Antiplatelet Therapy in Stroke Prevention: Present and Future

Antiplatelet agents aspirin and dipyridamole, and the risk of different carcinoma in patients with type 2 diabetes mellitus: A Taiwan retrospective cohort study

Studies have shown aspirin decreases the risk of some cancers. However, the evidence reported the association between aspirin and cancer risk in the diabetic population. In this study, we investigate whether aspirin and dipyridamole decrease the risk of cancer in patients with type 2 diabetes. A total of 5308 patients with type 2 diabetes were identified by the National Health Insurance from 1998 to 2000 and followed up until 2013. The demographic characteristics among nondipyridamole nor aspirin, aspirin, and dipyridamole users were analyzed by using the χ(2) test. Cox proportional hazard regression models were used to determine the independent effects of no aspirin nor dipyridamole, aspirin, and dipyridamole users on the risk of different cancer. After adjustment with multiple covariates, both low and high doses of aspirin and dipyridamole decrease liver cancer with risk ratios of 0.56 (95% CI, 0.37-0.83), 0.14 (95% CI, 0.05-0.39), 0.61 (95% CI, 0.38-0.99), and 0.28 (95% CI, 0.12-0.66), respectively. Both low and high doses of aspirin decrease any types of cancer with risk ratios of 0.79 (95% CI, 0.64-0.98) and 0.49 (95% CI, 0.34-0.70), respectively. Therefore, we conclude aspirin may decrease any types of cancer and liver cancer, and dipyridamole may decrease the risk of liver cancer in patients with type 2 diabetes.

Histologic features of acute thrombi retrieved from stroke patients during mechanical reperfusion therapy

BACKGROUND

The histologic features of thrombus may differ according to the stroke subtypes. However, in acute reperfusion therapy, fibrin-specific thrombolytics are used based on the assumption that all thrombi are alike.

AIMS

The histologic characteristics of thrombi were compared between patients with different stroke etiologies.

METHODS

Between April 2010 and March 2012, we analyzed thrombi retrieved from acute stroke patients during mechanical thrombectomy. All thrombi were analyzed using component-specific stains such as Martius scarlet blue for fibrins and immunostaining with CD42b antibody for platelets. The stroke subtypes were determined based on the Trial of ORG 10172 in Acute Stroke Treatment classification.

RESULTS

Among 36 patients, 22 were diagnosed with cardioembolism, 8 with atherothrombosis, and 6 with undetermined etiology. In arteriogenic thrombi, red blood cells were most abundant (56.9 ± 12.2%), and the platelets covered the fibrin layers or were localized at the edge or periphery of the thrombus. In cardiogenic thrombi, fibrin was most abundant (39.5 ± 13.5%), and platelets were clustered within the rich fibrin. Red blood cells proportion was greater in arteriogenic thrombi than in cardiogenic thrombi (p < 0.001), whereas fibrin proportion was greater in cardiogenic thrombi than in arteriogenic thrombi (p = 0.003). Of six patients with undetermined etiology, the thrombi in five showed histologic features and composition similar to that of cardiogenic thrombi.

CONCLUSIONS

Acute thrombi showed different histologic features according to the stroke etiology. The distribution of platelets and proportion of red blood cells and fibrin were major distinguishing factors between stroke subtypes.

Predictive value of thrombus attenuation on thin-slice non-contrast CT for persistent occlusion after intravenous thrombolysis

BACKGROUND

In stroke erythrocyte-rich thrombi are more sensitive to intravenous thrombolysis with recombinant tissue plasminogen activator (IV-rtPA) and have higher density on non-contrast CT (NCCT). We investigated the relationship between thrombus density and recanalization and whether persistent occlusions can be predicted by Hounsfield unit (HU) measurements.

METHODS

In 88 IV-rtPA-treated patients with intracranial ICA or MCA occluding thrombus and follow-up imaging, thrombus and contralateral vessel attenuation measurements were performed on thin-slice NCCT. Mean absolute and relative HU were compared between patients with persistent occlusion (modified Thrombolysis in Cerebral Infarction system, grade 0/1/2a) and recanalization (grade 2b/3). Univariate and multivariate (adjusted for stroke subtype, clot burden score, occlusion site and time to thrombolysis) odds ratios for persistent occlusion were calculated. Additional prognostic value for persistent occlusion was estimated by adding HU measurements to the area under the curve (AUC) of known determinants and calculating optimal cut-off values.

RESULTS

Patients with persistent occlusion (n = 19) had significant lower mean HU (absolute 52.2 ± 9.5, relative 1.29 ± 0.20) compared to recanalization (absolute 63.1 ± 10.7, relative 1.54 ± 0.23, both p < 0.0001). Odds ratios for persistent occlusion were 3.1 (95% confidence interval, CI 1.6-6.0) univariate and 3.1 (95% CI 1.7-5.7) multivariate per 10 absolute HU decrease and 3.2 (95% CI 1.6-6.5) univariate and 4.1 (95% CI 1.8-9.1) multivariate per 0.20 relative HU decrease. Attenuation measurements significantly increased the AUC (0.67) of the known determinants to 0.84 (absolute HU) and 0.86 (relative HU). Cut-off values of <56.5 absolute HU and <1.38 relative HU showed optimal predictive values for persistent occlusion.

CONCLUSIONS

Thrombus density is related to recanalization rate. Lower absolute and relative HU are independently related to persistent occlusion and HU measurements significantly increase discriminative performances of known recanalization determinants.

