The Impact of Early Postoperative Blood Pressure Variability and Hypertension Status on 90‐Day Functional Outcomes in Acute Ischemic Stroke due to Large Vessel Occlusion Patients Treated With Mechanical Thrombectomy

ABSTRACT

Objectives

To investigate the impact of early postoperative blood pressure variability (BPV) on 90‐day functional outcomes in patients with acute ischemic stroke due to large vessel occlusion (AIS‐LVO) undergoing mechanical thrombectomy, and to assess its interaction with pre‐existing hypertension.

Methods

This retrospective cohort study included 144 AIS‐LVO patients treated with mechanical thrombectomy between January 2022 and September 2024. Systolic blood pressure was recorded hourly during the first 24 h post‐procedure, and BPV was calculated as the standard deviation of systolic BP. Patients were divided into low and high BPV groups according to the median BPV value. Functional outcome at 90 days was assessed using the modified Rankin Scale (mRS), with 0–2 defined as favorable. Subgroup analyses were performed according to hypertension status.

Results

Patients in the high BPV group had significantly higher baseline NIHSS and worse 90‐day mRS scores (p = 0.021 and p = 0.007, respectively). Favorable outcomes were achieved in 29.5% of high BPV patients compared with 60% of low BPV patients (p = 0.007). ROC analysis showed moderate predictive ability of BPV for favorable outcomes (AUC = 0.743, 95% CI: 0.662–0.840). The detrimental effect of elevated BPV was more pronounced among patients with pre‐existing hypertension.

Conclusions

Elevated early postoperative BPV is independently associated with worse 90‐day functional outcomes in AIS‐LVO patients undergoing thrombectomy, particularly in those with hypertension. These findings suggest that maintaining stable blood pressure during the early postoperative period may help optimize recovery in this high‐risk population.

Early postoperative blood pressure variability independently predicts poor 90‐day functional outcomes in AIS‐LVO patients after mechanical thrombectomy, with the adverse effect amplified in those with pre‐existing hypertension. Maintaining stable blood pressure in the early postoperative period may improve recovery in this high‐risk population

1. Introduction

Acute ischemic stroke due to large vessel occlusion (AIS‐LVO) is a leading cause of mortality and long‐term disability worldwide. Mechanical thrombectomy has significantly improved outcomes in patients with AIS‐LVO by rapidly restoring cerebral blood flow [1]. However, despite successful recanalization, many patients continue to experience poor neurological recovery, indicating the need for optimized perioperative management strategies.

Blood pressure (BP) management in the early postoperative period after thrombectomy is a critical aspect of stroke care. Both absolute BP levels and blood pressure variability (BPV) have been identified as important factors influencing functional outcomes [2]. While prior studies have established the association between high BPV and poor outcomes in ischemic stroke, most have focused on general stroke populations or used broader windows of BP monitoring. Limited data are available regarding the impact of early postoperative BPV within the first 24 h after mechanical thrombectomy, a period that may be particularly vulnerable due to impaired cerebral autoregulation and reperfusion injury.

Recent trials, such as the ENCHANTED2/MT study, have highlighted the complex relationship between BP management and functional outcomes in patients undergoing endovascular therapy [3]. These findings suggest that not only absolute BP targets but also BP stability play a crucial role in determining long‐term recovery. However, the interaction between early postoperative BPV and pre‐existing hypertension status—a common comorbidity in stroke patients—has not been well explored.

Therefore, the aim of this study was to evaluate the relationship between early postoperative BPV and 90‐day functional outcomes in patients with AIS‐LVO treated with mechanical thrombectomy. Additionally, we sought to assess whether the presence of pre‐existing hypertension modified the impact of BPV on outcomes. We hypothesized that elevated early BPV would be associated with worse neurological recovery, particularly in patients with hypertension, underscoring the importance of individualized BP management in this high‐risk population.

