Edward Wong

ASPECT scoring to estimate >1/3 middle cerebral artery territory infarction.

PURPOSE To compare the inter-observer reliability of Alberta Stroke Programme Early CT Scoring (ASPECTS) with the ICE (Idealize-Close-Estimate) method of estimating > 1/3 middle cerebral artery territory (MCAT) infarction amongst stroke neurologists and to determine how well ASPECT Scoring predicts > 1/3 MCAT infarctions in acute ischemic stroke (AIS). BACKGROUND The European Cooperative Acute Stroke Study suggested that > 1/3 involvement of the MCAT on early CT scan was a risk factor for symptomatic intracerebral hemorrhage (SICH) following treatment with tissue plasminogen activator (tPA) for AIS but, in the absence of a systematic method of estimation had poor interobserver reliability (Kappa 0.49). The ICE method was developed to standardize the approach to estimating early MCAT infarct size and has very good interobserver reliability (Kappa 0.72). ASPECTS has comparable interobserver reliability and is reported to predict both neurological outcome and SICH. METHODS Five stroke neurologists were tested with 40 AIS CT scans. Each performed blinded independent assessments of early ischemic changes with both ASPECTS and ICE. The reference standard was majority opinion of 1/3 MCAT determination of five neuroradiologists. A receiver operator curve (ROC) was constructed and likelihood ratios (LR) were calculated. Chance corrected agreement (kappa) and chance independent agreement (phi) were calculated for both methods, and analysis of variance was used to calculate reliability by intraclass correlation coefficient (ICC) for ASPECTS. RESULTS The LR for a positive test (> 1/3 MCAT) were extremely large and conclusive (approaching infinity) for ASPECTS of 0-3; were large and conclusive (30, 20, and 10) for ASPECTS of 4, 5, and 6 respectively; was an unhelpful 1 for ASPECTS of 7, and were again extremely large and conclusive (approaching zero) for ASPECTS of 8-10. A ROC plot supported an ASPECTS cutoff of < 7 as best for 1/3 MCAT estimation (94% sensitivity and 98% specificity). Kappa and Phi statistics were moderately good for both ASPECTS and ICE (0.7). ICC for ASPECTS was 0.8. CONCLUSIONS When experienced stroke neurologists utilize a formalized method of quantifying early ischemic changes on CT, either ASPECTS or ICE, the interobserver agreement and reliability are satisfactory. ASPECTS allows for a strong and conclusive estimation of the presence of 1/3 MCAT involvement and a cutoff point of < 7 results in best test performance.

Improved outcomes in stroke thrombolysis with pre-specified imaging criteria.

BACKGROUND A 1995 National Institute of Neurological Disorders (NINDS) study found benefit for intravenous tissue plasminogen activator (tPA) in acute ischemic stroke (AIS). The symptomatic intracranial hemorrhage (SICH) rate in the NINDS study was 6.4%, which may be deterring some physicians from using this medication. METHODS Starting December 1, 1998, patients with AIS in London, Ontario were treated according to NINDS criteria with one major exception; those with approximately greater than one-third involvement of the idealized middle cerebral artery (MCA) territory on neuroimaging were excluded from treatment. The method used to estimate involvement of one-third MCA territory involvement bears the acronym ICE and had a median kappa value of 0.80 among five physicians. Outcomes were compared to the NINDS study. RESULTS Between December 1, 1998 and February 1, 2000, 30 patients were treated. Compared to the NINDS study, more London patients were treated after 90 minutes (p<0.00001) and tended to be older. No SICH was observed. Compared to the treated arm of the NINDS trial, fewer London patients were dead or severely disabled at three months (p=0.04). Compared to the placebo arm of the trial, more patients made a partial recovery at 24 hours (p=0.02), more had normal outcomes (p=0.03) and fewer were dead or severely disabled at three months (p=0.004). CONCLUSIONS The results of the NINDS study were closely replicated and, in some instances, improved upon in this small series of Canadian patients, despite older are and later treatment. These findings suggest that imaging exclusion criteria may optimize the benefits of tPA.

