Efficacy of Dual Antiplatelet Therapy in Cerebrovascular Disease as Demonstrated by a Decline in Microembolic Signals

Aspirin plus clopidogrel versus aspirin mono-therapy for ischemic stroke: a meta-analysis

Objectives. Stroke is a common condition after a transient ischemic attack (TIA) or minor ischemic stroke (IS). Adding clopidogrel to aspirin may yield more beneficial outcomes than aspirin mono-therapy; meanwhile, the risk of bleeding in the acute phase remains poorly understood. Therefore, there is increasing emphasis on the risks and benefits of clopidogrel with aspirin compared with aspirin mono-therapy in an effort to treat TIA/IS. Design. We searched several electronic databases, including PubMed, Cochrane, and Embase, to identify eligible randomized controlled trials (RCTs) based on the index words comparing dual-antiplatelet therapy to aspirin mono-therapy for secondary stroke prevention updated to December, 2018. Results. A total of 11 RCTs met our inclusion criteria. The pooled analysis showed that clopidogrel plus aspirin was associated with a trend toward a reduction in recurrent IS (RR = 0.72, 95%CI = 0.65-0.81, p < .001), but not the recurrent stroke rate (RR = 0.81, 95% CI = 0.63-1.03, p = .09) than aspirin mono-therapy. There were differences in bleeding episodes (RR = 1.81, 95%CI = 1.65-1.99, p < .001), moderate-severe major bleeding (RR = 1.64, 95% CI = 1.24-2.16, p = .0005), or mild bleeding (RR = 2.25, 95%CI = 1.54-3.31, p < .001) between the study groups. Meanwhile, no benefit of reducing the risk of intracranial hemorrhage with dual-antiplatelet therapy was found in TIA/IS patients (RR = 1.44, 95% CI = 0.95-2.19, p = .09). Conclusions. The addition of clopidogrel to aspirin for patients with TIA or IS appeared to significantly reduce the risk of IS recurrence with a possible increase in the risk of bleeding compared with aspirin alone.

A comparative study of dual versus monoantiplatelet therapy in patients with acute large-artery atherosclerosis stroke

BACKGROUND

Antiplatelet drugs are recommended for patients with acute noncardioembolic stroke. However, few randomized clinical trials have investigated the safety and efficacy of dual antiplatelet therapy for these patients. The aim of this study was to evaluate the effects of treatment with clopidogrel and aspirin (combination therapy) and aspirin alone (monotherapy) on neurologic deterioration, platelet activation, and other short-term outcomes in patients with acute large-artery atherosclerosis stroke.

MATERIALS AND METHODS

Altogether 574 patients with acute (≤2 days) large-artery atherosclerosis stroke were randomly assigned to receive either combined clopidogrel and aspirin or aspirin alone. Platelet aggregation and platelet-leukocyte aggregation studies were performed at days 1 and 30. Primary outcomes including recurrent ischemic stroke, neurologic deterioration, periphery vascular events, and myocardial infarction were monitored. Safety endpoints were hemorrhagic episodes and death.

RESULTS

The prevalence of neurologic deterioration and recurrent ischemic stroke were lower in patients in the combination therapy group than in those of the monotherapy group (3.52% versus 9.78% and 1.76% versus 6.29%, respectively). At day 30 of treatment, the platelet aggregations and platelet-leukocyte aggregates were lower in patients who were treated with clopidogrel and aspirin than in patients given aspirin alone (P < .001).

CONCLUSIONS

For patients with acute large-artery atherosclerosis stroke, treatment with clopidogrel and aspirin for 1 month provided significantly greater inhibition of platelet activity than aspirin alone. Thus, dual therapy can be safer and more effective in reducing ischemic stroke recurrence and neurologic deterioration.

Recovery of normal hemodynamic activities after long-term medication in a patient with left internal carotid arterial occlusion

BACKGROUND AND OBJECTIVE

Aspirin, clopidogrel, cilostazol, and statins are thought to reduce the risk of cerebral infarction in patients with intracranial arterial stenosis. We present a case of multiple intracranial arterial stenoses in which increased cerebral blood flow (CBF) was demonstrated after long-term medical therapy.