2. Materials and Methods

2.1. Study Design and Population

This retrospective observational study included 144 patients with large vessel occlusion acute ischemic stroke (AIS‐LVO) who underwent mechanical thrombectomy between January 2022 and September 2024 in a single stroke center in Beijing, China. Patients were consecutively enrolled. Inclusion criteria were: (1) diagnosis of AIS‐LVO confirmed by neuroimaging, (2) age ≥ 18 years, (3) successful recanalization achieved by mechanical thrombectomy, and (4) availability of postoperative blood pressure data within the first 24 h. Exclusion criteria included: (1) incomplete clinical or blood pressure data, (2) loss to follow‐up at 90 days, (3) pre‐stroke mRS score ≥ 3, and (4) serious comorbid conditions such as advanced cancer or severe organ dysfunction (Figure 1). This study was conducted in accordance with the Declaration of Helsinki (as revised in 2024). Informed consent was waived due to the retrospective design. All patient data were de‐identified prior to analysis. This study was approved by the Ethics Committee of Beijing Chao‐Yang Hospital, Capital Medical University (Approval No. 2022‐KE‐268). The reporting of this study conforms to the STROBE guidelines [4].

FIGURE 1.

Workflow of the study.

2.2. Data Collection

Demographic and clinical data were collected from electronic medical records, including age, sex, history of hypertension, diabetes, smoking status, and preoperative National Institutes of Health Stroke Scale (NIHSS) scores. The 90‐day functional outcome was assessed using the modified Rankin Scale (mRS), with mRS 0–2 defined as a favorable outcome and mRS 3–6 as an unfavorable outcome.

2.3. Blood Pressure Variability (BPV) Measurement

Postoperative blood pressure measurements were obtained at 1‐h intervals within the first 24 h after thrombectomy using automated noninvasive monitors. Blood pressure variability (BPV) was calculated as the standard deviation (SD) of systolic blood pressure measurements within this period.

2.4. Grouping and Subgroup Analysis

Based on the median postoperative systolic BPV value of 14 mmHg, patients were categorized into a low BPV group (< 14 mmHg, n = 100) and a high BPV group (≥ 14 mmHg, n = 44). This threshold was chosen given the absence of a universally accepted cutoff in prior literature, and it falls within the range of BPV values (12–16 mmHg) commonly reported in ischemic stroke studies [5, 6]. Additionally, subgroup analyses were conducted based on hypertension status (defined as a prior diagnosis of hypertension before stroke onset). Because most patients were admitted for emergency thrombectomy, detailed information on pre‐stroke blood pressure control or antihypertensive treatment was not consistently available; therefore, hypertension status was classified only by prior diagnosis.

2.5. Statistical Analysis

Statistical analyses were performed using GraphPad Prism version 10.0 (GraphPad Software, San Diego, CA, USA). Continuous variables were expressed as mean ± standard deviation (SD) and compared using independent samples t‐tests or Mann–Whitney U tests, as appropriate. Categorical variables were compared using chi‐square tests. Multivariable logistic regression analysis was performed to identify independent predictors of a favorable 90‐day outcome (mRS ≤ 2). Covariates included age, sex, baseline NIHSS score, history of hypertension, diabetes, and smoking status, in addition to BPV group (low vs. high). Adjusted odds ratios (ORs) with 95% confidence intervals (CIs) were reported. Receiver operating characteristic (ROC) curve analysis was conducted to evaluate the predictive ability of BPV for 90‐day outcomes. A p‐value of < 0.05 was considered statistically significant.

3. Results

3.1. Clinical Characteristics

A total of 144 patients with large vessel occlusion acute ischemic stroke (AIS‐LVO) who underwent mechanical thrombectomy were included in this analysis. Patients were categorized into low BPV (n = 100) and high BPV (n = 44) groups based on the level of postoperative blood pressure variability (BPV) measured within the first 24 h. There were no significant differences between the two groups regarding baseline characteristics such as age, sex distribution, prevalence of hypertension, diabetes, or smoking status (all p > 0.05). However, the high BPV group had significantly higher preoperative NIHSS scores (p = 0.021) and 90‐day mRS scores (p = 0.007) compared to the low BPV group. Detailed clinical characteristics of the two groups are summarized in Table 1.

TABLE 1.

Clinical and demographic characteristics of AIS‐LVO patients undergoing mechanical thrombectomy, divided by low and high BPV groups.

