Clopidogrel resistance is associated with thromboembolic complications in patients undergoing neurovascular stenting

BACKGROUND AND PURPOSE

Antiplatelet drug resistance has been associated with thromboembolic complications in patients after coronary stent placement. It has not been well-studied in patients who have neurovascular stent-placement procedures. This study aimed to analyze the relationship between antiplatelet drug resistance and neurovascular stent-placement complications.

MATERIALS AND METHODS

A prospective data base of all patients treated at our institution was used to identify patients with neurovascular stent-placement procedures. During a 4.5-year period, all patients undergoing neurovascular stent placement were evaluated for aspirin and clopidogrel resistance by using the VerifyNow assay. During an observational phase, all patients received 75 mg of clopidogrel and aspirin (group A). During the intervention phase (group B), patients were given additional clopidogrel on the basis of the clopidogrel resistance assay. We assessed the development of thromboembolic complications within 30 days of the procedure in patients who were resistant-versus-nonresistant to clopidogrel.

RESULTS

Of 96 patients who had neurovascular stent placement, 5.2% were resistant to aspirin and 36.5% were resistant to clopidogrel. Periprocedural thromboembolic complications were seen in 7 patients (7.3%). In a multivariate logistic regression model, clopidogrel resistance, higher diastolic blood pressure, and lack of statin use were significantly associated with periprocedural thromboembolic complication. There was a nonsignificant decrease in thromboembolic complications in patients whose clopidogrel dosage was tailored to the assay.

CONCLUSIONS

In our series, clopidogrel resistance was associated with increased periprocedural thromboembolic complications from neurovascular stent-placement procedures. Targeting the clopidogrel dose to platelet inhibition assays may improve clinical outcomes and requires further study.

Quantification of hoof deformation using optical motion capture

Deformation of the hoof capsule occurs during stance phase as a result of loading by the distal phalanx. The objective of this study was to evaluate optical motion capture as a technique for measuring hoof deformation during locomotion, and to quantify the deformation of the dorsal wall during stance phase. The front left feet of 3 clinically sound horses were used for this study. The hoof wall was cleaned and 9 retroreflective markers were glued to the lateral and dorsal hoof wall, and shoe. Each horse was trotted in a straight line at constant speed while marker positions during stance phase were recorded at 240 frames/s using a 3-dimensional (3-D) motion capture system. Similar patterns of hoof deformation were seen in all horses; the dorsal wall moved inwards towards the axis of the limb with displacement increasing proximally. Mean peak deformation varied between 0.17 and 0.92 mm in the dorsal hoof wall, and 0.18 and 0.76 mm in the lateral hoof wall. In all horses, movement of the shoe relative to the ground was < 0.7 mm throughout stance phase and movement of the hoof relative to the shoe was < 0.3 mm. Calibration using a micrometer indicated the motion capture system was accurate to < 0.1 mm in the configuration used for the study. This study showed that optical motion capture can be used to measure hoof deformation and successfully addresses some of the limitations of existing methods.