Effect of perioperative platelet inhibition on postcarotid endarterectomy mural thrombus formation. Results of a prospective randomized controlled trial using aspirin and dipyridamole in humans

Cervical Hematoma Following Carotid Endarterectomy is Morbid and Preventable

Objective:

Cervical hematoma (CH) following carotid endarterectomy (CEA) is a serious complication. We reviewed 12 years of CEA for CH requiring operative evacuation to determine its impact on the patient outcome and relationship to perioperative pharmacotherapy.

Methods:

A total of 2643 CEAs were reviewed. In all, 57 CHs requiring operative evacuation were compared to all the patients for general characteristics and with a case-controlled cohort group for pharmacologic details.

Results:

The occurrence of CH was stable from 1994 to 1998 and then increased from 1999 to 2003. The CH increased operative mortality, neurologic complications, adverse cardiac events, and cranial nerve injury. Combined platelet inhibition and dextran alone increased the risk of CH. The CH rate dropped by 65% after the observations were reported to the vascular surgeons.

Conclusion:

The CH following CEA requiring operative evacuation is associated with increased postoperative mortality and cardiac and neurologic morbidity. Combined platelet inhibition, use of dextran, and elevated creatinine are causally related to CH. Physician awareness and modified pharmacotherapy have decreased the problem.

Antithrombotic Therapy in Peripheral Arterial Occlusive Disease

This chapter about antithrombotic therapy for peripheral arterial occlusive disease is part of the seventh ACCP Conference on Antithrombotic and Thrombolytic Therapy: Evidence Based Guidelines. Grade 1 recommendations are strong and indicate that the benefits do, or do not, outweigh risks, burden, and costs, and Grade 2 suggests that individual patients' values may lead to different choices (for a full understanding of the grading see Guyatt et al, CHEST 2004;126:179S-187S). Among the key recommendations in this chapter are the following: For patients with chronic limb ischemia, we recommend lifelong aspirin therapy in comparison to no antiplatelet therapy in patients with clinically manifest coronary or cerebrovascular disease (Grade 1A) and in those without clinically manifest coronary or cerebrovascular disease (Grade 1C+). We recommend clopidogrel over no antiplatelet therapy (Grade 1C+) but suggest that aspirin be used instead of clopidogrel (Grade 2A). For patients with disabling intermittent claudication who do not respond to conservative measures and who are not candidates for surgical or catheter-based intervention, we suggest cilostazol (Grade 2A). We suggest that clinicians not use cilostazol in patients with less-disabling claudication (Grade 2A). In these patients, we recommend against the use of pentoxifylline (Grade 1B). We suggest clinicians not use prostaglandins (Grade 2B). In patients with intermittent claudication, we recommend against the use of anticoagulants (Grade 1A). In patients with acute arterial emboli or thrombosis, we recommend treatment with immediate systemic anticoagulation with unfractionated heparin (UFH) [Grade 1C]. We also recommend systemic anticoagulation with UFH followed by long-term vitamin K antagonist (VKA) in patients with embolism [Grade 1C]). For patients undergoing major vascular reconstructive procedures, we recommend UFH at the time of application of vascular cross-clamps (Grade 1A). In patients undergoing prosthetic infrainguinal bypass, we recommend aspirin (Grade 1A). In patients undergoing infrainguinal femoropopliteal or distal vein bypass, we suggest that clinicians do not routinely use a VKA (Grade 2A). For routine patients undergoing infrainguinal bypass without special risk factors for occlusion, we recommend against VKA plus aspirin (Grade 1A). For those at high risk of bypass occlusion and limb loss, we suggest VKA plus aspirin (Grade 2B). In patients undergoing carotid endarterectomy, we recommend aspirin preoperatively and continued indefinitely (Grade 1A). In nonoperative patients with asymptomatic or recurrent carotid stenosis, we recommend lifelong aspirin (Grade 1C+). For all patients undergoing extremity balloon angioplasty, we recommend long-term aspirin (Grade 1C+).

Antiplatelet therapy in aneurysmal subarachnoid hemorrhage: a systematic review

BACKGROUND AND PURPOSE

Observational studies suggest that platelet inhibitors reduce the risk of delayed cerebral ischemia (DCI) after aneurysmal subarachnoid hemorrhage and thereby have a beneficial effect on clinical outcome. Robust evidence, however, is lacking. We performed a systematic meta-analysis to determine whether antiplatelet therapy has a beneficial effect after SAH.

METHODS

We searched Medline and the Cochrane Library to identify all randomized controlled trials of antiplatelet drugs versus control and calculated relative risks with corresponding 95% confidence intervals (CIs) for poor outcome (dependence or death), the occurrence of DCI, and the occurrence of any intracranial hemorrhage.