Incidence of Transient Ischemic Attack in Auckland, New Zealand, in 2011 to 2012

Background and Purpose— There have been few recent population-based studies reporting the incidence (first ever) and attack rates (incident and recurrent) of transient ischemic attack (TIA). Methods— The fourth Auckland Regional Community Stroke study (ARCOS IV) used multiple overlapping case ascertainment methods to identify all hospitalized and nonhospitalized cases of TIA that occurred in people ≥16 years of age usually resident in Auckland (population ≥16 years of age is 1.12 million), during the 12 months from March 1, 2011. All first-ever and recurrent new TIAs (any new TIA 28 days after the index event) during the study period were recorded. Results— There were 785 people with TIA (402 [51.2%] women, mean [SD] age 71.5 [13.8] years); 614 (78%) of European origin, 84 (11%) Māori/Pacific, and 75 (10%) Asian/Other. The annual incidence of TIA was 40 (95% confidence interval, 36–43), and attack rate was 63 (95% confidence interval, 59–68), per 100 000 people, age standardized to the World Health Organization world population. Approximately two thirds of people were known to be hypertensive or were being treated with blood pressure–lowering agents, half were taking antiplatelet agents and just under half were taking lipid-lowering therapy before the index TIA. Two hundred ten (27%) people were known to have atrial fibrillation at the time of the TIA, of whom only 61 (29%) were taking anticoagulant therapy, suggesting a failure to identify or treat atrial fibrillation. Conclusions— This study describes the burden of TIA in an era of aggressive primary and secondary vascular risk factor management. Education programs for medical practitioners and patients around the identification and management of atrial fibrillation are required.

Tissue Plasminogen Activator for Rural Referrals; the Effect of Stroke Team Notification Prior to Arrival

P196 Background: Many rural community hospitals (RCH) in Southwestern Ontario lack a CT scanner. The stroke team (ST) in London provides tertiary care to these RCH. Advance notification of transfer of non-London patients (NLP) from RCH allows the ST to manage them from arrival at the LER. In contrast, the ST is notified of London patients (LP) after their arrival and registration in the London ER (LER). Objective: Assess feasibility of tPA administration to rural patients transferred to a tertiary care center. Methods: Mean symptom to LER, door to imaging, imaging to tPA, and door to tPA (DtPA) for LP and NLP times were compared. In-patients were excluded from the analysis. Results: Between Dec 1, 98 and Jun 30, 00, 61 patients were treated with tPA in London: 16 (26%) were NLP, 45 (74%) were local (37 LP, 8 in-patients). For NLP the mean symptom to RCH time was 37 mins, the mean RCH to LER distance was 41 miles (range 11–80) and the mean transfer time was 90 mins. (range 46–138). Symptom onset to LER time was significantly longer for NLP, but door to imaging, imaging to tPA, and DtPA were significantly lower (p Conclusions: 1. The establishment of a network of RCH and a tertiary center can extend the benefits of tPA to a rural population. 2. DtPA can be shortened if the ST manages the patients from arrival to the ER. This strategy could be applied to local patients if EMS notifies the ST of potential candidates for tPA.

Asymptomatic carotid stenosis

Asymptomatic Carotid Stenosis To the Editor: The recent publication of ACST confirmed the findings from a previous randomized controlled trial that carotid endarterectomy reduces the number of strokes in patients with asymptomatic carotid stenoses.1,2 These findings could be interpreted as a basis for screening for carotid artery stenoses and the widespread expansion of carotid interventions in patients with asymptomatic disease. The report by Goessens and colleagues highlights important issues in the management of such asymptomatic arterial stenoses.3 The authors identify 50% carotid artery stenoses in 8% of patients with symptoms of arterial disease at other sites. Carotid artery narrowing was predictive of vascular death and myocardial infarction but not ischemic stroke during subsequent follow-up. In the 221 patients with 50% carotid artery stenoses the authors report 51 deaths, 28 myocardial infarctions and only 6 ischemic strokes during mean follow-up of 4 years. Thus, only 7% of the serious clinical events were strokes in patients with 50% carotid artery stenoses. In fact, the incidence of ischemic stroke was similar in those patients without 50% carotid artery stenoses. The authors state that this low rate of stroke was achieved despite no patients undergoing carotid intervention. I note from Table 3 of the study by Goessens et al that 22 patients had some form of carotid intervention presumably because of symptom development.3 Pathology studies from the coronary and to a lesser degree from the carotid circulation suggest that atherothrombotic events result from rupture or erosion of the fibrous cap which can occur in minimally as well as severely stenotic atheroma.4 Examination of data from ACST and NASCET emphasizes the importance of symptoms in the selection of patients for carotid intervention1,5 (Table). The data emphasizes the higher risk of stroke associated with symptomatic carotid atherosclerosis even if the stenosis is not significant ( 50%). The actual risk associated with symptomatic carotid atherosclerosis is likely to be higher than depicted in the Table because in the North American trial patients were enrolled if they had experienced a neurological event within 6 months.5 Population studies suggest that up to 32% of patients with 50% carotid stenosis have a stroke within 12 weeks of a neurological event and before carotid intervention.6 These data and that presented by Goessens et al suggest that the main health measures that will substantially improve the prognosis of patients with carotid atherosclerosis are: (1) more urgent presentation and management of symptomatic carotid atherosclerosis; (2) optimization of medical management of atherosclerosis in order to reduce the risk of myocardial infarction and vascular death. Continued efforts to identify imaging or blood findings which predict plaque rupture in asymptomatic patients are also warranted.