Introduction: Speed is critical in fibrinolytic therapy for acute ischemic stroke (AIS), but rapid decision-making may increase tPA use in stroke mimics. Complications from lytics in mimic patients, though uncommon, can be severe. Mimic treatment rates when using non-contrast CT as the only initial imaging modality have increased to as high as 34% with intensified efforts to reduce door to needle (DTN) times. Efficient imaging with MRI or multimodal CT may potentially avoid high mimic treatment rates without prolonging treatment.
Methods: In a prospectively maintained registry, we examined all patients treated with IV tPA from January 2010 to June 2015. Institutional policy was to perform MRI first in AIS patients and start tPA on the MR table after DWI showed ischemia and GRE excluded hemorrhage; if MRI could not be performed, multimodal CT with CTA and CTP was performed.
Results: Among 319 IV tPA treated patients, age was 71 (±15), 50% were female, and NIHSS was 13.3 (±8.0). Imaging modality before tPA was MR in 193 (61%) and CT in 126 (39%). In the entire population, the DTN time was 54 (IRQ 42-73) mins and the proportion of mimic patients was 3.1%. DTN times decreased steadily throughout the 5.5 year study period, and did not differ among patients imaged with MR vs CT (Figure). The reduction in DTN times was not associated with an increase in mimic-treated rates (Figure). Among the mimic patients, final diagnoses were migraine - 4, seizure - 3, meningitis - 1, PE - 1, and cardiac dysrhythmia - 1. Imaging modalities in mimic patients were MRI in 5 and CT in 5. Preliminary imaging reads suggested abnormality in 2/10, but final reads were normal in all. In 3/10 mimic patients, tPA infusions were stopped before full dose when ongoing imaging further clarified diagnosis.
Conclusion: A rapid stroke assessment protocol using MRI or multimodal CT permits swift start of thrombolytic therapy and low rates of stroke mimic treatment.
Figure. Door-to-needle time and percent stroke mimics by year.