Abstract
Background
The presence of sudden onset to maximal deficit (SOTMD) in patients with acute basilar artery occlusion often results in more severe outcomes. However, the effect of endovascular therapy on SOTMD and whether the outcome is affected by onset‐to‐puncture time remain unclear.
Methods and Results
This retrospective analysis was conducted using data from the prospective BASILAR (Endovascular Treatment for Acute Basilar Artery Occlusion Study Registry). Consecutive patients with basilar artery occlusion receiving endovascular therapy were dichotomized into SOTMD and non‐SOTMD cohorts. The primary outcomes included a favorable outcome (modified Rankin scale 0–3), recanalization, and mortality at 90 days. The outcomes of patients with SOTMD were analyzed using multivariable logistic regression. In the multivariate analysis, a favorable outcome was similar between the two cohorts (odds ratio [OR], 0.88 [95% CI, 0.58–1.34]; P=0.5), although the mortality of patients with SOTMD was higher than that of patients with non‐SOTMD (OR, 1.67 [95% CI, 1.14–2.44]; P=0.008). The probability of mortality increased from 40.0% at 1 hour to 70.0% at 6 hours in the SOTMD cohort, and favorable outcomes of patients with non‐SOTMD declined from 38.0% at 1 hour to 18.0% at 8 hours.
Conclusions
No significant difference was observed in favorable outcomes between the SOTMD and non‐SOTMD groups, although mortality was higher in the SOTMD cohort. The patients with SOTMD had a stronger time dependence for endovascular therapy in terms of mortality, while the time dependency regarding favorable outcome in the NSOTMD group was even higher.
Registration
URL: https://www.chictr.org.cn; Unique identifier: ChiCTR1800014759.
Keywords: basilar artery occlusion, endovascular therapy, sudden onset to maximal deficit
Subject Categories: Cerebrovascular Disease/Stroke, Ischemic Stroke
Nonstandard Abbreviations and Acronyms
- ASITN/SIR
American Society of Interventional and Therapeutic Neuroradiology/Society of Interventional Radiology
- ATTENTION
Endovascular Treatment For Acute Basilar Artery Occlusion: A Multicentre Randomised Clinical Trial
- BAO
basilar artery occlusion
- BAOCHE
Basilar Artery Occlusion Chinese Endovascular
- BASICS
Basilar Artery International Cooperation Study
- BASILAR
Endovascular Treatment for Acute Basilar Artery Occlusion Study Registry
- BEST
Acute Basilar Artery Occlusion: Endovascular Interventions vs Standard Medical Treatment
- EVT
endovascular therapy
- mRS
modified Rankin Scale
- mTICI
modified Thrombolysis in Cerebral Infarction
- NIHSS
National Institutes of Health Stroke Scale
- NSOTMD
nonsudden onset to maximal deficit
- OPT
onset‐to‐puncture time
- pc‐ASPECTS
posterior circulation Alberta Stroke Program Early Computed Tomography Score
- PSM
propensity score matching
- SOTMD
sudden onset to maximal deficit
- TOAST
Trial of ORG 10172 in Acute Stroke Treatment
Clinical Perspective.
What Is New?
The effect of endovascular therapy (EVT) on patients with sudden onset to maximal deficit (SOTMD) is still unclear. In our study, no significant difference was observed in favorable outcomes between the SOTMD and non‐SOTMD groups, although the mortality of patients with SOTMD was higher than that of patients with non‐SOTMD.
We found that patients with SOTMD had a stronger time dependence for EVT in terms of mortality, while the time dependency of favorable outcomes in the non‐SOTMD group was even higher.
What Are the Clinical Implications?
Provided new evidence for the benefit of EVT in patients with SOTMD, although the mortality of patients with SOTMD was higher than that the non‐SOTMD group.
Reduced mortality rate was seen in the patients with SOTMD after EVT within 6 hours, while the favorable outcome in the non‐SOTMD group was increased within 8 hours after symptom onset.
After 8 hours, there still seemed to be a relevant benefit for EVT in the non‐SOTMD group; however, performing EVT as soon as possible in all patients with acute basilar artery occlusion is desirable in clinical practice.
Acute basilar artery occlusion (BAO) is a rare cause of stroke and accounts for 5% of large‐vessel occlusion strokes, which are generally associated with a higher mortality if recanalization is not achieved. 1 , 2 Although evidence from the BEST (Acute Basilar Artery Occlusion: Endovascular Interventions vs Standard Medical Treatment) trial failed to support the superiority of endovascular therapy (EVT) over medical management, this was likely due to a high crossover rate and poor study recruitment. 3 In contrast, results from the randomized controlled BASICS (Basilar Artery International Cooperation Study) may not exclude that a substantial benefit is obtained from EVT. 4 Encouragingly, the latest results from two randomized controlled trials (ATTENTION [Endovascular Treatment For Acute Basilar Artery Occlusion: A Multicentre Randomised Clinical Trial] and BAOCHE [Basilar Artery Occlusion Chinese Endovascular]) and a meta‐analysis have demonstrated that EVT may be associated with improved clinical outcomes for patients with acute BAO when compared with standard medical treatment. 5 , 6 , 7 , 8 In addition, our prospective BASILAR (Endovascular Treatment for Acute Basilar Artery Occlusion Study Registry) has suggested that EVT is associated with favorable outcomes in patients with BAO at 90 days and that time is critical for patients with acute BAO who receive EVT, particularly the onset‐to‐puncture time (OPT). 9 EVT has been progressively applied as a popular strategy for patients with BAO in daily clinical practice. 10 , 11 Compared with the anterior circulation, the posterior circulation has distinct anatomy and blood flow features, such as two vertebral arteries converging with the basilar artery, a highly developed, persistent collateral arterial network, reverse filling of the distal basilar artery, and delicate plasma flow around the clot. 12 As a consequence, the onset of symptoms and signs of acute BAO are complicated and can include sudden onset to maximal deficit (SOTMD), causing progressive exacerbation and fluctuations of symptoms. 1 However, the efficacy of EVT for each form of onset of BAO remains uncertain.
