[Evaluation of treatment adaptation for low response to ASA in vascular surgery]. / Evaluation einer Therapieanpassung bei ASS-Low-Response in der Gefäßchirurgie.

BACKGROUND: A decreased antiplatelet prophylaxis (low response, LR/high on-treatment platelet reactivity, HPR) with acetylsalicylic acid (ASA) is associated with an increased risk of thromboembolic events. The prevalence of a LR is frequent with about 20% and a therapeutic regimen is not yet established. The aim of this prospective study was to evaluate the effectiveness of a therapeutic regimen for treatment adaptation when LR/HPR is detected in vascular surgery patients. METHODS: Overall, 36 patients under long-term antiplatelet treatment with 100 mg/day ASA and a detected ASA low response (ALR) were included in the study. In this patient group a modification of the prophylactic medication was carried out according to the established treatment plan and a control aggregometry was performed. The therapeutic regimen followed the test and treat principle. To evaluate the effect of ASA impedance, aggregometry with multiple electrodes was used (multiplate). RESULTS: All 36 patients were successfully transferred to response status with the treatment scheme. In 32 (88.89%) patients an increased dose of 300 mg/day ASA was carried out and in 2 (5.56%) patients the medication was changed from ASA to clopidogrel. A further 2 (5.56%) patients were switched to oral anticoagulation with phenprocoumon, due to other indications. Bleeding complications or other side effects did not occur. CONCLUSION: The chosen treatment regime for a low response proved to be effective and safe in vascular surgery patients. A guideline-compliant increase of the ASA dose from 100 mg to 300 mg/day predominantly led to an effective inhibition of platelet aggregation in the aggregometry.

[Prevalence of acetylsalicylic acid (ASA) - low response in vascular surgery]. / Prävalenz der ASS-Low-Response in der Gefäßchirurgie.

BACKGROUND: Research has revealed that a decreased antiplatelet effect (low response [LR]/high on-treatment platelet reactivity [HPR]) of acetylsalicylic acid (ASA) and clopidogrel is associated with an increased risk of thromboembolic events. There are extensive ASA low response (ALR) and clopidogrel low response (CLR) prevalence data in the literature, but there are only a few studies concerning vascular surgical patients. The aim of this study was to examine the prevalence and risk factors of ALR and CLR in vascular surgical patients. MATERIALS AND METHODS: We examined n = 154 patients with an antiplatelet long-term therapy, who were treated due to peripheral artery occlusive disease (PAD) and/or arteria carotis interna stenosis (CVD). To detect an ALR or CLR, we examined full blood probes with impedance aggregometry (ChronoLog® Aggregometer model 590). Risk factors were examined by acquisition of concomitant disease, severity of vascular disease, laboratory test results and medication. RESULTS: We found a prevalence of 19.3 % in the ALR group and of 21.1 % in the CLR group. Risk factors for ALR were an increased platelet and leucocyte count and co-medication with pantoprazole. We found no significant risk factors for a decreased antiplatelet effect of clopidogrel treatment. CONCLUSION: The investigated prevalence for ALR and CLR are in the range of other studies, particularly based on cardiological patients. More investigations are needed to gain a better evaluation of the risk factors for HPR and to develop an effective antiplatelet therapy regime to prevent cardiovascular complications.

Safety of early endarterectomy in patients with symptomatic carotid artery stenosis: an international multicenter study.

BACKGROUND AND PURPOSE: Although the latest recommendations suggest that carotid endarterectomy (CEA) should be performed in symptomatic carotid artery stenosis (sCAS) patients within 2 weeks of the index event, only a minority of patients undergo surgery within the recommended time-frame. The aim of this international multicenter study was to prospectively evaluate the safety of early CEA in patients with sCAS in everyday clinical practice settings. METHODS: Consecutive patients with non-disabling acute ischaemic stroke (AIS) or transient ischaemic attack (TIA) due to sCAS (≥ 70%) underwent early (≤ 14 days) CEA at five tertiary-care stroke centers during a 2-year period. Primary outcome events included stroke, myocardial infarction (MI) or death occurring during the 30-day follow-up period and were defined according to the International Carotid Stenting Study criteria. RESULTS: A total of 165 patients with sCAS [mean age 69 ± 10 years; 69% men; 70% AIS; 6% crescendo TIA; 8% with contralateral internal carotid artery (ICA) occlusion] underwent early CEA (median elapsed time from symptom onset 8 days). Urgent CEA (≤ 2 days) was performed in 20 cases (12%). The primary outcomes of stroke and MI were 4.8% [95% confidence interval (CI) 1.5%-8.1%] and 0.6% (95% CI 0%-1.8%). The combined outcome event of non-fatal stroke, non-fatal MI or death was 5.5% (95% CI 2.0%-9.0%). Crescendo TIA, contralateral ICA occlusion and urgent CEA were not associated (P > 0.2) with a higher 30-day stroke rate. CONCLUSIONS: Our findings indicate that the risk of early CEA in consecutive unselected patients with non-disabling AIS or TIA due to sCAS is acceptable when the procedure is performed within 2 weeks (or even within 2 days) from symptom onset.