Variables	Low BPV group (n = 100)	High BPV group (n = 44)	p‐value
Age (years)	67.2	68.1	0.720
Male (%)	58 (58%)	24 (54.5%)	0.747
Hypertension (%)	72 (72%)	30 (68%)	0.634
Diabetes (%)	24 (24%)	12 (27%)	0.716
Smoking (%)	31 (31%)	14 (32%)	0.682
Pre‐op NIHSS	12.1 ± 3.9	18.8 ± 2.9	0.021
90‐day mRS	2.3 ± 1.9	3.4 ± 2.0	0.007
BPV	11.8 ± 1.7	17.9 ± 1.7	< 0.001

Note: Data are presented as mean ± standard deviation or number (percentage). p‐values represent comparisons between the two groups.

The distribution of BPV values within each group is illustrated in Figure 2. In the low BPV group, the median (IQR) BPV was 11.6 (10.5–12.9) mmHg, while in the high BPV group it was 17.8 (16.5–19.3) mmHg. The boxplot (Figure 2) confirms that the two groups were well‐separated with minimal overlap around the median cutoff (14.0 mmHg).

FIGURE 2.

Distribution of postoperative systolic BPV in low vs. high BPV groups. The central box represents the interquartile range, the line inside the box shows the median, and the whiskers indicate the 5th–95th percentiles. The low BPV group had a median (IQR) of 11.6 (10.5–12.9) mmHg, while the high BPV group had 17.8 (16.5–19.3) mmHg.

3.2. Distribution of 90‐Day mRS Scores

The distribution of 90‐day modified Rankin Scale (mRS) scores in the two BPV groups is summarized in Figure  3 . In the low BPV group (n = 100), patients with mRS 0, 1, and 2 accounted for 5%, 25%, and 30%, respectively, totaling 60% with favorable outcomes (mRS ≤ 2). In contrast, in the high BPV group (n = 44), the percentages of patients with mRS 0, 1, and 2 were 2%, 9%, and 18%, respectively, with a combined 29.5% achieving favorable outcomes. The difference in the proportion of favorable outcomes between the two groups was statistically significant ( p = 0.007). These findings indicate that lower postoperative BPV is associated with a higher proportion of patients achieving good functional recovery at 90 days after mechanical thrombectomy for AIS‐LVO.

FIGURE 3.

Distribution of 90‐day modified Rankin Scale (mRS) scores in low and high BPV groups. The horizontal stacked bar chart shows the percentages of patients with each mRS score at 90 days after mechanical thrombectomy. The low BPV group demonstrated a significantly higher proportion of patients with favorable outcomes (mRS ≤ 2) compared to the high BPV group (p = 0.007).

3.3. Receiver Operating Characteristic ( ROC ) Curve Analysis

The predictive ability of BPV for 90‐day favorable functional outcomes (mRS ≤ 2) was evaluated by ROC curve analysis. The analysis yielded an area under the curve (AUC) of 0.743 (95% CI: 0.662–0.840), suggesting that early postoperative BPV is a moderately strong predictor of good long‐term outcomes in patients with AIS‐LVO who underwent mechanical thrombectomy. Figure 4 illustrates the ROC curve, demonstrating the ability of BPV to discriminate between favorable and unfavorable functional outcomes.

FIGURE 4.

Receiver operating characteristic (ROC) curve evaluating the ability of BPV to predict favorable 90‐day outcomes (mRS ≤ 2). The area under the curve (AUC) was 0.743.

3.4. Multivariable Logistic Regression Analysis

On multivariable logistic regression analysis, adjusting for age, sex, baseline NIHSS score, hypertension, diabetes, and smoking status, high BPV was independently associated with worse outcomes. Patients in the high BPV group had significantly lower odds of achieving a favorable 90‐day outcome compared with those in the low BPV group (adjusted OR = 0.320, 95% CI: 0.156–0.679, p = 0.002). Baseline NIHSS was also a strong independent predictor (adjusted OR per 1‐point increase = 0.860, 95% CI: 0.812–0.924, p < 0.001). Other covariates, including age, sex, hypertension, diabetes, and smoking, were not significantly associated with outcome in the adjusted model.