SOTMD is an important form of onset of acute BAO and usually presents with acute neurological deficits that peak immediately or within 5 minutes of onset without progressive exacerbation or symptom fluctuation. 1 , 13 It is associated with emboli and distal occlusions of the basilar artery, poor collateral circulation, and a large embolus load. 1 The presence of SOTMD in patients with acute BAO often results in more severe outcomes. However, no studies have yet systematically evaluated the clinical outcomes of EVT in patients with SOTMD or investigated how OPT affects the clinical outcomes of EVT.
Using data from BASILAR, the largest prospective multicentral registry, we aimed to evaluate the clinical outcomes of EVT in patients with SOTMD at 90 days and to determine how OPT affects the outcomes of EVT.
METHODS
Patient Selection
BASILAR was a nationwide, prospective registry of patients with confirmed acute symptomatic and radiological BAO, comparing medical management with EVT to medical management alone. The patients were taken from 47 comprehensive stroke centers in China between January 2014 and May 2019. Details of the study protocol have been previously published, 9 and all participating centers were required to enter patients consecutively to avoid selection bias. We performed this study according to the Strengthening the Reporting of Observational Studies in Epidemiology cohort reporting guidelines. 14 All consecutive patients with the following criteria were enrolled in the study: (1) age 18 years or older; (2) BAO confirmed by computer tomography angiography, magnetic resonance angiography, or digital subtraction angiography; (3) presenting within 24 hours of the estimated initiation of BAO; (4) intravenous thrombolysis performed within the therapeutic time window; and (5) informed consent could be obtained. EVT also had to be initiated within 24 hours of the estimated time of BAO. Patients were excluded from the study in case of: (1) evidence of intracranial hemorrhage on presentation; (2) a premorbid modified Rankin Scale (mRS) score >2; (3) a serious, advanced, or terminal illness; (4) current pregnancy or lactation; (5) lack of follow‐up information; or (6) incomplete critical baseline data (eg, imaging and time metrics). In this analysis, data from patients were consecutively included if they were treated with EVT (including medical treatment with stent retrievers or thrombus aspiration, balloon angioplasty, stenting, intra‐arterial thrombolysis, or a various combination of these approaches), and the time interval from estimated occlusion onset to arterial puncture was documented. Eligible patients presented with symptomatic, radiologically confirmed acute BAO within 24 hours of symptom onset, and intravenous thrombolysis was administered if they met the accepted local guidelines. Patients who underwent EVT in the BASILAR cohort were divided into SOTMD and non‐SOTMD (NSOTMD) groups, and SOTMD was defined as an acute neurological deficit peak immediately or within 5 minutes of onset without progressive exacerbation or fluctuation. 1 , 13 Of a total of 647 patients with BAO who underwent EVT, 270 were found to have SOTMD and 377 had NSOTMD. After recanalization of the target artery, most of the patients were transferred to the neurointensive care unit for at least 24 hours, and their systolic blood pressure was maintained at 120 to 140 mm Hg. In addition, the patients who underwent stent implantation were prescribed antithrombotic medication to prevent acute stent thrombosis. For the patients without prior intravenous alteplase, loading doses of clopidogrel (300 mg) and aspirin (300 mg) were given, or a low dose of glycoprotein IIb/IIIa inhibitor was bolus‐injected intra‐arterially and maintained for at least 24 hours. However, for those with prior intravenous alteplase, clopidogrel (75 mg) and aspirin (100 mg) were given after 24 hours of alteplase administration, and then all the patients were given clopidogrel (75 mg/d) and aspirin (100 mg/d) for 3 months. All patients underwent follow‐up at 90 days.
This study was approved by the local institutional review board of each site. Written informed consent was obtained from all patients or their legal surrogates. BASILAR was registered in the Chinese Clinical Trial Registry (http://www.chictr.org.cn; ChiCTR1800014759).
The data that support the findings of this study are available from the corresponding author upon reasonable request.
Variables and Assessment
Neurological deficits at the time of treatment were assessed using the National Institutes of Health Stroke Scale (NIHSS). The presumed causative mechanism of stroke was assessed based on the Trial of ORG 10172 in Acute Stroke Treatment (TOAST) classification. 15 In addition to the above variables, data on onset‐to‐imaging time, onset‐to‐door time, OPT, puncture‐to‐recanalization time, and type of endovascular procedure were retrieved from the BASILAR database.