Platelet membrane fluidity and Na+/K+ ATPase activity in acute stroke

Stroke is a consequence of a reduction in cerebral blood flow but the mechanisms involved in the production of ischemic damage are complex and probably not fully known. It is hypothesized that alterations in platelet membrane fluidity are directly related to the severity of the stroke as measured by the National Institute of Health Stroke Scale (NIHSS). Thus, the aim of the present study was to investigate Na+/K+ ATPase activity and platelet membrane fluidity, measured by fluorescent probes TMA-DPH and DPH in patients affected by ischemic stroke and controls in order to identify, if any, chemical-physical and/or functional modifications associated with cerebral ischemic damage. Patients were divided into three groups according to the presence of vascular risk factors (Diabetes Mellitus, Hypertension and Smoking) in order to evaluate the possible influence of each risk factor on the NIHSS score and both Na+/K+ ATPase activity and platelet membrane fluidity. Data showed a significant decrease in both Na+/K+ ATPase activity and platelet fluidity values in patients compared to controls. Moreover, all three groups showed a negative significant correlation between NIHSS and Na+/K+ ATPase activity and a positive significant correlation between NIHSS, TMA-DPH and DPH. In conclusion, the present data point out that alterations in the platelet membrane's chemical-physical (decreased fluidity) and functional properties (reduced Na+/K+ ATPase activity) rose proportionally with NIHSS increase. These modifications and their interaction with some vascular risk factors might be involved in the pathogenesis of ischemic damage development.

Contribuição na prevenção da isquemia cerebral pelo cilostazol, um inibidor da fosfodiesterase III: revisão de literatura

Esta revisão bibliográfica objetiva expor estas pesquisas sobre as ações do cilostazol no sistema nervoso central. O cilostazol é uma droga que demonstrou exercer inibição seletiva e potente da fosfodiesterase tipo III, ocasionando o aumento de adenosina cíclica -3',5'-monofosfato nas plaquetas, nas células endoteliais e nas células musculares lisas, sendo classificado como vasodilatador, antiagregante plaquetário e antitrombótico. É o fármaco de primeira escolha na claudicação intermitente devido à doença arterial obstrutiva periférica. Além disso, há evidências de que o cilostazol é eficaz no processo aterosclerótico cerebral, promovendo aumento do fluxo e volume sangüíneos e prevenindo infartos, especialmente lacunares e recorrentes, por diminuir a morte celular devido à apoptose e ao estresse oxidativo nas substâncias branca e parda.

Effect of Sarpogrelate, a 5-HT2A Antagonist, on Platelet Aggregation in Patients with Ischemic Stroke: Clinical-Pharmacological Dose-Response Study

BACKGROUND AND PURPOSE

It is widely accepted that antiplatelet therapy is effective for secondary prevention of atherosclerotic vascular diseases. We performed a double-blind, controlled clinical-pharmacological study to investigate the antiplatelet efficacy of sarpogrelate, a selective 5-hydroxytryptamine (5-HT(2A)) receptor antagonist, in patients with ischemic stroke, using a new assessment system employing combinations of 5-HT and epinephrine as agonists.

METHODS

Forty-seven patients with ischemic stroke were randomly assigned to three groups: 15 patients received 25 mg sarpogrelate (group L), 16 patients received 50 mg (group M), and 15 patients received 100 mg (group H) orally, three times daily for 7 days. The effect was expressed as maximum intensity of platelet aggregation on the last day of medication. Two combinations of agonists, 0.5 micromol/l 5-HT plus 3 micromol/l epinephrine, and 1 micromol/l 5-HT plus 3 micromol/l epinephrine, were used to induce platelet aggregation.

RESULTS

With both combinations of agonists, sarpogrelate treatment inhibited platelet aggregation dose-dependently (p < 0.025, Jonckheere test). In multiple-group comparison, the effect in group H was greater than that in group L or M (p < 0.025, Wilcoxon rank-sum test).

CONCLUSION

Sarpogrelate treatment inhibited platelet aggregation dose-dependently in patients with ischemic stroke, as judged by a new assessment system employing combinations of 5-HT and epinephrine as agonists.

Analysis of the lesion distributions and mechanism of acute middle cerebral artery infarctions involving the striatocapsular region

BACKGROUND AND PURPOSE

There is no clear description about the patterns of each mechanism of striatocapsular infarctions. The aims of our study were to elucidate differences in the distributions of lesions of acute middle cerebral artery (MCA) infarctions involving the striatocapsular region and to compare those following embolic striatocapsular infarctions with those originating from MCA disease.

METHODS

We prospectively enrolled patients with acute infarcts located in the lenticulostriate artery territory that were not lacunar infarcts. Brain coronal diffusion-weighted imaging (DWI) was obtained and magnetic resonance angiography (MRA) was carried out to evaluate the distribution of infarct lesions and MCA stenosis in all patients. The types of infarct distribution were divided into three categories: (1) dominant in the distal territory (DD), (2) distributed equally between the distal and proximal territories (DE), and (3) dominant in the proximal territory. We performed tests for embolic sources (transthoracic echocardiography, transesophageal echocardiography, Holter monitoring, and contrast-enhanced MRA including the aortic arch) in most patients. Stroke mechanisms were classified into stroke from proximal embolism, MCA disease, and stroke of undetermined etiology.

RESULTS

A total of 47 patients (28 men and 19 women; mean age, 62 years) were recruited. A proximal embolic source was significantly more prevalent in patients with a DE lesion than in those with a DD lesion. The most common proximal embolic source was of cardiac origin. In contrast, symptomatic MCA stenoses were more common in patients with a DD lesion than in those with a DE lesion.

CONCLUSIONS

These results suggest that the dominant area of striatocapsular infarction on coronal DWI is an important clue for stroke etiology. Coronal DWI could therefore be helpful to determining the mechanisms in patients with striatocapsular infarctions that are currently described as having an "undetermined etiology" according to the Trial of Org 10172 in Acute Stroke Treatment classification.