) at 1 year and clinical outcomes beyond 1 year, as well as the longitudinal change in PR was analyzed.

RESULTS

At 1 year, 135 (64%) patients showed HPR and 76 (36%) did not. There was a significant increase in ischemic endpoint events, including cardiovascular death, non-fatal myocardial infarction, and stroke/transient ischemic attack in patients with compared to without HPR at 1 year (hazard ratio [HR], 2.68; 95% confidence interval [CI], 1.06 to 6.77; p = 0.036). However, the incidence of any Bleeding Academic Research Consortium bleeding was significantly lower in the HPR group (HR, 0.11; 95% CI, 0.02 to 0.65; p = 0.015). In the longitudinal analysis, PR significantly decreased from post-load to 1 year after index PCI in the non-HPR group. Conversely, the HPR group showed high PR from baseline through 1 year.

CONCLUSION

HPR at 1 year may be a useful surrogate for predicting ischemic and bleeding events in patients on prolonged DAPT. Patients with and without HPR at 1 year showed different patterns of longitudinal change in PR.