Imaging Analysis
Early ischemic changes were quantified by the posterior circulation Alberta Stroke Program Early Computed Tomography Score (pc‐ASPECTS; range 0–10, with higher scores indicating smaller ischemic injury). 16 For recanalization, the modified Thrombolysis in Cerebral Infarction (mTICI) score was used; successful reperfusion was defined as a modified treatment in patients with an ischemic stroke score of 2b (50%–99% reperfusion) or 3 (complete reperfusion). Collateral circulation status was assessed using the American Society of Interventional and Therapeutic Neuroradiology/Society of Interventional Radiology (ASITN/SIR) scale, with an ASITN/SIR score of 2 to 4 indicating a favorable collateral status. 17 Correlative neuroimaging data were analyzed by a neuroimaging core laboratory, whose members (F.L. and Z.Q.) were independent, experienced neurologists who were unaware of the patients' clinical information. If the assessment was discrepant, the final decision was made by a third neurologist (W.Z.)
Outcome Measures
The primary clinical outcomes were defined as an mRS score of ≤3 (favorable outcome, indicating the ability to walk unassisted) at 90 days and mortality at the 90‐day follow‐up. The second clinical outcome was recanalization at the end of the procedure, as well as symptomatic intracranial hemorrhage within 48 hours of EVT as diagnosed by neuroimaging (computer tomography or magnetic resonance imaging). Symptomatic intracranial hemorrhage was evaluated according to the Heidelberg Bleeding Classification and was detected using brain imaging associated with any of the following conditions: an increase of ≥4 points in the NIHSS score, an increase of ≥2 points in the NIHSS score as a relevant change in neurological status, or deterioration that led to intubation/hemicraniectomy/external ventricular draining placement or other major medical intervention. 18
Statistical Analysis
All statistical analyses were performed using SPSS version 26.0 (IBM), MedCalc version 19.5.6 (MedCalc Software Ltd), and RStudio software version 1.1.463.0 (Posit Software). Statistical significance was set at P<0.05, and all P values were 2‐sided.
Normally distributed continuous variables are presented as means (SDs), while nonnormally distributed continuous variables are presented as medians (interquartile range [IQRs]). Univariate differences were analyzed using Mann–Whitney U test or Kruskal–Wallis test for numerical variables and Pearson χ2 test or Fisher exact test for categorical variables, as appropriate. The adjusted and unadjusted odds ratios (ORs) for clinical outcomes are reported with 95% CIs to indicate statistical precision, which was estimated using multivariable logistic regression. Multivariate analysis included explanatory variables (P<0.05) in the univariate analysis, adjusting for age, sex, baseline NIHSS score, occlusion sites, baseline pc‐ASPECTS, puncture‐to‐recanalization time, OPT, collateral, and cause of ischemic stroke. For propensity score matching (PSM) analysis, we performed 1:1 matching based on the nearest‐neighbor matching algorithm with a caliper width of 0.2× the propensity score, with age, baseline NIHSS, baseline pc‐ASPECTS, coronary heart disease, atrial fibrillation, collateral, stroke cause, and occlusion site included in the analysis as covariables. We adjusted for these covariables with a multifactorial analysis.
Furthermore, the predicted probabilities of binary outcomes, which were analyzed using a restricted cubic spline with 3 knots at the 10th, 50th, and 90th centiles to the flexible model, adjusting for baseline NIHSS, pc‐ASPECTS, and ASITN/SIR, were performed to create a time‐benefit curve. The differences in OPT between patients with SOTMD and NSOTMD are shown by the predicted probabilities of binary outcomes.
RESULTS
Baseline Characteristics
Of the 647 patients with acute BAO who underwent EVT (a flow diagram of patient selection is presented in Figure 1), the median age was 65 years (IQR, 57–74 years), and the baseline NIHSS score was 28 (17–34). There were 164 (25.3%) women and 483 (74.7%) men. Of all patients, 270 (41.7%) had SOTMD, and 377 (58.3%) had NSOTMD. After 1:1 PSM, a balance was achieved in the baseline characteristics between the SOTMD versus NSOTMD groups (median age, 65 years [IQR, 58.5–74.0 years] versus 65 years [IQR, 56.0–74.0 years], P=0.2; and there were 168 [75.7%] men versus 166 [74.8%] men, respectively, [P=0.8]). A comparison of the baseline characteristics of patients with SOTMD versus NSOTMD is provided in Table 1.
Figure 1. Screening flow diagram of the patients with sudden onset to maximal deficit (SOTMD) and non‐SOTMD (NSOTMD).
BAO indicates basilar artery occlusion; EVT, endovascular therapy; OTI, onset‐to‐imaging time; and SMT, standard medical treatment.
Table 1.
