While most facilities are using non-contrast CT, CT angiograms, and/or CT perfusion as part of their initial triage of possible stroke, there are a few using rapid MRI-based protocols. MRI is vastly superior to CT for its specificity for stroke, quite useful in reducing early diagnostic closure and unnecessary treatment with thrombolytics.
One of these MRI-based stroke systems has published a brief, retrospective look at their tPA cohort – focusing, in this report, on the particularly controversial “minor stroke”. Specifically, they teased out patients with presenting NIHSS 0-6, tried to classify them as “clearly disabling”, “potential disabling”, and “non-disabling”. Then, they looked at 90-day outcomes from these groups, trying to discern any useful conclusions regarding the efficacy and safety of tPA in these patients.
Over the 2015-17 study period, there were 1,440 patients evaluated for potential stroke treatment. Of these, 792 fell into their “minor stroke” definition – only 255 of which received a provisional diagnosis of acute ischemic stroke. The remainder were diagnosed as stroke mimics, transient ischemic attacks, or intracranial hemorrhage. Of these 255, about 80% were able to be evaluated with MRI as their primary mode of evaluation, and about 3/5ths were treated with tPA. Ultimately, they end up with 119 patients in their primary comparison, looking at features and outcomes of 30 patients with “clearly disabling” deficits and 89 without.
How effective is tPA in this cohort? Who knows! This study doesn’t answer that question in the slightest. There is no untreated population with 90-day outcomes gathered for comparison. The authors mostly use this study to tout MRI-based screening technology, along with descriptive statistics of frequent perfusion abnormalities present in their untreated cohort. The general gist of their discussion is akin to the oculostenotic reflex in cardiac catheterization – if a stenosis is seen, it will be treated, regardless of known benefit. For using MRI to screen for stroke, they tend to wax optimistically the identification of these perfusion abnormalities in non-disabling strokes might better encourage acute treatment.
This ought to be considered nonsense, as tPA treatment of non-disabling strokes remains bereft of evidence of value. And, just to describe the scope of the problem – of the 305 patients treated with IV tPA, 75 did not have “clearly disabling” deficits. A full quarter of the tPA treatment population based on wishes and hopes! There was one upside to screening with MRI, at least: 454 of those 792 with “minor stroke” received a diagnosis of stroke mimic. I shudder to think of the unnecessary carnage at hospitals without the capacity to exclude stroke mimics with such ease.
Non-disabling stroke should never be treated with thrombolysis in clinical practice, not after PRISMS, nor after looking at the NIHSS 0-5 group in IST-3. The new European Stroke Organization guidelines recommend against thrombolysis. Just stop!
“Prevalence of Imaging Targets in Patients with Minor Stroke Select for IV tPA Treatment Using MRI”
https://n.neurology.org/content/96/9/e1301