Combined use of aspirin and heparin inhibits in vivo acute carotid thrombosis

Biochemical aspirin resistance is associated with increased stroke severity and infarct volumes in ischemic stroke patients

To explore the correlation of aspirin resistance (AR) with clinical stroke severity and infarct volume using diffusion-weighted imaging (DWI) in 224 Chinese ischemic stroke patients who were taking aspirin before stroke onset. In those patients, the median age was 64 years (IQR, 56-75 years), and males accounting for 54.9%(123)of the total subjects. Fifty of 224 enrolled patients (22.3%; 95% confidence interval (CI), 16.9% to 27.7%) showed AR. In the median regression model, significant increase was estimated in NIHSS score of 0.04 point for every 1-point increase in aspirin reaction units (ARU) (95% CI, 0.02 to 0.06; P<0.001). Diffusion-weighted MRI (DWI)-measured infarct volume were significantly higher in patients with AR as compared with those with AS [13.21 (interquartile ranges [IQR], 8.51-23.88) vs.4.26 (IQR, 1.74-11.62); P<0.001). Furthermore, a statistically significant increase was also measured in NIHSS score of 0.05 point for every 1-point increase in ARU in the median regression model (95% CI, 0.03 to 0.08; P<0.001). The median DWI infarct volume was significantly larger in the highest ARU quartile when compared to that in the low 3 quartiles (P<0.001). In conclusion, stroke patients with AR indicated higher risk of severe strokes and large infarcts compared to patients in the aspirin-sensitive group.

Aspirin resistance is associated with increased stroke severity and infarct volume

OBJECTIVES

To investigate whether aspirin resistance is associated with initial stroke severity and infarct volume, using diffusion-weighted imaging (DWI) in patients with acute ischemic stroke that occurred while taking aspirin.

METHODS

We studied a total of 310 patients who were admitted within 48 hours of acute ischemic stroke onset. All patients had been taking aspirin for at least 7 days before stroke onset. Aspirin resistance, defined as high residual platelet reactivity (HRPR) on aspirin treatment, was measured using the VerifyNow assay and defined as an aspirin reaction unit ≥550. Initial stroke severity was assessed using the NIH Stroke Scale (NIHSS) score. Infarct volume was measured using DWI.

RESULTS

HRPR occurred in 86 patients (27.7%). The initial NIHSS score (median [interquartile range]) was higher in patients with HRPR than in the non-HRPR group (6 [3-15] vs 3 [1-8], p < 0.001). DWI infarct volumes were also larger in the HRPR group compared to the non-HRPR group (5.4 [0.8-43.2] vs 1.7 [0.4-10.3], p = 0.002). A multivariable median regression analysis showed that HRPR was significantly associated with an increase of 2.1 points on the NIHSS (95% confidence interval 0.8-4.0, p < 0.001) and an increase of 2.3 cm(3) in DWI infarct volume (95% confidence interval 0.4-3.9, p < 0.001).

CONCLUSIONS

Aspirin resistance is associated with an increased risk of severe stroke and large infarct volume in patients taking aspirin before stroke onset.

Should heparin be reversed after carotid endarterectomy? A randomised prospective trial

OBJECTIVE

To investigate whether heparin reversal after carotid endarterectomy reduces the incidence of haemorrhagic complications.

DESIGN

A randomised prospective trial.

METHODS

Sixty-four patients randomised to reversal of heparin or no reversal, of whom 31 received protamine titrated to the residual circulating heparin at closure of arteriotomy. Measurements included serial activated clotting times (ACTs), wound drainage, neck swelling using duplex Doppler imaging to measure the depth from skin to carotid bifurcation, and the recording of all complications.

RESULTS

Wound drainage volumes were significantly reduced by protamine reversal (68.5 ml compared to 35 ml, p < 0.001), but neck swelling was not (72 mm compared to 70 mm, p = 0.77). Two patients who were not reversed developed neck haematomas requiring evacuation. More importantly, two patients receiving protamine, thrombosed the operated internal carotid artery (ICA) postoperatively and died despite urgent thrombectomy. A further patient who was not randomised in this study but who received protamine also developed ICA thrombosis within the same 3 month period.

CONCLUSIONS

Reversing heparin with protamine reduces postoperative wound drainage after carotid surgery but may predispose to ICA thrombosis and stroke. This is in keeping with a previous retrospective study published during our trial.