A total of 84 patients with acute ischemic stroke participated in this study from March 2018 to September 2019 at Harbin Medical University’s Second Affiliated Hospital. Each enrolled patient was tended using SOLITAIRE FR (Medtronic, USA) for EVT. There were 32 patients in the favorable clinical outcomes group and 52 patients in the unfavorable clinical outcomes group. Table 1 presents the collected data of all enrolled patients.
Clinical data and laboratory test were assessed with univariable analysis and presented in Table 2. No difference was observed among patients treated by mechanical thrombectomy and rescue therapy, no difference was observed on considering age (62 years vs 65 years, p = 0.086), male (65.63 % vs 76.92 %, p = 0.259) and smoking (59.38 % vs 51.92 %, p = 0.505). There was also no variation in medical history of patients, including hypertension (53.13 % vs 59.62 %, p = 0.559), DM (21.88 % vs 23.08 % , p = 0.898), AF (28.13 % vs 23.08 %, p = 0.604), CAD (15.63 % vs 21.15 %, p = 0.531), history of ischemic stroke (15.63 % vs 15.38 %, p = 1.000). Endovascular treatment and its pre-procedure assessment were also non-significant between both groups in terms of admission NIHSS (14 vs 14, p = 0.933), ASPECTS (9 vs 8, p = 0.622) and OTP (243.5 min vs 261.5 min, p = 0.484). Here, a few patients received EVT beyond the window of standard time, being 6 hours of onset of symptoms, and these patients met eligibility criteria DEFUSE 3 or DAWN [8, 9]. We thus assessed this group of patients according to beyond time window, and this also showed insignificant effect on prognosis of acute ischemic stroke (18.75 % vs 23.08 %, p = 0.639). Insignificant difference was seen among favorable and unfavorable clinical outcomes in patients treated by IVT prior to EVT (31.25 % vs 26.92 %, p = 0.639). The primary judgement based on MRA or CTA and confirmed finally from DSA, in both groups the occlusion sites mainly contained the ICA (25.00 % vs 32.69 %), MCA (53.13 % vs 30.77 %), and BA (12.50 % vs 25.00 %). The occlusion sites between patients were not of significance (p = 0.110), and tandem occlusion was not significant (9.38 % vs 11.54 %, p = 1.000). GTR showed significant difference on prognosis of acute ischemic stroke (45.0 min vs 72.5 min, p = 0.001). A significant difference was observed in few laboratory tests between both groups, such as serum iron (10.87 μmol/L vs 4.07 μmol/L, p < 0.001), TT (13.40 s vs 14.25 s, p = 0.034], but serum calcium (2.24 μmol/L vs 2.21 μmol/L, p = 0.522), PT (10.95 s vs 10.90 s, p = 0.593), PTA (93.00 % vs 93.50 %, p = 0.423), PTR (1.02 vs 1.01, p = 0.605), INR (1.02 vs 1.01, p = 0.596), APTT (31.95 s vs 31.65 s, p = 0.728), FIB (3.12g/L vs 2.86 g/L, p = 0.064), D-dimer (223.00 ng/L vs 216.50 ng/L, p = 0.343) showed no difference.
In multivariate binary logistic regression analysis, each factor was analyzed after univariate analysis and exhibiting a potential association was mentioned in Table 3. Serum iron (p < 0.001, adjusted OR: 70.765, 95 % CI: 9.904 - 505.636) was independently associated with favorable clinical outcomes instead of age (p = 0.070, adjusted OR: 0.238, 95 % CI: 0.050 - 1.126), GTR (p = 0.082, adjusted OR: 0.270, 95 % CI: 0.062 - 1.182), FIB (p = 0.131, adjusted OR: 0.314, 95 % CI: 0.070 - 1.410) and TT (p = 0.168, adjusted OR: 0.336, 95 % CI: 0.071 - 1.584).
Sex difference and blood collection time directly influence serum iron levels in congruence with previous reports [13, 14]. In this study, we respectively divided all patients into two subgroups based on sex difference and iron in blood collection. The results showed that serum iron was still significantly associated with favorable clinical outcomes in male subgroup (11.18 μmol/L vs 4.67 μmol/L, p < 0.001) (Figure 1A) as well as in female subgroup (8.93 μmol/L vs 3.97 μmol/L, p < 0.001) (Figure 1B). We divided those patients based on blood collection time into 8:00 am to 15:00 pm and 15:00 pm to 8:00 am the next day, and we found that serum iron was also significantly associated with favorable clinical outcomes in 8:00 am to 15:00 pm (10.83μmol/L vs 5.21 μmol/L, p< 0.001) (Figure 1C ) and 15:00 pm to 8:00 am (10.91 μmol/L vs 3.97 μmol/L, p < 0.001) (Figure 1D). This suggested that serum iron was not affected by sex difference and blood collection iron in the aspect of predicting acute ischemic stroke prognosis.
As an index to prognosis of the outcome, the serum iron level optimal cutoff value was projected based on the ROC curve to be 6.86 μmol/L, with 96.9 % sensitivity and 71.2 % specificity, and AUC of 0.926 (p < 0.001, 95 % CI: 0.872 - 0.979). serum iron showed a significantly accurate ability for prognosis of acute ischemic stroke by EVT.