CT Angiography in Patients with Minor Strokes

A paper published in Radiology reports that CT angiography in patients with acute minor strokes was found to be beneficial in patients who are candidates for thrombectomy. 

The searchers stated that while minor strokes represent up to two-thirds of all cases of acute ischemic strokes, it's unknown whether CT angiography (CTA) to evaluate large-vessel occlusion in patients with minor stroke is cost-effective.

Large vessel occlusion is present in around 18% of patients with National Institutes of Health Stroke Scale (NIHSS) scores of 0-4 and 39% of patients with NIHSS scores of 5-8, but the authors said CTA is only recommended as a cost effective study to triage patients with acute minor stroke and find potential candidates for mechanical thrombectomy.  

The authors concluded that screening for large vessel occlusion with CTA in patients with acute minor stroke is cost effective and is associated with better outcome .

Cardiac CT as effective as TEE in predicting recurrent strokes

Transesophageal echocardiography (TEE) is the imaging modality of choice in the detection of source of emboli in patients with ischemic stroke.  Cardiac CT is just as effective at predicting recurrent strokes, according to a study published in Radiology.

Lee et al analyzed the studies of 548 consecutive patients, 374 of whom had ischemic stroke (254 men and 120 women, with a mean age of 63.1 years) who underwent TEE and cardiac CT. TEE and cardiac CT images were assessed for cardioembolic sources, including thrombus, tumor, spontaneous echo contrast, valvular vegetation, atrial septal aneurysm, patent foramen ovale, and aortic plaque. The primary end point was stroke recurrence.

Twenty-eight of the patients had stroke recurrence in the two-year period following their initial strokes. The researchers analyzed the information from their scans and found that complex aortic plaque was associated with increased risk of recurrence.  

Cardiac CT was equally as effective as TEE as a predictive tool for recurrent strokes.

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.

Ambulance-Based Thrombolysis in Acute Ischemic Stroke

Ebinger et al report in JAMA the result a specialized ambulance has in the initiation of treatment in patients with acute ischemic strokes.

Their study was conducted in Berlin, Germany over a 21 months period between 2011 and 2013 when a Stroke Emergency Mobile (STEMO) unit was dispatched every other week to care of patients with strokes. The STEMO was an ambulance equipped with a CT scanner, point-of-care laboratory, with telemedicine connection, a physician, a paramedic and an x-ray technician. Thrombolysis was started before transport to hospital if ischemic stroke was confirmed and contraindications excluded.  During the study period 6182 adult patients were included.

There was a reduction of 25-minutes in alarm-to-treatment times for STEMO compared to control weeks.  The 25-minute reduction was due to faster alarm-to-imaging and imaging-to-treatment intervals. Fifty eight percent of patients were treated within 90 minutes of onset versus 37% in the control.  The intervention also resulted in 33% patients treated with tPA versus 21% in the control.  STEMO deployment incurred no increased risk for intra-cerebral hemorrhage (7/200 vs 22/323); or 7-day mortality (9/199 versus 15/323).

A prior study by Walter et al¹ who also used a mobile stroke unit and treated patients with acute ischemic stroke with tPA safely within 70 to 80 minutes.

The authors conclude the use of ambulance-based thrombolysis resulted in decreased time to treatment without an increase in adverse events. 

1.  Walter S, Kostopoulos P,  Haass A et al. Diagnosis and treatment of patients with stroke in a mobile unit versus hospital: a randomized study controlled trial Lancet Neurol. 2012;11(5):397-404