Risk of stroke from new carotid artery occlusion in the Asymptomatic Carotid Surgery Trial-1.

BACKGROUND AND PURPOSE: In the Asymptomatic Carotid Surgery Trial-1 (ACST-1), 3120 patients with tight asymptomatic carotid stenosis were randomly assigned to medical treatment alone or to carotid endarterectomy and appropriate medication. Successful carotid endarterectomy significantly reduced 10-year stroke risk in younger patients. This study was undertaken to determine the risk of new occlusion and stroke during trial follow-up. METHODS: Patients with contralateral occlusion at trial entry (n=276) or incomplete duplex follow-up (n=137) were excluded. Risk of occlusion and stroke in patients with occlusion was estimated by Kaplan-Meier analysis. Cox proportional hazard regression models were used to determine risk factors for developing new occlusion and stroke. RESULTS: Median follow-up in 2707 patients was 80.0 months (interquartile range, 52.0-115.0). New occlusions occurred in 197 patients (1.1% per annum) but were more likely to occur in arteries with tight stenosis and in unoperated patients. Overall risk of stroke was 7.6% (95% confidence interval [CI], 6.6-8.7) and 15.5% (95% CI, 13.6-17.4) at 5 and 10 years, respectively; for patients with new occlusion, this significantly increased to 17.0% (95% CI, 11.6-22.4) and 20.8% (95% CI, 14.1-26.2), respectively (P<0.001). Stroke was significantly more likely to occur in patients developing occlusion (hazard ratio, 1.78; 95% CI, 1.26-2.51) irrespective of allocated treatment. CONCLUSIONS: New occlusions were uncommon after carotid endarterectomy in ACST-1. During long-term follow-up, occlusion and stroke were commoner among patients with ≥ 70% stenosis, most of whom had not undergone carotid endarterectomy. Occlusion was an independent prognostic risk factor for occurrence of stroke.

Quantification of Lipid-Rich Core in Carotid Atherosclerosis Using Magnetic Resonance T2 Mapping: Relation to Clinical Presentation.

OBJECTIVES: The aim of this study was to: 1) provide tissue validation of quantitative T2 mapping to measure plaque lipid content; and 2) investigate whether this technique could discern differences in plaque characteristics between symptom-related and non-symptom-related carotid plaques. BACKGROUND: Noninvasive plaque lipid quantification is appealing both for stratification in treatment selection and as a possible predictor of future plaque rupture. However, current cardiovascular magnetic resonance (CMR) methods are insensitive, require a coalesced mass of lipid core, and rely on multicontrast acquisition with contrast media and extensive post-processing. METHODS: Patients scheduled for carotid endarterectomy were recruited for 3-T carotid CMR before surgery. Lipid area was derived from segmented T2 maps and compared directly to plaque lipid defined by histology. RESULTS: Lipid area (%) on T2 mapping and histology showed excellent correlation, both by individual slices (R = 0.85, p < 0.001) and plaque average (R = 0.83, p < 0.001). Lipid area (%) on T2 maps was significantly higher in symptomatic compared with asymptomatic plaques (31.5 ± 3.7% vs. 15.8 ± 3.1%; p = 0.005) despite similar degrees of carotid stenosis and only modest difference in plaque volume (128.0 ± 6.0 mm3 symptomatic vs. 105.6 ± 9.4 mm3 asymptomatic; p = 0.04). Receiver-operating characteristic analysis showed that T2 mapping has a good ability to discriminate between symptomatic and asymptomatic plaques with 67% sensitivity and 91% specificity (area under the curve: 0.79; p = 0.012). CONCLUSIONS: CMR T2 mapping distinguishes different plaque components and accurately quantifies plaque lipid content noninvasively. Compared with asymptomatic plaques, greater lipid content was found in symptomatic plaques despite similar degree of luminal stenosis and only modest difference in plaque volumes. This new technique may find a role in determining optimum treatment (e.g., providing an indication for intensive lipid lowering or by informing decisions of stents vs. surgery).

Informed consent in randomised controlled trials: development and preliminary evaluation of a measure of Participatory and Informed Consent (PIC).

BACKGROUND: Informed consent (IC) is an ethical and legal prerequisite for trial participation, yet current approaches evaluating participant understanding for IC during recruitment lack consistency. No validated measure has been identified that evaluates participant understanding for IC based on their contributions during consent interactions. This paper outlines the development and formative evaluation of the Participatory and Informed Consent (PIC) measure for application to recorded recruitment appointments. The PIC allows the evaluation of recruiter information provision and evidence of participant understanding. METHODS: Published guidelines for IC were reviewed to identify potential items for inclusion. Seventeen purposively sampled trial recruitment appointments from three diverse trials were reviewed to identify the presence of items relevant to IC. A developmental version of the measure (DevPICv1) was drafted and applied to six further recruitment appointments from three further diverse trials to evaluate feasibility, validity, stability and inter-rater reliability. Findings guided revision of the measure (DevPICv2) which was applied to six further recruitment appointments as above. RESULTS: DevPICv1 assessed recruiter information provision (detail and clarity assessed separately) and participant talk (detail and understanding assessed separately) over 20 parameters (or 23 parameters for three-arm trials). Initial application of the measure to six diverse recruitment appointments demonstrated promising stability and inter-rater reliability but a need to simplify the measure to shorten time for completion. The revised measure (DevPICv2) combined assessment of detail and clarity of recruiter information and detail and evidence of participant understanding into two single scales for application to 22 parameters or 25 parameters for three-arm trials. Application of DevPICv2 to six further diverse recruitment appointments showed considerable improvements in feasibility (e.g. time to complete) with good levels of stability (i.e. test-retest reliability) and inter-rater reliability maintained. CONCLUSIONS: The DevPICv2 provides a measure for application to trial recruitment appointments to evaluate quality of recruiter information provision and evidence of patient understanding and participation during IC discussions. Initial evaluation shows promising feasibility, validity, reliability and ability to discriminate across a range of recruiter practice and evidence of participant understanding. More validation work is needed in new clinical trials to evaluate and refine the measure further.

Waiting times for carotid endarterectomy in UK: observational study.

OBJECTIVES: To assess timeliness of carotid endarterectomy services in the United Kingdom. DESIGN: Observational study with follow-up to March 2008. SETTING: UK hospitals performing carotid endarterectomy. PARTICIPANTS: UK surgeons undertaking carotid endarterectomy from December 2005 to December 2007. MAIN OUTCOME MEASURES: Provision and speed of delivery of appropriate assessments of patients; carotid endarterectomy and operative mortality; 30 day postoperative mortality. RESULTS: 240 (61% of those eligible) consultant surgeons took part from 102 (76%) hospitals and trusts. Of 9913 carotid endarterectomies recorded on hospital episode statistics, 5513 (56%) were included. Of the patients who underwent endarterectomy, 83% had a history of transient ischaemic attack or stroke. Of these recently symptomatic patients, 20% had their operation within two weeks of onset of symptoms and 30% waited more than 12 weeks. Operative mortality was 0.5% during the inpatient stay and 1.0% (95% confidence interval 0.7% to 1.3%) by 30 days. CONCLUSION: Only 20% of symptomatic patients had surgery within the two week target time set by the National Institute for Health and Clinical Excellence (NICE). Although operative mortality rates are comparable with those in other countries, some patients might experience disabling or fatal stroke while waiting for surgery and hence not be included in operative statistics. Major improvements in services are necessary to enable early surgery in appropriate patients in order to prevent strokes.