3.5. Comparison of Functional Outcomes Across BPV and Hypertension Subgroups

To further explore the impact of BPV on functional outcomes, we performed subgroup analyses by dividing patients into those with hypertension and those without hypertension. In both hypertensive and non‐hypertensive patients, the mean 90‐day mRS score was significantly higher in the high BPV group compared to the low BPV group (p < 0.001 for hypertensive patients, p = 0.002 for non‐hypertensive patients). Additionally, the proportion of patients achieving favorable outcomes (mRS ≤ 2) was significantly different across the four groups (Chi‐square test p < 0.0001). These findings suggest that elevated early postoperative BPV is associated with worse functional outcomes regardless of hypertension status, with the impact being more pronounced in patients with hypertension. The detailed comparisons of these functional outcomes are shown in Table 2. In addition, the interaction term (BPV group × hypertension) in the multivariable logistic regression model was not statistically significant (p > 0.05).

TABLE 2.

Comparison of 90‐day functional outcomes across four groups based on BPV level and hypertension status.

Group	n	mRS 90	Good Outcome (%)
High BPV + HTN	26	3.58 ± 1.86	19
High BPV + non‐HTN	18	3.83 ± 2.28	28
Low BPV + HTN	60	1.98 ± 1.82	70
Low BPV + non‐HTN	40	2.05 ± 1.68	70
p‐value (Low vs. High BPV, HTN)			< 0.001
p‐value (Low vs. High BPV, non‐HTN)			0.002
Chi [2] p‐value (good outcome rates)			< 0.0001

Note: Data are presented as mean ± standard deviation (SD) or percentage (%).

3.6. Relationship Between BPV and Functional Outcome Groups

To provide further insight into the impact of BPV on patient recovery, we compared BPV values between those with favorable (mRS 0–2) and unfavorable (mRS 3–6) functional outcomes at 90 days. As shown in Figure 5, patients with good outcomes had significantly lower BPV (mean BPV 12.42 ± 2.24) compared to those with poor outcomes (mean BPV 15.25 ± 3.32, p < 0.0001). Furthermore, when stratifying outcome groups by BPV category, the majority of patients with favorable outcomes (82%) belonged to the low BPV group, whereas patients with unfavorable outcomes were more evenly distributed, with 56% in the low BPV group and 44% in the high BPV group.

FIGURE 5.

Proportion of patients from low and high BPV groups within outcome categories. Among those with favorable outcomes (mRS 0–2), 82% belonged to the low BPV group and 18% to the high BPV group. Conversely, in the unfavorable outcome group (mRS 3–6), 56% were low BPV and 44% were high BPV. This visualization highlights the greater likelihood of favorable outcomes in patients with lower postoperative BPV.

4. Discussion

Optimal blood pressure (BP) management following mechanical thrombectomy in AIS‐LVO patients remains a subject of ongoing research. Traditionally, guidelines have recommended maintaining systolic BP below 180 mmHg to minimize the risk of hemorrhagic transformation and other complications. However, the ENCHANTED2/MT trial challenged this approach by demonstrating that intensive BP lowering to a target of < 120 mmHg resulted in worse functional outcomes at 90 days compared to a less intensive target of 140–180 mmHg. Specifically, the intensive group exhibited higher rates of early neurological deterioration and major disability, without significant differences in symptomatic intracerebral hemorrhage [3]. These findings suggest that overly aggressive BP reduction may compromise cerebral perfusion and adversely affect recovery.

Beyond absolute BP levels, BP variability (BPV) has emerged as an independent predictor of stroke outcomes [6, 7]. Elevated BPV reflects fluctuations in BP that may impair cerebral perfusion, especially in the context of disrupted autoregulation post‐stroke [5]. Recent studies have linked higher BPV within the first 24–72 h after stroke onset to increased risks of hemorrhagic transformation, early neurological deterioration, and poor functional outcomes [8, 9, 10]. For instance, increased beat‐to‐beat BPV within 24 h of ischemic stroke onset was independently associated with a poor prognosis at 90 days [6]. Similarly, day‐by‐day BPV in the subacute stage of stroke has been associated with an increased long‐term risk of recurrent stroke. These findings underscore the importance of BP stability in the acute management of AIS‐LVO patients [11]. Consistent with these prior reports, our multivariable analysis confirmed that high BPV remained independently associated with poor functional outcome, even after adjustment for baseline NIHSS and other covariates.