Baseline Patient Characteristics
| Unmatched patients, No. (%) | P value | Propensity score–matched patients, No. (%) | P value | |||||
| Total (n=647) | SOTMD (n=270) | NSOTMD (n=377) | Total (n=444) | SOTMD (n=222) | NSOTMD (n=222) | |||
| Age, median (IQR), y | 65 (57.0–74.0) | 67 (60.0–74.0) | 63 (55.0–72.0) | <0.001 | 65 (57.0–74.0) | 65 (58.5–74.0) | 65 (56.0–74.0) | 0.2 |
| Men, n (%) | 483 (74.7) | 194 (71.9) | 289 (76.7) | 0.2 | 334 (75.2) | 168 (75.7) | 166 (74.8) | 0.8 |
| Baseline NIHSS score, median (IQR) | 28 (17.0–34.0) | 28 (15.0–34.0) | 26 (17.0–32.0) | 0.3 | 28 (17.0–33.0) | 29 (16.0–34.0) | 26 (19.0–32.0) | 0.2 |
| NIHSS score >27, n (%) | 311 (48.1) | 141 (52.2) | 170 (45.1) | 0.07 | 213 (48.0) | 117 (52.7) | 96 (43.2) | 0.046 |
| Baseline pc‐ASPECTS, median (IQR)* | 8 (7.0–9.5) | 8 (7.0–10.0) | 8 (6.25–9.0) | 0.001 | 8 (7.0–9.0) | 8 (7.0–10.0) | 8 (7.0–9.0) | 0.001 |
| ASITN/SIR grade, n (%) | 0.3 | 0.9 | ||||||
| 0 to 1 | 565 (87.3) | 231 (85.6) | 334 (88.6) | 253 (57.0) | 126 (56.8) | 127 (57.2) | ||
| 2 to 4 | 82 (12.7) | 39 (14.4) | 43 (11.4) | 191 (43.0) | 96 (43.2) | 95 (42.8) | ||
| Serum glucose, median (IQR) | 7 (6.2–9.7) | 7.68 (6.01–10.02) | 7.295 (6.133–9.383) | 0.5 | 8 (6.2–9.9) | 8 (6.2–10.2) | 7 (6.2–9.6) | 0.3 |
| Systolic pressure, median (IQR), mm Hg | 150 (134.0–167.0) | 150 (130.0–165.0) | 149 (134.0–167.0) | 0.4 | 151 (134.0–165.0) | 151 (130.0–160.0) | 151 (135.0–167.0) | 0.9 |
| Diastolic pressure, median (IQR), mm Hg | 85 (76.0–97.5) | 85 (76.0–98.0) | 84 (77.0–96.0) | 0.9 | 85 (75.0–97.0) | 86 (76.0–99.0) | 84 (75.0–95.0) | 0.8 |
| Medical history, n (%) | ||||||||
| Hypertension | 451 (69.7) | 189 (70.0) | 262 (69.5) | 0.9 | 306 (68.9) | 154 (69.4) | 152 (68.5) | 0.8 |
| Hyperlipidemia | 214 (33.1) | 89 (33.0) | 125 (33.2) | 0.96 | 148 (33.3) | 75 (33.8) | 73 (32.9) | 0.8 |
| Diabetes | 149 (23.0) | 67 (24.8) | 82 (21.8) | 0.4 | 103 (23.2) | 56 (25.2) | 47 (21.2) | 0.3 |
| Ischemic stroke | 140 (21.6) | 50 (18.5) | 90 (23.9) | 0.1 | 94 (21.2) | 44 (19.8) | 50 (22.5) | 0.5 |
| Coronary heart disease | 105 (16.2) | 62 (23) | 43 (11.4) | <0.001 | 69 (15.5) | 43 (19.4) | 26 (11.7) | 0.026 |
| Atrial fibrillation | 136 (21.0) | 78 (28.9) | 58 (15.4) | <0.001 | 100 (22.5) | 50 (22.5) | 50 (22.5) | 1.000 |
| Smoking | 235 (36.3) | 83 (30.7) | 152 (40.3) | 0.012 | 161 (36.3) | 77 (34.7) | 84 (37.8) | 0.5 |
| Cause of ischemic stroke, n (%) | <0.001 | 0.9 | ||||||
| Large artery atherosclerosis | 418 (64.6) | 147 (54.4) | 271 (71.9) | 279 (62.8) | 140 (63.1) | 139 (62.6) | ||
| Cardioembolism | 173 (26.7) | 98 (36.3) | 75 (19.9) | 120 (27.0) | 61 (27.5) | 59 (19.9) | ||
| Other causes | 56 (8.7) | 25 (9.3) | 31 (8.2) | 45 (12.6) | 21 (9.3) | 24 (8.2) | ||
| Occlusion sites, n (%) | <0.001 | 1.000 | ||||||
| Distal basilar artery | 222 (34.3) | 121 (44.8) | 101 (26.8) | 170 (38.3) | 85 (38.3) | 85 (38.3) | ||
| Middle basilar artery | 195 (30.1) | 81 (30.0) | 114 (30.2) | 146 (32.9) | 73 (32.9) | 73 (32.9) | ||
| Proximal basilar artery | 107 (16.5) | 32 (11.9) | 75 (19.9) | 62 (14.0) | 31 (14.0) | 31 (14.0) | ||
| Vertebral artery‐V4 segment | 123 (19.0) | 36 (13.3) | 87 (23.1) | 66 (14.9) | 33 (14.9) | 33 (14.9) | ||
| Intravenous thrombolysis, n (%) | 119 (18.4) | 52 (19.3) | 67 (17.8) | 0.6 | 84 (18.9) | 42 (18.9) | 42 (18.9) | 1.000 |
| OTI, median (IQR), min | 210 (88.0–355.0) | 220 (100.0–337.0) | 198 (68.0–383.0) | 0.3 | 253 (155.0–394.0) | 241 (149.0–356.0) | 280 (159.0–425.0) | 0.1 |
| OTD, median (IQR), min | 215 (120.0–362.0) | 201 (110.0–317.0) | 223 (120.0–393.0) | 0.07 | 218 (120.0–356.0) | 210 (118.0–320.0) | 248 (127.0–395.0) | 0.3 |
| OPT, median (IQR), min | 328 (220.0–493.0) | 329 (219.0–475.0) | 321 (221.0.‐508.0) | 0.6 | 361 (255.0–520.0) | 351 (238.0–498.0) | 389 (279.0–590.0) | 0.7 |