RESULTS

We included 5 trials totaling 699 patients. The overall relative risk for poor outcome was 0.87 (95% CI, 0.65 to 1.17); for the occurrence of DCI (reported in 3 of the 5 studies), 0.65 (95% CI, 0.47 to 0.89); and for the occurrence of intracranial hemorrhage, 1.19 (reported in 4 of the 5 studies) (95% CI, 0.76 to 1.85).

CONCLUSIONS

Our data indicate that antiplatelet drugs reduce the risk of DCI in patients with subarachnoid hemorrhage. A randomized clinical trial is warranted to assess the effect on overall outcome.

Antiplatelet therapy for preventing stroke and other vascular events after carotid endarterectomy

BACKGROUND

Antiplatelet drugs are effective and safe in a wide variety of patients at high risk of vascular ischaemic events. Among patients undergoing vascular surgical procedures, these agents significantly reduce the risk of graft or native vessel occlusion. In this context we wished to examine their effects in patients after carotid endarterectomy (CEA).

OBJECTIVES

The objective of this review was to evaluate whether antiplatelet agents are safe and beneficial after endarterectomy of the internal carotid artery.

SEARCH STRATEGY

We searched the Cochrane Stroke Group Trials Register (last searched: 1 October 2002). In addition we performed comprehensive searches of the Cochrane Controlled Trials Register (Cochrane Library Issue 3, 2002), MEDLINE (January 1966 to September 2002) and EMBASE (January 1980 to September 2002), and checked all relevant papers for additional eligible studies.

SELECTION CRITERIA

We selected randomised, controlled, unconfounded trials comparing antiplatelet agents with control after carotid endarterectomy in symptomatic or asymptomatic carotid stenosis of different degrees. Treatment duration had to be at least 30 days after CEA. Follow-up should be at least three months.

DATA COLLECTION AND ANALYSIS

Two reviewers selected trials for inclusion, assessed trial quality, and extracted data independently from each other. From each trial we extracted, first the number of patients originally allocated to each treatment group, and, second the number of patients who met the criteria for each outcome (intention-to-treat analysis). We calculated a weighted estimate of the odds for each outcome event across studies using the Peto odds ratio method.

MAIN RESULTS

Six trials involving 907 patients were identified. For 'death (all causes)' the Peto odds ratio of 0.77 with a 95% confidence interval (CI) of 0.48-1.24 did not show a statistically significant difference between both treatment groups. For 'stroke (any)' the Peto odds ratio of 0.58 (95%CI: 0.34-0.98) indicated a statistically significant benefit in favour of antiplatelet drugs (p=0.04). Concerning the secondary outcome events 'vascular death', 'stroke or vascular death', 'serious vascular events', 'death or dependency', 'myocardial infarction', 'major extracranial haemorrhage', 'local haemorrhage requiring surgery', 'restenosis', 'TIA or amaurosis fugax', neither any benefit nor any hazard of antiplatelet drugs could be shown. For the outcome events 'intracranial haemorrhage', 'ischaemic stroke' and 'occurrence or progression of contralateral stenosis', data were either too sparse for meaningful analyses, or not available at all.

REVIEWER'S CONCLUSIONS

Our results may indicate that antiplatelet drugs did not significantly change the odds of 'death' but reduce the outcome 'stroke of any cause' in patients undergoing carotid endarterectomy. However, it can not be excluded that the beneficial effect in reducing stroke is due to chance. There is a suggestion that antiplatelets may increase the odds of haemorrhage, but there are currently too few data to quantify this effect.

Reoperation for acute hemispheric stroke after carotid endarterectomy: is there any value?

OBJECTIVE

Because the clinical benefit of urgent investigation and carotid re-repair for acute stroke complicating carotid endarterectomy (CEA) is uncertain, the results of this approach were examined in a large series of patients.

METHODS

In a consecutive series of 700 CEAs, 24 patients (3.4%) had a postoperative stroke. Thirteen of these 24 patients experienced major hemispheric deficits (hemiplegia with or without aphasia, forced eye deviation, and decreased consciousness) that prompted either immediate surgical reexploration or cerebral angiography with reoperation on the basis of angiogram results; these 13 patients are the subject of this report. Neurological improvement was attributed to carotid reopening when affected muscle strength increased to antigravity power within 6 hours of reoperation.

RESULTS

Of the 13 patients with severe postoperative deficits, 5 (38%) had the deficits when they awakened, 7 deficits occurred within 12 hours of surgery, and the only intracerebral hemorrhage in this series occurred 8 days after surgery. Five patients underwent urgent reoperation without angiography, and carotid occlusions were found and repaired in two patients. In another patient, the carotid was patent, and an intra-arterial injection of tissue plasminogen activator (20 mg) was given. In the seven patients who underwent cerebral angiography as the first step, two carotid occlusions and one residual stenosis with thrombus were found and repaired on an urgent basis. Surgical reopening of occluded arteries was followed by improvement in two of four patients, and early improvement was noted in one patient with a stenosis correction as well as in the patient who received intraoperative tissue plasminogen activator. Four patients who underwent urgent reoperation did not demonstrate a benefit soon after surgery. Two patients died, two were left with major deficits and five with moderate deficits, and four patients eventually had good recovery at a minimum of 6 months of follow-up.

