Aspirin Resistance May Not Be Associated with Clinical Outcome after Acute Ischemic Stroke: Comparison with Three Different Platelet Function Assays / 대한뇌졸중학회지

BACKGROUND: Aspirin resistance (AR) in platelet function assays showed substantial variation depending on the methods used to evaluate it. METHODS: In this study, we prospectively compared the results of Multiplate impedance platelet aggregometry (IPA) with those of light transmission aggregometry (LTA) and VerifyNow(R) system in determination of the prevalence of aspirin resistance (AR) and investigated the correlation between its presence and poor outcome (modified Rankin scale >2) in 105 patients with aspirin after acute ischemic stroke (AIS). RESULTS: After 5 days of using aspirin, 15 patients (14.3%) were classified as aspirin-resistance with the use of IPA, 24 patients (22.9%) by the LTA, and 14 patients (13.3%) by VerifyNow. Good agreement between the results of IPA and VerifyNow, was found (R=0.674, P<0.01). The concordance rate of AR detection was high between VerifyNow and IPA (k=0.72, P<0.01), albeit quite low between LTA and IPA. Regarding on its influence on clinical outcome after AIS, there wasn't any significant relationship between occurrence of poor outcome and the presence of AR in three platelet function assays. CONCLUSION: This study reveals that the incidence of AR in AIS might be highly test-specific. IPA seems to be similar to VerifyNow as a platelet function test.

The Difference in Aspirin Resistance Based on an Optical Platelet Aggregometer and the PFA-100 in Patients with Acute Ischemic Stroke / 대한뇌졸중학회지

BACKGROUND: There are many causes for the failure of aspirin therapy in patients with acute ischemic stroke. Laboratory aspirin resistance (AR) might be involved in clinical aspirin non-response. The PFA-100 is a laboratory method to evaluate AR in the clinical setting. However, there has been limited data regarding concordance with optical platelet aggregometry, which is considered the gold standard for detecting AR. We retrospectively analyzed platelet function tests using the PFA-100 and an optical platelet aggregometer in 86 patients with acute ischemic stroke. METHODS: Eighty six patients were enrolled in the study and were evaluated the platelet function test by optical aggregometer and a PFA-100. We determined the variability in the prevalence of AR and the kappa value between the two tests in patients with acute ischemic stroke. RESULTS: Among 86 patients, 27 (31.4%) were detected as AR by the optical aggregometer and 31 (36.0%) by the PFA-100. There were 13 cases of AR (15.1%) in both laboratory methods. The optical platelet aggregometer results showed that female gender (P=0.03), aspirin monotherapy (P =0.05), and NIHSS at baseline (P=0.04) were related with AR in acute ischemic stroke. Multiple logistic regression analysis showed that NIHSS was independently associated with AR of the optical platelet aggregometer (OR=1.12 95%, CI: 1.00-1.25, P=0.05). CONCLUSION: The prevalence of AR was similar between the PFA-100 and the optical platelet aggregometer in patients with acute ischemic stroke. However, the concordance rate of these two tools is low.

Prehospital Notification from the Emergency Medical Service Reduces the Transfer and Intra-Hospital Processing Times for Acute Stroke Patients

BACKGROUND AND PURPOSE: There is little information available about the effects of Emergency Medical Service (EMS) hospital notification on transfer and intrahospital processing times in cases of acute ischemic stroke. METHODS: This study retrospectively investigated the real transfer and imaging processing times for cases of suspected acute stroke (AS) with EMS notification of a requirement for intravenous (IV) tissue-type plasminogen activator (t-PA) and for cases without notification. Also we compared the intra-hospital processing times for receiving t-PA between patients with and without EMS prehospital notification. RESULTS: Between December 2008 and August 2009, the EMS transported 102 patients with suspected AS to our stroke center. During the same period, 33 patients received IV t-PA without prehospital notification from the EMS. The mean real transfer time after the EMS call was 56.0+/-32.0 min. Patients with a transfer distance of more than 40 km could not be transported to our center within 60 min. Among the 102 patients, 55 were transferred via the EMS to our emergency room for IV t-PA. The positive predictive value for stroke (90.9% vs. 68.1%, p=0.005) was much higher and the real transfer time was much faster in patients with an EMS t-PA call (47.7+/-23.1 min, p=0.004) than in those without one (56.3+/-32.4 min). The door-to-imaging time (17.8+/-11.0 min vs. 26.9+/-11.5 min, p=0.01) and door-to-needle time (29.7+/-9.6 min vs. 42.1+/-18.1 min, p=0.01) were significantly shorter in the 18 patients for whom there was prehospital notification and who ultimately received t-PA than in those for whom there was no prehospital notification. CONCLUSIONS: Our results indicate that prehospital notification could enable the rapid dispatch of AS patients needing IV t-PA to a stroke centre. In addition, it could reduce intrahospital delays, particularly, imaging processing times.

A Case of Essential Thrombocytosis with Cerebral Infarction

Essential thrombocytosis (ET) is a clonal myeloproliferative disorder, characterized predominantly by a markedly elevated platelet count without known cause. We report a case of essential thrombocytosis, the only clinical manifestation of which consisted of neurologic symptoms, including headache, dysarthria, right hemiparesis with a relatively benign and slowly progressive clinical course. Neuroradiologic examination (Brain CT and MRI) disclosed a multiple infarction in the both basal ganglia and left parietal region. These findings are discussed in relation to the possible pathogenetic mechanisms of the vascular occlusion due to abnormal platelet function in ET.