L'escalier canadien

Kathleen Daly (1898-1994), a Canadian artist painted this awkward staircase and the dysfunctional corner which is a thing of beauty using oil on canvas. Courtesy of the National Gallery of Canada. (http://www.gallery.ca/en/), Ottawa, Ontario

Published by JAMA 2015 Vol 313:226-227

Screening for Asymptomatic Carotid Artery Stenosis

Developer: US Preventive Services Task Force (USPSTF)

Release date: July 8, 2014

Prior version: December 18, 2007

Funding source: US Agency for Healthcare Research and Quality (AHRQ)

Target population: Asymptomatic adults in the general population

Major recommendation: Do not screen for asymptomatic carotid artery stenosis in the general adult population (Grade D recommendation)

The ENDOSTROKE Study

Singer et al in a study that was conducted at six centers and published in Radiology assessed the significance and role of collateral circulation in160 patients with proximal middle cerebral artery (MCA) occlusion; The ENDOSTROKE study.

Collateral vessel status was assessed at angiography by using the American Society of Interventional and Therapeutic Neuroradiology (ASITN) Society of Interventional Radiology (SIR) collateral vessel grading system, while using the Thrombolysis in Cerebral Infarction (TICI) scale assessed reperfusion. Good outcome was defined as a modified Rankin Scale score of 0–2 at follow-up.

Good clinical outcome was attained in 62 (39%) of the 160 patients, and TICI 2b–3 reperfusion was achieved in 94 (59%) patients. Nineteen patients had ASITN/SIR collateral vessel grades of 0 or 1, 63 patients had a grade of 2, and 78 patients had grades of 3 or 4.

Better collateral vessels were associated with higher reperfusion rates (21%, 48%, and 77% for ASITN/SIR grades of 0 or 1, 2, and 3 or 4, respectively; P < .001), a higher proportion of infarcts smaller than one-third of the MCA territory (32%, 48%, and 69% for ASITN/SIR grades of 0 or 1, 2, and 3 or 4, respectively; P < .001), and a higher proportion of good clinical outcome (11%, 35%, and 49% for ASITN/SIR grades of 0 or 1, 2, and 3 or 4, respectively; P = .007). At multivariable analysis, collateral vessel status independently predicted reperfusion, final infarct size, and clinical outcome. Within an onset-to-treatment time (OTT) of 0–3 hours, collateral vessel status predicted final infarct size and reperfusion. Within an OTT of 3–6 hours, it additionally predicted clinical outcome, with 53% of patients with ASITN/SIR grades of 3 or 4 having a good outcome, as compared with 0% of patients with grades of 0 or 1 and 27% of patients with a grade of 2 (P = .008).

The researchers concluded that collateral circulation independently predicted parameters such as reperfusion, infarct size, and clinical outcome.

CT identifies TIA patients at high risk for Stroke

Wasserman et al in a study published by the journal Stroke report that computed tomography (CT) findings can predict subsequent stroke on patients with transient ischemic attacks (TIA).

Their multicenter prospective cohort study enrolled a total of 2028 patients; 814 of who had ischemic changes on CT and were patients with a clinical diagnosis of an transient ischemic attack or non-disabling stroke and had CT scanning within 24 hours of the event. Primary outcome was subsequent stroke within 90 days. Secondary outcomes were stroke at ≤2 or >2 days. CT findings were classified as acute or chronic ischemia present or absent and or microangiopathy.

The stroke rate was 3.4% at 90 days and 1.5% at ≤2 days. Stroke risk was greater if baseline CT showed acute ischemia alone (10.6%; P=0.002), it was higher in patients with CT findings of acute and chronic ischemia (17.4%; P=0.007), and in those with acute ischemia and microangiopathy (17.6%; P=0.019), and the highest when CT findings of all three acute, chronic ischemia and microangiopathy were present (25.0%; P=0.029).

They concluded that patients with transient ischemic attack/non-disabling stroke, subtle CT findings of acute ischemia alone or acute ischemia with chronic ischemia or microangiopathy were associated with increased subsequent stroke risk between 10-25% within 90 days. 

Mechanical Thrombectomy in Ischemic Strokes; the MR CLEAN trial

Berkhemer et al report in NEJM the results of a Multicenter Randomized Clinical Trial of Endovascular Treatment of Acute Ischemic Stroke in the Netherlands (MR CLEAN) that included patients with severe stroke and proximal-vessel occlusion.  The patients with acute ischemic stroke were randomly assigned to receive intra-arterial treatment plus usual care or usual care alone. Eligible patients had a proximal arterial occlusion in the anterior cerebral circulation that was confirmed on vessel imaging and could be treated within 6 hours after the onset of symptoms.

The primary outcome was evaluated based on the modified Rankin scale score at 90 days; this categorical scale measures functional outcome, with scores ranging from 0 (no symptoms) to 6 (death).

The study involved 500 stroke patients whose mean age was 65 years (23-96).  They were treated at 16 medical centers in the Netherlands with 233 assigned to intraarterial treatment while 267 to usual care alone.   Before the randomization 445 of (89.0%) were treated with intravenous alteplase, a tissue plasminogen activator. Retrievable stents were used to snare and remove the thrombus in 190 of the 233 patients (81.5%) assigned to intra-arterial treatment.  There was an absolute difference of 13.5 percentage points in the rate of functional independence (modified Rankin score, 0 to 2) in favor of the intervention (32.6% vs. 19.1%) after three months. There were no significant differences in mortality or the occurrence of symptomatic intracerebral hemorrhage about 19% in both groups at one month.

They concluded that in patients with acute ischemic stroke caused by a proximal intracranial occlusion of the anterior circulation, intra-arterial treatment administered with a mechanical device within 6 hours after stroke onset was effective and safe.