Several mechanisms may explain the detrimental effects of elevated BPV on stroke outcomes. In the setting of impaired cerebral autoregulation, BP fluctuations may lead to periods of hypoperfusion and hyperperfusion, exacerbating ischemic injury and increasing the risk of hemorrhagic transformation [5, 12]. Additionally, BP variability may contribute to blood–brain barrier disruption, oxidative stress, and endothelial dysfunction, further compromising cerebral integrity [13, 14, 15]. These pathophysiological processes highlight the potential harm of BP instability, even when mean Bp‐values are within acceptable ranges [16].

Our findings align with previous studies that have identified BPV as a significant factor influencing stroke outcomes. The association between high BPV and adverse events such as infarct expansion and hemorrhagic transformation has been well documented. Moreover, the lack of benefit observed in trials targeting intensive BP lowering, such as ENCHANTED2/MT, suggests that BP stability may be more critical than achieving low BP targets. These insights advocate for individualized BP management strategies that prioritize minimizing variability to optimize patient outcomes.

Beyond these general observations, our study extends prior work by specifically contrasting with different BPV assessment windows reported in the literature. Kang et al. showed that higher BPV within the first 72 h of ischemic stroke was associated with early neurological deterioration [17], while Yousufuddin et al. demonstrated that greater in‐hospital BP fluctuations predicted poorer functional outcomes at discharge and 3 months [18]. In the subacute phase, Kang et al. found that increased BPV was linked to a higher risk of major vascular events at one year. In contrast to these studies, our analysis focuses on the immediate 24‐h postoperative period following mechanical thrombectomy, a critical time of impaired autoregulation and heightened risk of reperfusion injury [19]. By demonstrating that even in this very early window, elevated BPV is strongly associated with worse 90‐day outcomes, our findings complement and extend the existing evidence and underscore the importance of stabilizing BP variability immediately after thrombectomy.

This study has several limitations, including its retrospective, single‐center design, which may limit generalizability. BPV was assessed using intermittent measurements, potentially missing short‐term fluctuations, and detailed data on pre‐stroke blood pressure control were unavailable, limiting the classification of hypertension to prior diagnosis. Due to incomplete data, key procedural confounders—such as occlusion location, reperfusion status, anesthesia modality, and onset‐to‐reperfusion time—could not be adjusted for, introducing potential residual confounding. BPV was dichotomized using a median split, which may result in information loss and reduce the ability to identify clinically meaningful thresholds. Subgroup analyses were limited by small sample sizes, particularly in the high BPV without hypertension group, reducing statistical power and precision. Moreover, the formal test for interaction did not reach statistical significance, possibly due to insufficient subgroup sample size, and the study did not assess long‐term BPV beyond the acute phase. Future prospective studies with continuous BP monitoring, systematic collection of procedural data, and larger cohorts are needed to validate these findings and explore whether the effect of BPV varies by hypertension status.

5. Conclusion

Our study confirms that early postoperative blood pressure variability (BPV) is linked to 90‐day functional outcomes in AIS‐LVO patients after mechanical thrombectomy. Notably, the adverse effect of elevated BPV was more significant in patients with pre‐existing hypertension, highlighting a potential role for individualized BP management. Unlike previous studies, we focused on early postoperative BPV and its interaction with hypertension status, providing new insights into BP management after thrombectomy. Future research should validate these findings and explore ways to minimize BPV to improve recovery in this high‐risk population.

Author Contributions

Yunpeng Liu and Yiqi Liu contributed to the study conception, design, data analysis, and manuscript drafting. Yang Wang provided project funding support. Other co‐authors contributed to patient enrollment, data collection, and critical review of the manuscript. All authors read and approved the final version of the manuscript.

Funding

This study was supported by the Capital Health Research and Development of Special Fund (No. 2022–2–2034) and the National Natural Science Foundation of China (No. 82201444).

Ethics Statement

This study was approved by the Committee on Ethics of Beijing Chao‐yang Hospital, Capital Medical University (No. 2022‐KE‐268). All human participants provided their consent.

Conflicts of Interest

The authors declare no conflicts of interest.

Data Availability Statement

The data that support the findings of this study are available on request from the corresponding author. The data are not publicly available due to privacy or ethical restrictions.