CONCLUSION

In this series, approximately one-half of hemispheric strokes complicating CEA had an underlying correctable lesion (occlusion or stenosis), and these patients typically had delayed-onset strokes. Approximately one-half of these patients improved early as a result of reopening, although computed tomography revealed new infarcts in most of them. Urgent carotid repair may benefit a minority of selected patients who have a major stroke after CEA.

Antiplatelet agents, carotid endarterectomy, and perioperative complications

Neurosurgeons are frequently involved in choosing an antiplatelet therapy for their patients in the perioperative period. New data obtained from the Aspirin and Carotid Endarterectomy (ACE) Trial suggest that low-dose aspirin is superior to high-dose aspirin therapy in reducing rates of perioperative stroke and death. The ACE-related data are reviewed, and the authors provide an update on current Food and Drug Administration-approved antiplatelet therapies for secondary stroke prevention, as well as a summary of antiplatelet therapies being developed.

Collaborative overview of randomised trials of antiplatelet therapy--I: Prevention of death, myocardial infarction, and stroke by prolonged antiplatelet therapy in various categories of patients. Antiplatelet Trialists' Collaboration

OBJECTIVE

To determine the effects of "prolonged" antiplatelet therapy (that is, given for one month or more) on "vascular events" (non-fatal myocardial infarctions, non-fatal strokes, or vascular deaths) in various categories of patients.

DESIGN

Overviews of 145 randomised trials of "prolonged" antiplatelet therapy versus control and 29 randomised comparisons between such antiplatelet regimens.

SETTING

Randomised trials that could have been available by March 1990.

SUBJECTS

Trials of antiplatelet therapy versus control included about 70,000 "high risk" patients (that is, with some vascular disease or other condition implying an increased risk of occlusive vascular disease) and 30,000 "low risk" subjects from the general population. Direct comparisons of different antiplatelet regimens involved about 10,000 high risk patients.

RESULTS

In each of four main high risk categories of patients antiplatelet therapy was definitely protective. The percentages of patients suffering a vascular event among those allocated antiplatelet therapy versus appropriately adjusted control percentages (and mean scheduled treatment durations and net absolute benefits) were: (a) among about 20,000 patients with acute myocardial infarction, 10% antiplatelet therapy v 14% control (one month benefit about 40 vascular events avoided per 1000 patients treated (2P < 0.00001)); (b) among about 20,000 patients with a past history of myocardial infarction, 13% antiplatelet therapy v 17% control (two year benefit about 40/1000 (2P < 0.00001)); (c) among about 10,000 patients with a past history of stroke or transient ischaemic attack, 18% antiplatelet therapy v 22% control (three year benefit about 40/1000 (2P < 0.00001)); (d) among about 20,000 patients with some other relevant medical history (unstable angina, stable angina, vascular surgery, angioplasty, atrial fibrillation, valvular disease, peripheral vascular disease, etc), 9% v 14% in 4000 patients with unstable angina (six month benefit about 50/1000 (2P < 0.00001)) and 6% v 8% in 16,000 other high risk patients (one year benefit about 20/1000 (2P < 0.00001)). Reductions in vascular events were about one quarter in each of these four main categories and were separately statistically significant in middle age and old age, in men and women, in hypertensive and normotensive patients, and in diabetic and nondiabetic patients. Taking all high risk patients together showed reductions of about one third in non-fatal myocardial infarction, about one third in non-fatal stroke, and about one third in vascular death (each 2P < 0.00001). There was no evidence that non-vascular deaths were increased, so in each of the four main high risk categories overall mortality was significantly reduced. The most widely tested antiplatelet regimen was "medium dose" (75-325 mg/day) aspirin. Doses throughout this range seemed similarly effective (although in an acute emergency it might be prudent to use an initial dose of 160-325 mg rather than about 75 mg). There was no appreciable evidence that either a higher aspirin dose or any other antiplatelet regimen was more effective than medium dose aspirin in preventing vascular events. The optimal duration of treatment for patients with a past history of myocardial infarction, stroke, or transient ischaemic attack could not be determined directly because most trials lasted only one, two, or three years (average about two years). Nevertheless, there was significant (2P < 0.0001) further benefit between the end of year 1 and the end of year 3, suggesting that longer treatment might well be more effective. Among low risk recipients of "primary prevention" a significant reduction of one third in non-fatal myocardial infarction was, however, accompanied by a non-significant increase in stroke. Furthermore, the absolute reduction in vascular events was much smaller than for high risk patients despite a much longer treatment period (4.4% antiplatelet therapy v 4.8% control; five year