Quantifying candidate volume for endovascular therapy for acute ischemic stroke: a retrospective chart review

Brian Lauzon; Catherine Corrigan-Lauzon; Jonathan Grynspan; Susan Bursey; Timo Krings; Padma Puranam

doi:10.9778/cmajo.20180057

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Figure 1:
Distribution of hospitals and health centres in northeastern Ontario. Each hospital or health centre is represented by a coloured square. The number inside the square represents the number of discharges from that institution in 2016 for patients with ischemic stroke. The blue square represents Health Sciences North. Green squares represent centres within a 2-hour transport radius to Health Sciences North by land ambulance. Orange squares represent centres within a 2-hour transport radius to Health Sciences North by air ambulance. Red squares represent centres outside the 2-hour transport time to Health Sciences North by air or land ambulance. The 5 larger squares, including Health Sciences North, represent centres with computed tomography angiography capabilities that administer tissue plasminogen activator. Air ambulance transport times were determined in consultation with Paramedic Services for the City of Greater Sudbury. Not pictured: Cochrane-James Bay district, which had 1 ischemic stroke discharge from the Weeneebayko Area Health Authority in 2016.

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Table 1:

Demographic and clinical characteristics for patients who presented to the emergency department at Health Sciences North with ischemic stroke symptoms between May 1, 2016, and Apr. 30, 2017^*

Characteristic	No. (%) of patients^†	n = 71 Median (IQR)
Age, yr	71	67 (58–81) range: 38–92
Sex
Men	44 (62)	NA
Women	27 (38)	NA
Time intervals, hh:mm^‡
From onset to presentation^§
Patients with sudden-onset stroke, non–bypass protocol^¶	47 (66)	1:30 (0:51–2:49)
Patients with stroke on awakening	5 (7)	4:35 (4:15–8:52)^††
Patients with bypass protocol or who presented to other ED	12 (17)	2:28 (1:57–4:40)
From presentation to imaging^**	71 (100)	0:12 (0:06–0:41)
From presentation to assessment by stroke on-call physician^**	66 (93)	0:39 (0:24–1:11)
NIHSS, mean score ± SD	7.04 ± 6.50	NA
Score 0–4	24 (34)	NA
Score 5–14	16 (23)	NA
Score 15–24	5 (7)	NA
Score ≥ 25	2 (3)	NA
Not available or not completed	24 (34)	NA
Prestroke functionality
Independent	66 (93)	NA
Required assistance	5 (7)	NA
Dependent	0 (0)	NA
Received tPA	28 (39)
Time from presentation to tPA, hh:mm	26	0:59 (0:50–1:25)
Time from stroke onset to tPA, hh:mm	27	3:06 (2:06–4:09)

Note: ED = emergency department, hh:mm = hours:minutes, IQR = interquartile range, NA = not applicable, NIHSS = National Institutes of Health Stroke Scale (completed at time of stroke on-call assessment), SD = standard deviation, tPA = tissue plasminogen activator.
↵* All patients presented within 24 h of symptom onset, and all were assessed by a stroke on-call physician.
↵† Except where indicated otherwise.
↵‡ For determination of time intervals, presentation is defined as the time of arrival to hospital.
↵§ For time from onset to presentation, in-house strokes were not included. For patients with stroke on awakening, time to presentation is from the time the patient was last observed in a normal state.
↵¶ Bypass protocol was defined as presentation to an ED in the Health Sciences North catchment area (Manitoulin, Espanola, Elliot Lake) or bypass of those EDs by emergency medical services, with patients being brought directly to Health Sciences North.
↵** For in-house strokes, time to imaging and time to assessment are from onset of the stroke.
↵†† Time from onset to presentation was significantly greater for patients with stroke on awakening than for those with sudden-onset stroke (p < 0.01 by 2-tailed t test).

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Table 2:

Imaging data for patients with symptoms of ischemic stroke^*

Imaging metric	No. (%) of patients^†
ASPECTS	n = 53
Mean score ± SD	8.89 ± 1.86
Range	1–10
Multiphasic CT angiography	n = 71
Completed upon presentation	51 (72)
Completed > 12 h after presentation	6 (8)
Not completed	14 (20)
Site/type of occlusion	n = 51
Carotid T	1 (2)
Carotid L	1 (2)
M1–MCA	9 (18)
M1–MCA equivalent (≥ 2 M2–MCAs)	2 (4)
Basilar artery (basilar tip)	1 (2)
No proximal-vessel occlusion	37 (72)
Quality of collateral circulation^‡	n = 14
Good	12 (86)
Intermediate	2 (14)
Poor	0 (0)
Vascular access^‡	n = 14
Suitable/feasible	12 (86)
Unsuitable	2 (14)

Note: ASPECTS = Alberta Stroke Programme Early CT Score, CT = computed tomography, M1–MCA = M1 segment of middle cerebral artery, M2–MCA = M2 segment of middle cerebral artery, SD = standard deviation.
↵* All patients presented within 24 h of symptom onset, and all were assessed by a stroke on-call physician. Radiographs were assessed by a staff radiologist at Health Sciences North if both unenhanced CT of the head and multiphasic CT angiography of the head and neck were completed within 12 h of presentation to the emergency department.
↵† Except where indicated otherwise.
↵‡ Quality of collateral circulation and feasibility of vascular access were not determined for patients with no proximal-vessel occlusion identified on CT angiography.

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Table 3:

Candidacy for endovascular therapy on the basis of clinical factors, for patients with acute ischemic stroke presenting within 24 h of symptom onset^*

Clinical candidacy	No. (%) of patients n = 71
Yes	22 (31)
No	49 (69)
NIHSS score < 5	23 (47)
NIHSS score not available	20 (41)
> 12 h from onset to presentation	3 (6)
Not functionally independent before stroke	3 (6)

Note: NIHSS = National Institutes of Health Stroke Scale.
↵* All patients were seen by a stroke on-call physician upon presentation.

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Table 4:

Candidacy for endovascular therapy on the basis of imaging results, for patients with acute ischemic stroke presenting within 24 h of symptom onset^*

Imaging candidacy	No. (%) of patients n = 71
Yes	11 (15)
No	60 (85)
No proximal-vessel occlusion	36 (60)
Multiphasic CT angiography not completed upon presentation	20 (33)
Unsuitable proximal-vessel access	2 (3)
Extensive early ischemic changes on CT	2 (3)

Note: CT = computed tomography.
↵* All patients were seen by a stroke-on-call physician upon presentation.

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Table 5:

Candidacy for endovascular therapy on the basis of clinical and imaging data combined, for patients with acute ischemic stroke presenting within 24 h of symptom onset^*

Candidacy for endovascular therapy	No. (%) of patients n = 71
Clinical candidacy	22 (31)
Imaging candidacy	11 (15)
Combined clinical and imaging candidacy	9 (13)
Site of occlusion (candidates only)
Carotid T	1 (11)
M1–MCA	6 (67)
M1–MCA equivalent (≥ 2 M2–MCAs)	1 (11)
Basilar artery (basilar tip)	1 (11)
Modified Rankin scale score 90 d after stroke, mean ± SD^†	5.5 ± 1.2

Note: M1–MCA = M1 segment of middle cerebral artery, M2–MCA = M2 segment of middle cerebral artery, SD = standard deviation.
↵* All patients were seen by a stroke on-call physician upon presentation.
↵† Modified Rankin scale scores at 90 days after stroke were calculated for the 6 candidates deemed suitable by both clinical and imaging criteria for whom sufficient data were available to calculate the score.