(Stroke. 2000;31:2920.)
© 2000 American Heart Association, Inc.
Original Contribution |
From the Division of Neurology (K.M.C., A.R.W., D.C.C.J., J.B., P.A.T.), the Department of Radiology (D.G.), and the Department of Medicine (M.S.), Vancouver Hospital and Health Sciences Center, University of British Columbia, Vancouver, Canada.
| Abstract |
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MethodsA combined retrospective and prospective review is presented of 46 consecutive patients treated with intravenous tPA at our hospital with a treatment protocol similar to that of the National Institute of Neurological Disorders and Stroke (NINDS) trial.
ResultsSymptomatic intracranial hemorrhage at 36 hours occurred in 1 patient (2.2%). The median time to treat was 165 minutes, with a median "door-to-needle" time of 84 minutes. Compared with patients presenting initially at our hospital, patients transferred from another institution for tPA therapy were treated closer to the 3-hour time window (mean 173 versus 148 minutes, P<0.001) but had a shorter door-to-needle time (43 versus 102 minutes, P<0.001). For every 10 minutes closer to the 3-hour time window that any patient arrived at the hospital, 7 minutes was saved in the door-to-needle time (correlation coefficient 0.9, P<0.001). Patient outcome did not differ from that in the NINDS trial (P>0.75).
ConclusionsOur safety and patient outcome data compare favorably with NINDS and Phase IV data. Although a 3-hour treatment window was feasible, the median door-to-needle time lengthened as more treatment time was available and the door-to-needle time was beyond recommended standards. This review has prompted changes in our community to improve treatment efficiency.
Key Words: Canada stroke, ischemic thrombolytic therapy
| Introduction |
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Health Canada has granted provisional approval for the use of tPA in acute ischemic stroke (February 1999) providing that postmarketing surveillance is in place. Currently, there is very limited experience to address the questions of safety and efficacy of tPA use in our country.11 13 Significant differences in patient access to acute stroke therapy exist in Canada compared with the United States.13 14 Technology and stroke expertise are centralized, restricting thrombolytic use and necessitating protocols for rapid patient transfer to capable sites.
In 1996, we instituted a tPA protocol, established a hospital stroke team, and developed rapid transfer policies at local referring hospitals. The purpose of the present study was to assess our centers experience with intravenous tPA for acute ischemic stroke by reviewing safety data, the feasibility of a 3-hour time window, and patient outcome in this setting.
| Subjects and Methods |
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We conducted a retrospective chart review of all patients (n=29) receiving intravenous tPA for acute stroke at VHHSC from May 1996 to February 1999 and a prospective review of all patients treated subsequent to the Canadian approval of tPA for acute ischemic stroke to January 1, 2000 (n=17). A tPA protocol based on established guidelines was used and approved by the hospital ethics committee.1 13 15 16 Patients were generally excluded if the initial CT scan demonstrated hemorrhage, significant mass effect, or early signs of infarction suggesting involvement of >1/3 of the middle cerebral artery (MCA) territory.3 Informed consent was obtained from the patient and/or family member in all cases. Patients underwent a CT scan 24 hours after treatment. Additional CT scans were obtained if the patient deteriorated clinically. At the time of treatment, the initial CT scans were evaluated by the stroke neurologist and, when available, a neuroradiologist. Additionally, all available CT scans (n=41) were evaluated retrospectively by one neuroradiologist to determine signs of early infarction and CT scan protocol violations.
Records were reviewed to obtain demographic information, stroke risk factors, admission and maximum blood pressure, time to arrival in the ER, laboratory parameters, and medications. Stroke subtype was determined according to Treatment of Acute Stroke Trial (TOAST) criteria.17 Initial stroke severity was determined by use of the NIH stroke scale (NIHSS).18 The modified Rankin Scale (mRS) and Barthel Index (BI) scores were recorded at discharge and obtained by subsequent telephone interview in all surviving patients.
Time analyses were performed on the entire group and were also
stratified for mode of hospital arrival (direct to VHHSC versus
transfer from a local hospital). A Kaplan-Meier survival
analysis was used to compare the stroke onset to treatment
times for patients presenting directly to VHHSC and for patients
referred from other hospitals. A log-rank test was performed to
determine whether there was a significant difference between the
treatment times of these subgroups. Similarly, the differences between
the time of stroke onset to ER presentation in each
subgroup were compared. The 4 patients who suffered strokes while they
were inpatients at VHHSC were excluded from the arrival time
analysis. A Fisher exact test was used to compare our
hemorrhage rate with that of the NINDS treatment arm. Patient
outcome and mortality data were compared with data from the NINDS
treatment cohort by use of a
2 test. The
efficiency of the stroke team was assessed by regression
analysis, which related the time required to treat a patient
("door-to-needle" time) with the time lapse from stroke onset to ER
arrival. ANCOVA was used to compare differences between patients
presenting at VHHSC and those referred from elsewhere. ANCOVA was
also applied to the door-to-needle times of these 2 subgroups regressed
on chronological time to determine whether treatment times improved as
more experience was gained.
| Results |
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1.8% of all ischemic strokes seen at our
institution over this time period. The demographics and stroke risk
factors of our patients were similar to those in the treatment group of
the NINDS trial (Table
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Safety
Symptomatic intracranial hemorrhage during the
first 36 hours occurred in 1 (2.2%) patient. The
symptomatic intracranial hemorrhage rate did not
differ significantly from that in the NINDS trial (P=0.50).
