Of the enrolled patients, 143/245 with AIS were treated through EVT from April 2016 to April 2019 based on the inclusion and exclusion criterion, including 69 patients treated by single attempt of stent retrieval and 74 patients treated by multiple attempts (Fig. 1). All patients were treated with second generation stent retrievers, including Solitaire (Medtronic, Irvine, CA, USA). Clinical data and laboratory data in all enrolled patients were shown in Table 1. Notably, all patients with intravenous thrombolysis prior to EVT were treated with tissue-type plasminogen activator (t-PA).
Table 1
Characteristics of All Enrolled Patients
| All patients(n = 143) |
Baseline Characteristics | |
Age, median (IQR) | 62(56–69) |
Male sex, n (%) | 105(73.4%) |
Hypertension, n (%) | 86(60.1%) |
Diabetes Mellitus, n (%) | 30(21.0%) |
Atrial Fibrillation, n (%) | 44(30.8%) |
History of ischemic stroke, n (%) | 29(20.3%) |
Smoking, n (%) | 56(39.2%) |
NIHSS score, median (IQR) | 14(11–18) |
ASPECTS, median (IQR) | 8(8–10) |
OTP (min), median (IQR) | 264(197–355) |
EVT beyond time window | 32(22.4%) |
IVT, n (%) | 34(23.8%) |
Occlusion sites, n (%) | |
ICA | 25(17.5%) |
M1 | 64(44.8%) |
M2 | 5(3.5%) |
BA | 28(19.6%) |
Distal Occlusion in Tandem Occlusion | 21(14.7%) |
Stroke cause, n (%) | |
LAA | 72(50.3%) |
Cardioembolic | 44(30.8%) |
Others | 27(18.9%) |
Baseline measurement in laboratory test | |
Leukocyte level*109/L, median (IQR) | 9.40(7.65–11.8) |
Neutrophil level*109/L, median (IQR) | 7.35(5.50–9.92) |
Lymphocyte level*109/L, median (IQR) | 1.45(1.02–1.90) |
NLR, median (IQR) | 5.67(2.97–8.49) |
Serum glucose(mmol/L), median (IQR) | 7.36(6.00-10.02) |
Complications | |
ICH | 38(26.6%) |
sICH | 21(14.7%) |
others | 5(3.5%) |
Clinical Outcomes | |
Favorable clinical outcomes, n (%) | 48(33.6%) |
Mortality, n (%) | 34(23.8%) |
Table 2 showed clinical outcomes and incidence of complications following univariable and multivariable analysis. More patients with the favorable clinical outcome (mRS 0–2) were treated through single attempt of stent retrieval than those through multiple attempts (p = 0.02). Patients treated through single attempt of stent retrieval showed as lower incidence of ICH (p = 0.005) and sICH (p = 0.001) compared to the multiple attempts group. The mortality (p = 0.181) and the incidence of other complications (p = 0.406), including reocclusion, distal embolization or ischemic refusion damage, did not differ between single and multiple attempts of stent retrieval. Table 2 also showed that single attempt of stent retrieval was not independently related to the incidence of ICH (p = 0.876; adjusted OR [95%CI]: 0.914 [0.294–2.843] ), but was independently related to the incidence of sICH (p = 0.046; adjusted OR [95%CI]: 0.192 [0.038–0.973] ). The favorable clinical outcomes were independently associated with single attempt of stent retrieval (p = 0.016; adjusted OR [95%CI]: 2.652 [1.204–5.843] ). This suggested that single attempt of stent retrieval could decrease the incidence of sICH and improve favorable clinical outcomes compared with multiple attempts.