| PTR, median (IQR), min | 101 (69.0–150.5) | 94.98 (66.0–140.0) | 109.19 (76.0–156.75) | 0.024 | 99 (69.0–142.0) | 99 (69.0–151.0) | 100 (71.0–140.0) | 0.6 |
| Type of endovascular procedure, n (%) | 0.1 | 0.2 | ||||||
| Stent retriever thrombectomy | 482 (74.5) | 200 (74.1) | 282 (74.8) | 338 (76.1) | 173 (77.9) | 165 (75.3) | ||
| Aspiration | 20 (3.1) | 11 (4.1) | 9 (2.4) | 11 (2.5) | 7 (4.1) | 4 (1.8) | ||
| Balloon angioplasty or stenting | 66 (10.2) | 21 (7.8) | 45 (11.9) | 47 (10.6) | 17 (7.7) | 30 (13.7) | ||
| Intra‐arterial medication or mechanical fragmentation | 75 (11.6) | 38 (14.1) | 37 (9.8) | 45 (10.1) | 25 (11.3) | 20 (9.1) | ||
ASITN/SIR indicates American Society of Interventional and Therapeutic Neuroradiology/Society of Interventional Radiology; IQR, interquartile range; NIHSS, National Institutes of Health Stroke Scale; NSOTMD, nonsudden onset to maximal deficit; OTD, onset‐to‐door time; OPT, onset‐to‐puncture time; OTI, onset‐to‐imaging time; pc‐ASPECTS, posterior circulation Alberta Stroke Program Early Computed Tomography Score; PTR, puncture‐to‐recanalization time; and SOTMD, sudden onset to maximal deficit.
Data were missing for 4 patients in the endovascular therapy cohort.
Clinical Outcomes
The clinical outcomes of patients with SOTMD and NSOTMD following EVT are presented in Table 2. In the entire patient population, there was no statistically significant difference between the SOTMD and NSOTMD groups regarding favorable outcome at 90 days (OR, 0.88 [95% CI, 0.58–1.34]). In the SOTMD group, good recanalization (mTICI score 2b/3) of the basilar artery at the end of the procedure was observed in 222 of the 270 patients (82.2%) compared with 79.6% in the NSOTMD group (OR, 1.07 [95% CI, 0.70–1.64]), and there was no statistically significant difference.
Table 2.
Clinical Outcomes of Patients With BAO by EVT
| Unmatched patients, No. (%) | Adjusted OR (95% CI) | P value | Propensity score–matched patients, No. (%) | Adjusted OR (95% CI) | P value | |||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| SOTMD | NSOTMD | Unadjusted OR (95% CI) | P value | SOTMD | NSOTMD | Unadjusted OR (95% CI) | P value | |||||
| Primary outcomes | ||||||||||||
| 90‐d mRS score 0 to 3, n (%) | 90 (33.3) | 117 (31.0) | 1.11 (0.80–1.55) | 0.5 | 0.88 (0.58–1.34) | 0.5 | 72 (32.4) | 77 (34.7) | 1.11 (0.75–1.64) | 0.6 | 1.13 (0.70–1.81) | 0.6 |
| Mortality at 90‐d, n (%) | 135 (50.0) | 164 (43.5) | 1.30 (0.95–1.78) | 0.1 | 1.67 (1.14–2.44) | 0.008 | 112 (50.5) | 85 (38.3) | 1.64 (1.13–2.40) | 0.01 | 1.92 (1.23–3.00) | 0.004 |
| Secondary outcomes | ||||||||||||
| 90‐d mRS score 0 to 2, n (%) | 75 (27.8) | 102 (27.1) | 1.04 (0.73–1.47) | 0.8 | 0.78 (0.50–1.22) | 0.3 | 58 (26.1) | 65 (29.3) | 1.17 (0.77–1.78) | 0.5 | 1.17 (0.71–1.94) | 0.5 |
| 90‐d mRS score 0 or 1, n (%) | 54 (20.0) | 80 (21.2) | 0.93 (0.63–1.37) | 0.7 | 0.70 (0.44–1.14) | 0.2 | 44 (19.8) | 52 (23.4) | 1.24 (0.79–1.95) | 0.4 | 1.24 (0.72–2.14) | 0.4 |
| Recanalization, n (%) | 222 (82.2) | 300 (79.6) | 1.19 (0.80–1.77) | 0.4 | 1.07 (0.70–1.65) | 0.8 | 183 (82.4) | 181 (81.5) | 0.94 (0.58–1.53) | 0.8 | 0.96 (0.58–1.59) | 0.9 |
| Symptomatic ICH within 48 h, n (%) | 21 (7.8) | 24 (6.4) | 1.23 (0.67–2.25) | 0.5 | 1.34 (0.69–2.57) | 0.4 | 18 (8.1) | 10 (4.5) | 1.87 (0.84–4.15) | 0.1 | 1.76 (0.77–4.02) | 0.2 |
Adjusted estimates of outcomes were calculated using binary regression, taking the following variables into account: age, sex, baseline National Institutes of Health Stroke Scale score, occlusion sites, baseline posterior circulation Alberta Stroke Program Early Computed Tomography Score (pc‐ASPECTS), coronary heart disease, puncture to recanalization time, and cause of ischemic stroke. BAO indicates basilar artery occlusion; EVT, endovascular therapy; ICH, intracranial hemorrhage; mRS, modified Rankin Scale score; NSOTMD, nonsudden onset to maximal deficit; OR, odds ratio; and SOTMD, sudden onset to maximal deficit.