CASE PRESENTATION

A 68-year-old man with a history of cerebral infarction showed complete occlusion of the left internal carotid artery with severe stenoses in the A1 segment of the left anterior cerebral artery (ACA) and the left posterior communicating artery resulting in poor visualization of the left middle cerebral artery (MCA) on magnetic resonance angiography (MRA). Administration of aspirin and clopidogrel prevented ischemia from recurring for 1 year; however, the stenoses never improved. Technetium-99m-L, L-ethylcysteinate dimer single-photon emission computed tomography (SPECT) demonstrated a significant decrease in CBF in the territory of the left MCA. Anastomosis between the superficial temporal artery and the MCA was recommended to the patient because no supplementary blood supply was expected through either the left A1 or posterior communicating artery. However, the patient refused surgery because of the associated risks. To enhance vasodilation, clopidogrel was replaced by cilostazol. One year later, the stenoses had partially improved. Further treatment with aspirin, cilostazol, simvastatin, and nateglinide contributed to the significant increase in CBF with normal hemodynamics, as shown with acetazolamide-loading SPECT.

CONCLUSION

The goal of treatment for intracranial arterial stenosis is to supply sufficient blood flow to the brain rather than to completely dilate the stenotic artery. Long-term treatment with aspirin, cilostazol, simvastatin, and nateglinide might help increase CBF in some patients with intracranial arterial stenosis.

Correlation between frequency of microembolic signals and efficacy of antiplatelet therapy in symptomatic carotid disease

BACKGROUND AND PURPOSE

The detection of microembolic signals in transcranial-Doppler monitoring is associated with a higher stroke risk. We investigated the correlation between the frequency of microembolic signals and the efficacy of the antiplatelet therapy in patients with a recent symptomatic carotid-artery stenosis.

SUBJECTS AND METHODS

Thirty-two patients (mean age: 70 years, 22 men) with a recent symptomatic carotid-artery stenosis underwent 30-minute TCD-monitoring. Twenty-three patients received acetylsalicylic-acid and 9 patients clopidogrel as antiplatelet-therapy. At the same day, the antiplatelet effect was measured with multiple-electrode-impedance aggregometry.

RESULTS

In 20 cases, the qualifying event was a stroke and in 12 cases, a TIA. Twenty-six of the patients had a >50% degree of stenosis. More than one microembolic signals were detected in 13 (40.6%) of the subjects, while multiple-electrode-impedance aggregometry revealed eight low responders (6 acetylsalicylic-acid, 2 clopidogrel). More than one microembolic signals were detected in 6 of the 8 (75.0%) patients with low response, but in only 7 of the 24 subjects (29.2%) with an effective antiplatelet treatment (sensitivity 75%, specificity 70.8%; Fisher's exact test: P = .038).

CONCLUSIONS

Our study suggests that in patients with recent symptomatic carotid-artery stenosis the detection of more than one microembolic signals might serve as a useful marker for the effectiveness of the antiplatelet treatment.

Clopidogrel plus aspirin versus aspirin alone for reducing embolisation in patients with acute symptomatic cerebral or carotid artery stenosis (CLAIR study): a randomised, open-label, blinded-endpoint trial

BACKGROUND

Few randomised clinical trials have investigated the use of antithrombotic drugs for early secondary prevention of stroke or transient ischaemic attack in patients with intracranial atherosclerotic stenosis. Microembolic signals, detected by transcranial doppler, are a surrogate marker of future stroke risk and have been used to show treatment efficacy in patients with extracranial carotid stenosis. We aimed to investigate whether treatment with clopidogrel plus aspirin reduced the number of microembolic signals detected with transcranial doppler ultrasound compared with aspirin alone in patients with recent stroke.

METHODS

The clopidogrel plus aspirin for infarction reduction in acute stroke or transient ischaemic attack patients with large artery stenosis and microembolic signals (CLAIR) trial was a randomised, open-label, blinded-endpoint trial. Between Oct 28, 2003, and Nov 19, 2008, patients with acute ischaemic stroke or transient ischaemic attack who had symptomatic large artery stenosis in the cerebral or carotid arteries and in whom microembolic signals were present on transcranial doppler were randomly assigned within 7 days of symptom onset to receive clopidogrel (300 mg for the first day, then 75 mg daily) plus aspirin (75-160 mg daily) or aspirin alone (75-160 mg daily) for 7 days. Patients were randomly assigned in blocks of four or six by use of a randomisation website. Monitoring of microembolic signals on transcranial doppler was done on days 2 and 7. The primary endpoint was the proportion of patients who had microembolic signals on day 2. Analysis was by modified intention to treat. All analyses were done by an investigator masked to both patient identity and the day the recording was taken. This trial is registered with the Centre for Clinical Trials, Chinese University of Hong Kong, number CUHK_CCT00164.

FINDINGS

100 patients were randomly assigned to clopidogrel plus aspirin (n=47) or aspirin monotherapy (n=53). 93 of 100 patients had symptomatic intracranial stenosis in either the intracranial internal carotid artery or the middle cerebral artery: 45 of 46 in the dual therapy group and 48 of 52 in the monotherapy group. At day 2, 14 of 45 patients in the dual therapy group and 27 of 50 patients in the monotherapy group for whom data were available had at least one microembolic signal on transcranial doppler (relative risk reduction 42.4%, 95% CI 4.6-65.2; p=0.025). Adverse events were similar in the two groups. No patients had intracranial or severe systemic haemorrhage, but two patients in the dual therapy group had minor haemorrhages.