Table 2
Single Attempt of Stent Retrieval for Complications and Prognosis of Acute Ischemic Stroke
| Univariable Analysis | Multivariable Analysis |
| Single attempt (n = 69) | Multiple attempts(n = 74) | P value | P value | Adjusted OR | 95%CI |
Complications | | | | | | |
ICH | 11(15.9%) | 27(36.5%) | 0.005 | 0,876 | 0.914 | 0.294–2.843 |
sICH | 3(4.3%) | 18(24.3%) | 0.001 | 0.046 | 0.192 | 0.038–0.973 |
others | 1(1.4%) | 4(5.4%) | 0.406 | / | / | / |
Clinical Outcomes | | | | | | |
Favorable clinical outcomes, n (%) | 32(46.4%) | 16(21.6%) | 0.002 | 0.016 | 2.652 | 1.204–5.843 |
Mortality, n (%) | 13(18.8%) | 21(28.4%) | 0.181 | / | / | / |
To further analyze the factors associated with single attempt of stent retrieval, the detailed characteristics of the patients were assessed in Table 3. There were no significance differences between single and multiple attempts of stent retrieval upon the analysis of most factors through univariable analysis including age (p = 0.400), male (p = 0.100), hypertension (p = 0.124), atrial fibrillation (p = 0.419), a history of ischemic stroke (p = 0.404), smoking (p = 0.726), NHISS scores (p = 0.968), ASPECTS (p = 0.270), symptom onset to groin puncture time (p = 0.182), endovascular treatment beyond the time window (p = 0.563), intravenous thrombolysis (IVT) (p = 0.873), occlusion sites (p = 0.154), distal occlusion in tandem occlusion (p = 0.377), stroke causes (p = 0.692), leukocyte levels (p = 0.374), neutrophil levels (p = 0.222), lymphocyte levels (p = 0.864), neutrophil to lymphocyte ratio (NLR) (p = 0.241) and blood glucose levels (p = 0.076). Only diabetes mellitus showed significant differences between single and multiple attempts of stent retrieval (p = 0.023). Table 3 shows the multivariable analysis of the independent factors for single attempt of stent retrieval and its associated factors (p < 0.1). Blood glucose levels were not independent an independent factor related to single attempt of stent retrieval (p = 0.135; adjusted OR [95%CI]: 1.745 [0.841–3.620] ), whilst single attempt was associated with diabetes mellitus (p = 0.026; adjusted OR [95%CI]:2.871 [1.137–7.249] ). However, blood glucose levels only differed in those with or without diabetes mellitus, which may influence the data. We therefore divided patients into those with diabetes mellitus and those without diabetes mellitus and further analyzed the relationship between blood glucose levels and stent retrieval. Figure 2A showed no significant differences in blood glucose levels between single and multiple attempts of stent retrieval in patients with diabetes mellitus (11.29 [10.37–14.22] versus 11.0 [8.42–12.66], p = 0.221). Figure 2B also showed a non-significant difference in patients without diabetes mellitus (6.53 [5.89–8.20] versus 6.77 [5.72–8.23], p = 0.662). Subgroup analysis suggested that blood glucose levels were not related to single attempt of stent retrieval, and that only diabetes mellitus represent an independent factor for single attempt.
Table 3
Univariable Analysis and Multivariable Analysis on Single Attempt and Multiple Attempts of Stent Retrieval
| Univariable Analysis | Multivariable Analysis |
| Single attempt (n = 69) | Multiple attempts(n = 74) | P value | P value | Adjusted OR | 95%CI |
Baseline Characteristics | | | | | | |
Age, median (IQR) | 62(56–67) | 64(56–71) | 0.4 | / | / | / |
Male sex, n (%) | 55(79.7%) | 50(67.6%) | 0.1 | / | / | / |
Hypertension, n (%) | 46(66.7%) | 40(54.1%) | 0.124 | / | / | / |
DM, n (%) | 20(29.0%) | 10(13.5%) | 0.023 | 0.026 | 2.871 | 1.137–7.249 |
AF, n (%) | 19(27.5%) | 25(33.8%) | 0.419 | / | / | / |
History of ischemic stroke, n (%) | 16(23.2%) | 13(17.6%) | 0.404 | / | / | / |
Smoking, n (%) | 26(37.7%) | 30(40.5%) | 0.726 | / | / | / |
NIHSS score, median (IQR) | 14(11–18) | 14(11–17) | 0.968 | / | / | / |
ASPECTS, median (IQR) | 9(8–10) | 8(7–10) | 0.27 | / | / | / |
OTP (min), median (IQR) | 254(178–350) | 275(216–360) | 0.182 | / | / | / |
EVT beyond time window | 14(20.3%) | 18(24.3%) | 0.563 | / | / | / |
IVT, n (%) | 16(23.2%) | 18(24.3%) | 0.873 | / | / | / |
Occlusion sites, n (%) | | | 0.154 | / | / | / |
ICA | 7(10.1%) | 18(24.3%) | | | | |
M1 | 32(46.4%) | 32(43.2%) | | | | |
M2 | 2(2.9%) | 3(4.1%) | | | | |
BA | 16(23.2%) | 12(16.2%) | | | | |
Distal Occlusion in Tandem Occlusion | 12(17.4%) | 9(12.2%) | 0.377 | / | / | / |
Stroke cause, n (%) | | | 0.692 | / | / | / |
LAA | 37(53.6%) | 35(47.3%) | | | | |
Cardioembolic | 19(27.5%) | 25(33.8%) | | | | |
Others | 13(18.8%) | 14(18.9%) | | | | |
Baseline measurement in laboratory test | | | | / | / | / |
Leukocyte level*109/L, median (IQR) | 9.20(7.50–11.60) | 9.60(7.83-12) | 0.374 | / | / | / |
Neutrophil level*109/L, median (IQR) | 6.90(5.38–9.74) | 7.54(5.61–10.36) | 0.222 | / | / | / |
Lymphocyte level*109/L, median (IQR) | 1.43(1.01–1.98) | 1.48(1.02–1.86) | 0.864 | / | / | / |
NLR, median (IQR) | 4.79(2.67–8.40) | 5.98(3.41–8.87) | 0.241 | / | / | / |
Serum glucose(mmol/L), median (IQR) | 7.69(6.04–10.52) | 6.89(5.79–8.95) | 0.076 | 0.135 | 1.745 | 0.841–3.620 |