However, the SOTMD group had a significantly higher mortality rate at 90 days than the NSOTMD group (50.0% versus 43.5%, respectively; P=0.008), with an adjusted OR of 1.67 (95% CI, 1.14–2.44). Figure 2 also illustrates the 90‐day mRS distribution between the SOTMD and NSOTMD cohorts. The proportion of symptomatic intracerebral hemorrhage was 7.8% in the SOTMD subgroups and 6.4% in the NSOTMD subgroups (P=0.5). Moreover, after 1:1 PSM analysis, the results were consistent with the multivariable regression logistic analysis with adjustment for covariates and are presented in Table 2.
Figure 2. Distribution of the modified Rankin scale score at 90 days in patients with sudden onset to maximal deficit (SOTMD) and non‐SOTMD (NSOTMD) by endovascular therapy.
Restricted Cubic Spline Analysis for the Association Between Continuous OPT and Outcomes in Patients With SOTMD and NSOTMD
The continuous time‐benefit curve showed that the probability of achieving a 90‐day favorable outcome of patients with SOTMD declined from 32.0% to 20.0% within 6 hours and then leveled off, although the difference was not statistically significant (adjusted P for nonlinearity=0.28, adjusted P for linear trend=0.55) (Figure 3A). In the NSOTMD cohort, the probability of a favorable outcome declined from 38.0% at 1 hour to 18.0% at 8 hours, and the difference was statistically significant (adjusted P for nonlinearity=0.04) (Figure 3C). In terms of safety, the probability of 90‐day mortality increased from 40.0% at 1 hour to 70.0% at 6 hours in the SOTMD cohort, and the difference was statistically significant (adjusted P for nonlinearity=0.03) (Figure 3B). In contrast, in the NSOTMD cohort, the probability of mortality at 90 days increased from 38.0% at 1 hour to 48.0% at 8 hours and then leveled off, although the difference was not statistically significant (adjusted P for nonlinearity=0.41, adjusted P for linear trend=0.52) (Figure 3D).
Figure 3. Changes in the predicted probability of outcomes with continuous variation in onset‐to‐puncture time (OPT).
Each graph shows the predicted probability (solid line) and 95% CI (graph shade) of different outcomes: favorable outcome (modified Rankin Scale [mRS] 0–3) in patients with sudden onset to maximal deficit (SOTMD) (A), mortality in patients with SOTMD (B), favorable outcome (mRS 0–3) in patients with non‐SOTMD (NSOTMD) (C), and mortality in the patients with NSOTMD (D). The predicted probabilities for each value of the OPT were computed by setting all other variables in the model to the mean values. The associations of treatment time with mRS 0 to 3 and mortality in patients with SOTMD and the associations of treatment time with mRS 0 to 3 and mortality in the patients with NSOTMD were modeled as 2 different linear relations.
Factors Associated With 90‐Day Favorable Outcome With EVT in Patients With SOTMD
In the binary logistic analysis, baseline NIHSS score, baseline pc‐ASPECTS, collateral status, diabetes, and recanalization were independent predictors of favorable outcome (Table 3). In the SOTMD group, we found that a baseline NIHSS score >27 was associated with a 3‐fold increase in the risk of poor outcome, and a baseline pc‐ASPECTS >7 was associated with a 4‐fold increase in positive prognosis. In addition, recanalization and improved collateral circulation were associated with 5‐fold and 2‐fold increases in favorable outcomes, respectively. Patients with SOTMD and diabetes were twice as likely to have a poor prognosis compared with those without diabetes.
Table 3.
Multivariate Analysis: Predictors of Favorable Outcome in Patients With SOTMD With EVT
| OR | 95% CI | P value | |
|---|---|---|---|
| Age | 0.99 | 0.97–1.01 | 0.2 |
| Baseline NIHSS score | |||
| 0 to 27* | |||
| >27 | 0.29 | 0.19–0.44 | <0.001 |
| Baseline pc‐ASPECTS | |||
| 0 to 7* | |||
| >7 | 3.83 | 2.45–5.99 | <0.001 |
| Diabetes | 0.55 | 0.33–0.92 | 0.022 |
| Sex | 0.65 | 0.41–1.03 | 0.06 |
| Recanalization | 4.82 | 2.48–9.37 | <0.001 |
| ASITN/SIR grade (2 to 4) | 1.70 | 1.36–2.14 | <0.001 |
| Coronary heart disease | 0.80 | 0.44–1.43 | 0.5 |
| OPT | 1.00 | 0.99–1.00 | 0.3 |
ASITN/SIR indicates American Society of Interventional and Therapeutic Neuroradiology/Society of Interventional Radiology; NIHSS, National Institutes of Health Stroke Scale; OPT, onset‐to‐puncture time; OR, odds ratio; pc‐ASPECTS, posterior circulation Alberta Stroke Program Early Computed Tomography Score; and SOTMD, sudden onset to maximal deficit.
Data were missing for 4 patients in the endovascular therapy (EVT) cohort.
