Trimming the fat in acute ischemic stroke: an assessment of 24-h CT scans in tPA patients.

BACKGROUND: International management of acute ischemic stroke patients treated with intravenous tissue plasminogen activator frequently includes 24-h head imaging. These recommendations stem from the National Institute of Neurological Disorders and Stroke (NINDS) clinical trial protocol regarding the risk of intracerebral hemorrhage post-tissue plasminogen activator administration. Follow-up computed tomography scans on select patients, however, may not effect clinical management, resulting in unnecessary radiation exposure and healthcare costs. AIMS: Our study questions the utility of routine 24-h computed tomography imaging and looks at the National Institute of Health Stroke Scale as a possible clinical screen for selecting candidates for 24-h imaging. Such a tool would result in decreased radiation exposure to the patient and decreased cost to the hospital.
METHODS: Consecutive patients with acute ischemic stroke given intravenous tissue plasminogen activator between June 2008 and December 2011 were retrospectively identified and dichotomized based on change in 24-h National Institute of Health Stroke Scale from baseline. Initial analysis compared patients with National Institute of Health Stroke Scale worsening to those without worsening. Subsequent analysis was limited to patients with a baseline National Institute of Health Stroke Scale ≤10. Baseline demographics and medical history, baseline and 24-h computed tomography findings, medical and/or surgical orders within six-hours of imaging, and antithrombotic administration within 24-48-h postintravenous tissue plasminogen activator were compared between the two groups.
RESULTS: Two-hundred patients met inclusion criteria: No 24-h National Institute of Health Stroke Scale worsening (n = 167) vs. 24-h National Institute of Health Stroke Scale worsening (n = 33). No baseline demographic or admission data differed significantly between the two groups. Patients without 24-h National Institute of Health Stroke Scale worsening had significantly lower incidence of hemorrhagic infarction (10·8% vs. 31·3%, P = 0·0014) on follow-up imaging. Less than 2% of all patients without 24-h National Institute of Health Stroke Scale worsening had a parenchymal hematoma. No patient with baseline National Institute of Health Stroke Scale ≤10 and without 24-h National Institute of Health Stroke Scale worsening had parenchymal hematoma. Patients with 24-h worsening were significantly less likely to receive timely antithrombotic therapy (60·6% vs. 77·8%, odds ratio 0·44, 95% confidence interval 0·20-0·96).
CONCLUSIONS: Our results demonstrate that routine 24-h computed tomography scan in patients without 24-h National Institute of Health Stroke Scale worsening (especially those with baseline National Institute of Health Stroke Scale ≤10) is less likely to yield information that results in a deviation from standard acute stroke care. No patient without worsening and baseline National Institute of Health Stroke Scale ≤10 had parenchymal hematoma on 24-h computed tomography. Application of the National Institute of Health Stroke Scale to distinguish patients who should have 24-h follow-up imaging from those who will not benefit is a potential avenue for improving utilization of resources and warrants further study.