Prevalence of Imaging Targets in Patients With Minor Stroke Selected for IV tPA Treatment Using MRI: The Treatment of Minor Stroke With MRI Evaluation Study (TIMES).

OBJECTIVE: To determine the IV tissue plasminogen activator (tPA) treatment rate of patients with minor acute ischemic stroke (mAIS) at our centers and compare the frequency of MRI targets by treatment stratification and clinical severity, we evaluated clinical characteristics and baseline MRIs for tPA-treated and untreated patients. METHODS: Patients with ischemic stroke from 2015 to 2017 with admit NIH Stroke Scale (NIHSS) <6 were considered. The treated cohort received standard IV tPA and was screened with baseline MRI. The untreated cohort received no acute intervention and baseline MRI was <4 hours from onset. Patients were stratified into "clearly" and "not clearly" disabling deficits by NIHSS elements. Baseline MRI was evaluated by independent raters for AIS targets, with frequencies compared between groups. RESULTS: Of 255 patients with mAIS ≤4.5 hours from onset, 140 (55%) received IV tPA, accounting for 46% of all IV tPA patients (n = 305). Eighty-five percent (n = 119) were screened with baseline MRI and had significantly more frequent imaging targets compared to those untreated (n = 90). Of this treated cohort, 75% (n = 89) were not clearly disabling. Except for perfusion-diffusion mismatch (81% clearly disabling vs 56% not clearly disabling [p = 0.036]), there were no significant differences in the frequency of imaging targets across the treated cohort stratified by clinical severity. CONCLUSIONS: In MRI-screened mAIS, imaging targets were more frequently seen in patients treated with IV tPA, with similar frequencies even in those without clearly disabling deficits. MRI targets could be used to guide thrombolytic therapy in patients with mAIS; however, a randomized trial is needed to demonstrate efficacy.

Routine use of FLAIR-negative MRI in the treatment of unknown onset stroke.

BACKGROUND: Treatment of FLAIR-negative stroke in patients presenting in an unknown time window has been shown to be safe and effective. However, implementation can be challenging due to the need for hyper-acute MRI screening. The purpose of this study was to review the routine application of this practice outside of a clinical trial. METHODS: Patients presenting from 3/1/16 to 8/22/18 in a time window <4.5 h from symptom discovery but >4.5 h from last known normal were included if they had a hyper-acute MRI performed. Quantitative assessment based on the MR WITNESS trial and qualitative assessment based on the WAKE-UP trial were used to grade the FLAIR images. The MR WITNESS trial used a quantitative assessment of FLAIR change where the fractional increase in signal change had to be <1.15, whereas the WAKE-UP trial used a visual assessment requiring the absence of marked FLAIR signal changes. RESULTS: During the study period, 136 stroke patients presented and were imaged in the specified time window. Of these, 17 (12.5%) received IV tPA. Three patients had hemorrhage on 24-h MRI follow up; none had an increase in NIHSS ≥4. Of the 119 patients who were screened but not treated, 18 (15%) were eligible based on FLAIR quantitative assessment and 55 (46%) were eligible based on qualitative assessment. In all cases where patients were not treated, there was an identifiable exclusion based on trial criteria. During the study period, IV tPA utilization was increased by 5.6% due to screening and treating patients with unknown onset stroke. CONCLUSIONS: Screening stroke patients in an unknown time window with MRI is practical in a real-world setting and increases IV tPA utilization.

MRI-based thrombolytic therapy in patients with acute ischemic stroke presenting with a low NIHSS.

OBJECTIVE: Treatment of patients with stroke presenting with minor deficits remains controversial, and the recent Potential of rtPA for Ischemic Strokes with Mild Symptoms (PRISMS) trial, which randomized patients to thrombolysis vs aspirin, did not show benefit. We studied the safety and efficacy of thrombolysis in a population of patients with acute stroke presenting with low NIH Stroke Scale (NIHSS) scores screened using MRI. METHODS: The NIH Natural History of Stroke database was reviewed from January 2006 to December 2016 to identify all patients with an initial NIHSS score ≤5 who received thrombolysis within 4.5 hours of symptom onset after being screened with MRI. The 24-hour postthrombolysis MRIs were reviewed for hemorrhagic transformation. Primary outcomes were symptomatic intracranial hemorrhage (sICH) and favorable 90-day outcome modified Rankin Scale score 0-1. Subgroup analysis was performed on patients who would have been eligible for the PRISMS trial, which enrolled patients with a nondisabling neurologic deficit. RESULTS: A total of 121 patients were included in the study with a median age of 65 and an NIHSS score of 3; 63% were women. The rate of any hemorrhagic transformation was 13%, with 11% of them being limited to petechial hemorrhage. The rate of sICH was <1%. Sixty-six patients had 90-day outcome data; of those, 74% had a favorable outcome. For the subgroup of 81 PRISMS-eligible patients, none experienced sICH. Fifty of these patients had 90-day outcome data; of these, 84% had a favorable outcome. CONCLUSIONS: Thrombolytic therapy was safe in our patients with stroke with minor deficits who were initially evaluated by MRI. Future studies of this population may benefit from MRI selection. CLASSIFICATION OF EVIDENCE: This study provides Class IV evidence that for patients with acute ischemic stroke and NIHSS ≤5 screened with MRI, IV tissue plasminogen activator is safe.

The therapeutic value of laboratory testing for hypercoagulable states in secondary stroke prevention.

Although screening for hypercoagulable states is commonly performed as part of the evaluation of first arterial ischemic stroke in young adults, available evidence does not support this as a routine practice, even in patients with cryptogenic stroke and a positive family history of early thrombotic events or in patients with a patent foramen ovale. Testing for antiphospholipid antibodies is a possible exception because persistent antibodies are associated with an increased risk of recurrent stroke. Despite the lack of supporting data, screening for hypercoagulable states in recurrent early-onset cryptogenic cerebral ischemia could be considered.