Predictors of 90‐Day Mortality in Patients With SOTMD With EVT
After adjusting for age, baseline NIHSS score, baseline pc‐ASPECTS, OPT, recanalization, collateral status, intravenous thrombolysis, diabetes, and atrial fibrillation, we found that age, baseline NIHSS score, baseline pc‐ASPECTS, diabetes, recanalization, and collateral status were predictors of 90‐day mortality in the binary logistic regression analysis (Table 4). A baseline NIHSS score >27 and baseline pc‐ASPECTS <7 were associated with a 3‐fold increase and 2‐fold increase in mortality, respectively. Recanalization was associated with a 7‐fold reduction in mortality, while better collateral circulation was associated with a 2‐fold reduction. Patients with SOTMD and diabetes had a mortality risk twice as high as that of patients with SOTMD without diabetes.
Table 4.
Multivariate Analysis: Predictors of Mortality in SOTMD Patients With EVT
| OR | 95% CI | P value | |
|---|---|---|---|
| Age | 1.02 | 1.01–1.04 | 0.009 |
| Baseline NIHSS score | |||
| 0 to 27* | |||
| >27 | 3.08 | 2.08–4.58 | <0.001 |
| Baseline pc‐ASPECTS | |||
| 0 to 7* | |||
| >7 | 0.42 | 0.29–0.62 | <0.001 |
| Recanalization | 0.14 | 0.08–0.24 | <0.001 |
| ASITN/SIR grade (2 to 4) | 0.58 | 0.46–0.72 | <0.001 |
| Intravenous thrombolysis | 0.73 | 0.45–1.19 | 0.2 |
| Diabetes | 1.89 | 1.23–2.96 | 0.005 |
| Atrial fibrillation | 0.76 | 0.46–1.23 | 0.3 |
| OPT | 1.00 | 1.00–1.001 | 0.6 |
ASITN/SIR indicates American Society of Interventional and Therapeutic Neuroradiology/Society of Interventional Radiology; NIHSS, National Institutes of Health Stroke Scale; OPT, onset‐to‐puncture time; OR, odds ratio; pc‐ASPECTS, posterior circulation Alberta Stroke Program Early Computed Tomography Score; and SOTMD, sudden onset to maximal deficit.
Data were missing for 4 patients in the endovascular therapy (EVT) cohort.
DISCUSSION
This retrospective analysis of prospectively collected data from BASILAR investigated real‐world clinical experiences to evaluate the outcomes associated with EVT in patients with BAO. Our study found that no significant difference was observed in favorable outcomes between the SOTMD and NSOTMD groups, although the mortality of patients with SOTMD was higher than that of patients with NSOTMD. In addition, the patients with SOTMD had stronger time dependence for EVT in terms of mortality, while the time dependency regarding favorable outcome in the NSOTMD group was even higher.
Due to the distinct anatomy and blood flow features of the posterior circulation, the onset of signs and symptoms of acute BAO are varied. 12 Previous studies have demonstrated that the presence of a prodromal minor stroke at admission can predict the risk of poor outcome at 1 month in patients with acute symptomatic BAO. 1 , 19 However, no studies, to our knowledge, have systematically evaluated the clinical outcomes of EVT in patients with SOTMD. It is interesting to note that in our study, the favorable outcome rate was similar between patients with SOTMD and NSOTMD after EVT (33.3% versus 31.0%, respectively; OR, 0.88 [95% CI, 0.58–1.34]), and the recanalization rate also did not differ between the 2 groups. Moreover, regarding the 90‐day mRS score, our study shows that the favorable outcomes (mRS 0–3) in patients with SOTMD who underwent EVT were better than those of patients with acute BAO who received medical treatment (33.3% versus. 9.3%, respectively). 9 In addition, in our study, the ASITN/SIR grade of collaterals in the 2 groups was not different (P=0.3), and there were also no differences in the cause of ischemic stroke after 1:1 PSM analysis. Moreover, a previous study showed that there was no difference in the 90‐day or long‐term functional outcomes (mRS 0–2) of patients undergoing EVT who had BAOs associated with intracranial artery atherosclerosis or embolism. 20 In addition, the posttreatment care of the patients in the 2 groups was consistent. Therefore, all of these results suggest that patients with SOTMD could benefit from EVT. However, in our study, patients with SOTMD and EVT had a higher mortality rate (adjusted OR, 1.67 [95% CI, 1.14–2.44]; P=0.008). There is growing evidence that higher baseline NIHSS scores were associated with poor outcomes and high mortality. 21 , 22 In our study, after PSM analysis, the proportion of patients with NIHSS scores >27 was much higher in the SOTMD group (P=0.046), suggesting that these patients had more severe symptoms at onset, which could be associated with higher mortality. In addition, the following factors may also account for the increased mortality observed in patients with SOTMD compared with those with NSOTMD. First, patients with SOTMD were generally older than those with NSOTMD. Previous studies have demonstrated that older patients who undergo EVT have higher overall mortality rates than younger patients. 22 Second, there was a higher proportion of patients with coronary heart disease in the SOTMD group than in the NSOTMD group, which could contribute to the increased mortality rate observed in the former. 23 In summary, the application of EVT is a beneficial treatment approach for patients with BAO in SOTMD, despite the higher mortality rate.
