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

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.

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.

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.

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.

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.