The patient with symptomatic intracranial
hemorrhage was 84 years old and had a pretreatment NIHSS of 24.
His maximum blood pressure reading was 170/80 mm Hg, and glucose
was 6.7 mmol/L. The initial CT scan showed signs of early
infarction (<1/3 of the MCA territory) but no mass effect. The 24-hour
CT scan demonstrated a large infarction involving virtually the entire
left MCA territory. There was a parenchymal hemorrhage with
ventricular extension, mass effect, and obstructive
hydrocephalus. The patient died 3 days after treatment. Three other
patients (7%) suffered nonlife-threatening systemic
hemorrhage within 10 days of treatment, 1 of whom required a
transfusion.
Signs of early infarction were noted on 24 of 41 scans available for review, and a dense MCA sign was present in 16 cases. On the 24-hour scan, an acute infarction was apparent in 35 patients. Three patients had initial early infarction in >1/3 of the MCA territory.
Nine protocol violations occurred in 8 patients. There were 5 protocol violations for time >180 minutes (181, 182, 185, 190, and 190 minutes) and 1 protocol violation for administration of intravenous heparin within 24 hours after treatment with tPA. On retrospective review, 3 patients had CT scans with early infarction signs in >1/3 of the MCA territory. In one instance, the treating neurologist recognized the signs and elected to treat. Seven of the 9 protocol violations occurred in the first half of the study.
Feasibility
The median time from stroke onset to treatment for all patients
was 165 (range 70 to 190) minutes. The mean time from stroke onset to
treatment for patients presenting directly to our ER was 148
(median 148) minutes versus 173 (median 176) minutes for patients
transferred from elsewhere (P<0.001). The median time from
arrival to CT scan for all patients was 67 minutes. The median
door-to-needle time for all patients was 84 (range 19 to 140) minutes.
Patients presenting directly to our ER took an average of 46
minutes to arrive and had an average door-to-needle time of 102
minutes. In contrast, it took patients transferred from elsewhere
longer to arrive at our ER (average of 130 minutes), but the average
door-to-needle time was faster at 43 minutes (P<0.001).
Fourteen patients had a door-to-needle time of <60 minutes, all of
whom were transferred from other institutions.
There was an inverse relationship between the time from stroke onset to
ER arrival and the door-to-needle time (Figure 1
). Overall, for each 10-minute delay in
arrival, there was a decrease in the door-to-needle time of 6.7 minutes
(correlation coefficient 0.9, P<0.001). For patients coming
directly to our ER, each 10-minute delay in arrival resulted in a
decrease in the door-to-needle time of 5 minutes (P=0.03).
For patients transferred from other hospitals, each 10-minute delay in
arrival resulted in a decrease in the door-to-needle time of 6 minutes
(P<0.001).
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Four patients in our series were inpatients at VHHSC at the time of stroke onset; 2 strokes occurred in the ER after the patients presented with a transient ischemic attack, and 2 began on a hospital ward. The onset-treatment times in the ER patients were 80 and 65 minutes; the onset-treatment times for the ward patients were 174 and 180 minutes. Both patients whose strokes occurred in the ER were observed for a period of time before treatment to exclude recurrent transient ischemic attack. Delayed treatment of the ward patients was the result of slow stroke service contact time followed by difficulty in initiating thrombolytic therapy in a non-ER setting.
There was no significant improvement in the door-to-needle time over the course of the present study. The most common reasons that tPA was not administered included time >3 hours and spontaneous rapid improvement of stroke symptoms.
Outcome
At the time of hospital discharge, 30% of the patients had a
favorable outcome on the mRS (score 0 to 1), and 37% had a favorable
outcome on the BI (score 95 to 100). At the time of follow-up (median
13 months after stroke), 43% of the patients had a favorable outcome
on the mRS, and 48% had a favorable outcome on the BI (score 95 to
100) (Figure 2
). The differences between
the mRS and BI scores in the VHHSC patients at follow-up compared with
the NINDS treatment group at 1 year were not statistically significant
(mRS, P=0.75; BI, P=0.78).