INTERPRETATION

Combination therapy with clopidogrel and aspirin is more effective than aspirin alone in reducing microembolic signals in patients with predominantly intracranial symptomatic stenosis. Clinical trials are now warranted to investigate whether this combination treatment also results in a reduction in stroke incidence.

[Intracranial atherosclerosis]

Until recently, intracranial atheromatosis was a probably underdiagnosed clinicopathological entity that was rarely studied in depth. In the last years the advance and expansion in the use of non-invasive diagnostic tools have led intracranial atheromatosis to the front page among the most prevalent causes of stroke worldwide. Important efforts have been accomplished with the aim of identifying markers of poor outcome, which, besides the underlying mechanisms of cerebral ischemia in these patients, are the most important factors on which clinical and therapeutic decisions should be based. To date, the therapeutic armamentarium is scarce and far from optimun, regarding medical and endovascular measures. In this review we address the most important aspects of the natural history and cure treatment of intracranial atheromatosis.

Embolic Doppler ultrasound signal detection using continuous wavelet transform to detect multiple vascular emboli

BACKGROUND

Ischemic stroke is mainly caused by embolism. Vascular emboli can be solid or gaseous and can be non-invasively registered by transcranial Doppler ultrasound as microembolic signals (MESs). The existing methods are limited as they do not distinguish between cases in which a single embolus is present and those in which multiple emboli -- perhaps a mix of those gaseous and solid in nature -- are present. In a previous in vitro study, we have developed a wavelet-based algorithm to detect multiple emboli. We proceed with this technique to investigate whether it could prove useful in patients.

METHOD

MESs were collected during emboli monitoring from patients undergoing carotid artery stenting and from patients having middle cerebral artery stenosis, and continuous wavelet transform was used to detect multiple emboli.

RESULTS

From 17 MESs recorded from middle cerebral artery stenosis patients, we found no multiple MES. From 306 MESs recorded from carotid stenting, we found 31 multiple MESs.

CONCLUSION

Multiple emboli were detected and quantified in patients using continuous wavelet transform. These were difficult to observe using conventional analysis techniques.

Mild cognitive impairment in general practice: age-specific prevalence and correlate results from the German study on ageing, cognition and dementia in primary care patients (AgeCoDe)

BACKGROUND

Although mild cognitive impairment (MCI) represents a high-risk factor for developing dementia, little is known about the prevalence of MCI among patients of general practitioners (GPs).

AIMS

Estimation of age-specific prevalence for original and modified concepts of MCI and their association with sociodemographic, medical and genetic (apoE epsilon4 genotype) factors among patients of GPs.

METHODS

A GP practice sample of 3,327 individuals aged 75+ was assessed by structured clinical interviews.

RESULTS

Prevalence was 15.4% (95% CI = 14.1-16.6) for original and 25.2% (95% CI = 23.7-26.7) for modified MCI. Rates increased significantly with older age. Positive associations were found for apoE epsilon4 allele, vascular diseases and depressive symptoms.

CONCLUSION

MCI is frequent in elderly patients of GPs. GPs have a key position in secondary prevention and care of incipient cognitive deterioration up to the diagnosis of dementia.

Gaseous emboli detection based on a dual-wavelet transform analysis

Emboli monitoring is nowadays based on the assessment of microembolic signals by Doppler ultrasound. However, the present systems have problems in detecting multiple emboli. A more dedicated algorithm for post-processing of the recorded Doppler signals was proposed. Based on the hypothesis that single and multiple gaseous emboli can be quantified by combining discrete and continuous wavelet transformation, the aim of this study was to detect gaseous emboli and to validate our method visually. A flow rig was used where gaseous emboli were generated. Doppler signals and visual validation data of gaseous emboli were acquired simultaneously. Microembolic signals were extracted and analysed using wavelet transformation. Results were validated against a visual reference. At various degrees of bubble generation, the system had 100 per cent detection during a low frequency of bubble generation but an estimation error of 7.4 per cent during a high frequency of bubble generation. The estimation error varied between - 7.4 and +3 per cent. The system had a higher rate of success in detecting large gaseous emboli in small numbers than small gaseous emboli in large numbers. Single and double emboli were successfully detected and separated, whereas gaseous emboli clouds could be detected but not quantified. Being able to separate simultaneous gaseous emboli may offer new means of increasing detectability for embolism monitoring.