Utilization of intravenous thrombolysis in 3-4.5 hours: analysis of the Minnesota stroke registry

The American Heart Association and the American Stroke Association recommend intravenous (IV) thrombolysis up to 4.5 h from acute ischemic stroke symptom onset based on its proven benefit in improving patient outcomes. We analyzed data from the Minnesota Stroke Registry to assess the rates of IV thrombolytic utilization and the process of care in this expanded window.

We identified patients who had received IV recombinant tissue plasminogen activator (rt-PA) at any of the 19 participating hospitals from January 1, 2008 till December 31, 2010. Treatment groups were those actually treated by IV rt-PA in 0-3 h and those treated by IV rt-PA in 3-4.5 h. Duration from symptom onset to arrival in the emergency department (ED) was dichotomized to cohorts of 0-2 and 2-3.5 h. We determined the overall utilization of IV rt-PA in the expanded window and calculated door-to-needle times for the two treatment windows. We also ascertained the rates of symptomatic intracerebral hemorrhage between the two treatment groups.

Out of the total 519 patients who received IV rt-PA for acute ischemic stroke, 433 (83%) were treated within 0-3 h and 86 (17%) within 3-4.5 h. Of all the patients who received IV rt-PA within 3-4.5 h, 45% arrived at the ED within 2 h of symptom onset. Median door-to-needle time for the 0- to 3-hour window was 74.5 min [interquartile range (IQR) 57-90] and 54 min (IQR 43.5-70.5) for the 3- to 4.5-hour window. Based on arrival time to the ED, door-to-needle time of ≤60 min was achieved by only 31% (142/458) of patients who arrived within 0-2 h of their symptom onset compared to 61% (37/61) of those who arrived at the ED within 2-3.5 h of their symptom onset. Fifty-nine (14%) patients in the 0- to 3-hour group and 17 (20%) patients in the 3- to 4.5-hour group received a combination of IV rt-PA and endovascular treatments. Among patients with documented admission National Institutes of Health Stroke Scale scores, the values (median with IQR) were different between the 0- to 3- and the 3- to 4.5-hour group, i.e. 10 (IQR 5-18) and 7 (IQR 4-14), respectively.

Patients who received IV rt-PA within the 3- to 4.5-hour window comprised 17% of all IV rt-PA cases treated in the Minnesota Stroke Registry hospitals after the new guidelines recommended a time window expansion. Almost half of these patients would have qualified for treatment within the 0- to 3-hour window as they presented within 0-2 h of symptom onset. Patients arriving 2-3.5 h after symptom onset received thrombolysis on average 20 min faster than patients arriving within 2 h of symptom onset.