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Ten patients (22%) died before discharge, which was comparable to 17% at 3 months in the NINDS trial (P=0.46). One hospital death was due to intracranial hemorrhage; 5, to cerebral edema with mass effect; 2, to respiratory failure (1 aspiration pneumonia); 1, to recurrent stroke; and 1, to multiorgan failure (congestive heart failure and renal failure). Two of the patients who died before discharge had protocol time violations (181and 185 minutes). At 13 months, 22% of our patients were dead. This did not differ from the NINDS 1-year treatment cohort (24%, P=0.73).
| Discussion |
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Our symptomatic intracranial hemorrhage rate was lower than that seen in the NINDS trial; however, the difference was not statistically significant. Although we had only a small number of patients in our series, this trend may be due to our treatment protocol, which was based on recommendations from several sources; thus, other "safety features" were added, most notably the CT exclusion criteria. We recognize that exclusion of patients with early infarction signs in >1/3 of the MCA territory is controversial among stroke specialists because these patients were included in the successful NINDS trial. However, ECASS I clearly demonstrated that the risk of hemorrhage increases if signs of early infarction are seen in >1/3 of the MCA territory before treatment (OR 3.5).3 Also, within ECASS I, most protocol violations involved treatment of patients who had CT exclusions, underscoring the difficulty in early CT interpretation. In our series, 2 patients were unknowingly treated in this situation. ECASS II demonstrated improved CT interpretation with pretrial radiology courses, suggesting that practice improves skills.4 Limiting the number of treating neurologists combined with attempts to review the films with a neuroradiologist when available may have minimized the number of CT treatment violations in our series.
The NINDS group has recently addressed the need for rapid administration of tPA. They demonstrate that tPA efficacy is time dependent. The OR for excellent outcome approaches 1.0 when treatment occurs near the 3-hour mark.20 In view of evidence suggesting that faster treatment yields better outcome, our median time to treatment of 165 minutes leaves room for improvement. Guidelines recommend a door-to-needle time of 1 hour.15 This target was achieved in 14 of 46 patients in our series, all of whom were transferred from other facilities. In this situation, the stroke neurologist and radiology department had advanced warning of the arrival of a transferred patient, resulting in a faster door-to-needle time. Although the door-to-needle time was significantly faster for these transferred patients, the median time from stroke onset to treatment was 28 minutes longer than in patients presenting directly to VHHSC.
Review of our series has demonstrated difficulties with timely thrombolysis, particularly in the cohort of patients transferred from other hospitals. Lack of CT scan availability and stroke expertise in our health care region necessitates patient transfer. It is unlikely that improving efficiency at our hospital will significantly shorten treatment times in the transferred patient group. Therefore, we have initiated strategies to shorten the time to arrival at our ER, including upgraded priority for ambulance response and stroke transfer combined with educational programs for local emergency physicians and nurses. Future projects include the creation of a destination hospital policy in addition to education of ambulance attendants and the public regarding stroke recognition. The major delay in treating patients presenting directly to our hospital occurred before CT scan. Most patients in this series were referred after ER physician assessment. Within our hospital, we have implemented rapid nursing and ER physician triage protocols to improve the time to stroke team notification. Although the number of in-hospital strokes was small (2 ward strokes), these patients had major delays in treatment (mean onset-treatment time 177 minutes) that were due to slow stroke team notification and problematic tPA use in a non-ER setting. Wards and physicians have been supplied with educational information describing the stroke team. Analysis of this series has therefore enabled us to implement changes to streamline therapy.
In general, a number of factors contribute to the delay in door-to-needle time, including ER triage, availability of a CT scanner and laboratory results, consultation with other physicians, and treatment of hypertension.8 Furthermore, our series confirms the finding in STARS that as the length of time available to treat increases, the door-to-needle time increases as well.10 In our series, almost 7 minutes less time was required to treat for each 10 minutes closer to the end of the 3-hour time window the patient arrived. Thus, we were capable of rapid treatment when necessary, but we procrastinated when more time was available.
Stroke physicians need to be aware of the "human" variable of procrastination. Human nature is such that there is increasing motivation to complete a task as a deadline approaches.21 Therefore, better emphasis of several deadlines may improve treatment time. To overcome the procrastination factor, we are instituting a time sheet for each patient (target times, derived from the Advanced Cardiac Life Support guidelines, are bracketed). Times recorded include the following: onset, ER arrival, door to triage (5 minutes), door to stroke team notification (10 minutes), door to ER physician assessment (10 minutes), door to CT (25 minutes), and door to treatment (60 minutes). Stroke team review of each case is expected to improve performance. The NINDS investigators feel that periodic review is beneficial.15
Our outcome data are similar to the NINDS trial follow-up data at 1 year.2 There is no difference in our mortality rate at follow-up (median 13 months, mortality 22%) compared with the NINDS treatment group at 1 year (mortality 24%, P=0.73). Because our series is not blinded and because there is no control group, we cannot provide evidence for the efficacy of treatment. In addition, the retrospective nature of the present study has inherent limitations.
In summary, in a Canadian teaching hospital setting, our safety and patient outcome data compare favorably with NINDS and Phase IV data. The median door-to-needle times lengthened as more treatment time was available and the door-to-needle time was beyond recommended standards. The present review has enabled us to confirm safety and improve efficiency.
| Acknowledgments |
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| Footnotes |
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Received May 11, 2000; revision received August 9, 2000; accepted August 9, 2000.
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