[Switching from clopidogrel hydrogen sulfate to clopidogrel besylate. Impaired antiplatelet effect in patients with ischemic stroke]. / Umstellung von Clopidogrel-Hydrogensulfat auf Clopidogrel-Besilat. Unzureichende plättchenhemmende Wirkung bei Patienten mit Hirninfarkt.

The use of antiplatelet medications, such as acetylsalicylic acid (ASA), a combination of dipyridamol with ASA and also clopidogrel, is of great importance for the secondary prevention of ischemic stroke or transient ischemic attacks. In addition to the known form of clopidogrel hydrogen sulfate (CHS) a further clopidogrel salt, clopidogrel besylate (CB), has also been available since May 2008. The presented case illustrates that in patients with a history of cerebrovascular disease the antiplatelet response of CB can be diminished in comparison to CHS. Therefore we recommend testing the antiplatelet effectiveness when changing patient medication from CHS to CB.

Recanalization of acute symptomatic occlusions of the internal carotid artery.

BACKGROUND: Little is known about the natural course of internal carotid artery (ICA) occlusion and its possible recanalization. The present study was designed to evaluate recanalization rates of extracranial ICA occlusions in acute stroke patients by means of color-coded duplex sonography (CCDS). METHODS: 305 patients with acute ischemia in the territory of the middle cerebral artery were included in this study. All patients had a neurological examination on admission and on discharge and were rated by means of the European Stroke Scale (ESS). Extracranial color-coded duplexsonography, transcranial Doppler sonography and cranial computed tomography were immediately performed after admission and within 7 days. RESULTS: 254 patients showed no sign of hemodynamic relevant stenosis greater than 70% of the ICA. 21 patients had symptomatic high grade ICA stenosis. 20 patients had an acute occlusion and 10 patients an old ICA occlusion as judged by duplex sonographic criteria. Six patients (5 male, 1 female; age range 57 to 77 years) with an acute atherothrombotic or cardioembolic occlusion showed a recanalization of the ICA in the follow-up ultrasonography. Two patients with cardiogenic embolic occlusion of the ICA had the most favorable outcome and these patients showed no residual stenosis. 4 patients who had ultrasound findings consistent with atherosclerosis on follow-up examination (2 high-grade stenosis, 2 with carotid plaques) did not show a notable improvement of their ESS-score. Patients with carotid plaques developed complete MCA infarctions; the other 4 patients had partial anterior circulation infarction on follow-up CT. CONCLUSIONS: The present study showed that recanalization of the occluded ICA in acute stroke patients is more frequent than generally presumed. CCDS should be routinely performed in the follow-up of stroke patients as spontaneous recanalization may influence clinical outcome.

Distribution of artificially-produced microembolic signals into the cerebral circulation.

According to clinical observations, cardiogenic embolism occurs more often in the anterior than in the posterior cerebral circulation. An ultrasound (US) contrast agent was used to artificially produce microembolic signals (MES) to imitate the intracranial distribution of systemic emboli. Systemic microemboli were simulated by IV administered US agent (Levovist(R) 300 mg/mL as bolus). A total of 20 patients were monitored by means of transcranial Doppler sonography (TCD), 3 min after the injection, with a 2-MHz transducer simultaneously at 50 mm (middle cerebral artery, MCA, on one side) and 90 mm (basilar artery, BA). Four 3-min recordings were done (two of the right MCA, two of the left MCA, with the BA, respectively). Three observers and an automatic detection system independently performed an off-line analysis. A total of 160 recordings were analyzed. The mean numbers of detected high-intensity transient signals (HITS) were 34.5 +/- 28.2 in the right MCA (simultaneously registered HITS in the BA: 9.4 +/- 16.8) and 39.1 +/- 34.2 in the left MCA (simultaneously registered HITS in the BA: 12.2 +/- 14.5). Only 21.4 to 23.7% of all HITS were recorded in the BA. Microembolic signals artificially produced by means of US contrast agent made it possible to mimic the physiologic distribution of small embolic particles. In future, these might help to investigate the distribution of systemic emboli in different vascular territories in various pathologic conditions of the cerebral blood flow.

Acute brainstem symptoms associated with cervical syringomyelia.

Syringomyelia classically presents with slowly progressing dissociated sensory and upper and lower motor deficits. Atypical and acute manifestations have rarely been described. We report here on 3 patients with syringomyelia, who had acute and atypical brainstem symptoms with regard to the underlying disease. These symptoms occurred after acute elevation of the intrathoracic and intra-abdominal pressure, respectively, and remitted subsequently. Vertebrobasilar ischemia was initially suspected.