For ischemic stroke, in current clinical practice, time to EVT is strongly associated with functional outcome in anterior circulation, 24 , 25 and earlier EVT has been associated with improved outcome in patients with acute BAO. 26 Similar results are presented in this study. Moreover, we also found that the clinical outcomes affected by OPT were different between the SOTMD and NSOTMD groups with EVT. In our study, the time‐benefit curve of the relationship between mRS 0 to 3 and OPT declined gradually before 6 hours (from 32.0% at 1 hour to 20.0% at 6 hours) (Figure 3A) and then leveled off in the SOTMD cohort. A consistent trend toward better outcomes was observed when earlier treatment was provided within 6 hours, although the differences were not found to be statistically significant. Despite this, OPT was associated with improved outcomes after EVT was performed within 8 hours following symptom onset in the NSOTMD cohort. After this, the odds of benefit transitioned to a relative plateau (from 38.0% at 1 hour to 18.0% at 8 hours, adjusted P for nonlinearity=0.04) (Figure 3C). In terms of safety outcomes, there was a significant increase in mortality within 6 hours following symptom onset in the SOTMD group (from 40.0% at 1 hour to 70.0% at 6 hours, adjusted P for nonlinearity=0.03) (Figure 3B). In contrast, there was a consistent trend toward increased mortality with earlier treatment within 8 hours in the NSOTMD cohort (from 38.0% at 1 hour to 48.0% at 8 hours) (Figure 3D). The above results suggest that there is significant time dependence for EVT regarding the 90‐day clinical outcomes of patients with SOTMD and NSOTMD, suggesting that the earlier the treatment, the better the outcomes. Restrictive cubic spline analysis demonstrated that early EVT within 6 hours after onset may be associated with lower mortality rates in the SOTMD group and suggested that the optimal treatment time window is 6 hours from onset to puncture. For patients with NSOTMD, early EVT within 8 hours is significantly correlated with a good prognosis. It is suggested that the optimal treatment time window for EVT is within 8 hours of onset. These results are consistent with previous studies reporting that patients with acute BAO should receive EVT as soon as possible. 26 Therefore, the patients with SOTMD had stronger time dependence for EVT in terms of mortality, while the time dependency of favorable outcome in the NSOTMD group was even higher. Our study further explored the time dependence of patients with different onset modes, including the optimal time window and target outcome. However, after 8 hours, there still seemed to be a relevant benefit for EVT in the NSOTMD group, suggesting that the strict time dependency for patients with BAO seems less critical than in the anterior circulation, which may be associated with the distinct anatomy and blood flow features of the posterior circulation. These results are consistent with previous research and German Stroke Registry analysis. 27 , 28 Despite all of this, we believe that the 6‐hour or 8‐hour time point after symptom onset could still provide a reference framework for interventionists to treat patients with BAO. In addition, performing EVT as soon as possible in all patients with BAO is desirable in clinical practice.
The results of our study also show that baseline NIHSS score, baseline pc‐ASPECTS, diabetes, recanalization, and ASITN/SIR grade are independent predictors of favorable outcome and mortality in the SOTMD patient cohort. A baseline NIHSS score >27 and pc‐ASPECTS <7 were associated with a poor prognosis. Age was also an independent predictor of mortality. Our results are consistent with the conclusions of previous studies, which demonstrated that a higher NIHSS score, pc‐ASPECTS <7, diabetes, and poor collateral status are common risk factors for patients with BAO. 20 , 22 , 29
Our study has several limitations. First, it is affected by all of the inherent limitations of a nonrandomized study. The selection of consecutive patients with EVT from the database may have resulted in selection bias; however, this was accounted for by the application of PSM. Second, patients were dichotomized based on the onset of symptoms and signs of acute BAO rather than the TOAST classification, which was likely to lead to some confounders. However, in the context of emergency treatment, this classification method is simple and practical, and there was no difference in the functional outcomes of patients undergoing EVT who had BAO associated with intracranial artery atherosclerosis or embolism. 20 In addition, confounding factors were not fully controlled for between the two cohorts, eg, prestroke mRS, which may have potentially influenced our results. Finally, in the time‐benefit curve analysis, confounding factors were not fully controlled for between the two cohorts, which might have potentially influenced our results. Despite these limitations, the results from our study could still remind clinical doctors to implement EVT within 6 hours for patients with BAO who have SOTMD, and our results could help predict clinical prognosis.
In conclusion, no significant difference was observed in favorable outcomes between patients with SOTMD and those with NSOTMD, although the mortality of patients with SOTMD was higher than that of patients with NSOTMD. Moreover, the patients with SOTMD had stronger time dependence for EVT in terms of mortality, while the time dependency for favorable outcome in the NSOTMD group was even higher.
Sources of Funding
This study was funded by the Incubation Project of Weihai Municipal Hospital affiliated with Shandong University and the Medical and Health Project of Wuhan Health commission, Incubation Project of Weihai Municipal Hospital affiliated with Shandong University: FH‐2021‐XY01, and Medical and Health Project of Wuhan Health commission: WX21C09.
Disclosures
The authors declare that they have no conflict of interest.
Acknowledgments
We would like to thank all of the coinvestigators for their dedication to the study. No compensation was received from a funding sponsor for such contributions.
This article was sent to Luciano A. Sposato, MD, MBA, Associate Editor, for review by expert referees, editorial decision, and final disposition.
For Sources of Funding and Disclosures, see page 11.
Editorial by Abdalkader and Nguyen.
Contributor Information
Yue Wan, Email: wylydia@aliyun.com.
Pengfei Wang, Email: wpf5287598@163.com.
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