This study aimed to elucidate the impact of the SHR on END in patients with cerebral infarction who underwent intravenous thrombolysis without hemorrhagic transformation. Additionally, the study sought to identify risk factors associated with END in this patient population. Our findings indicate that both HbA1c and SHR are significant predictors of END, with SHR demonstrating a particularly strong association. Notably, SHR exhibited a higher AUC compared to HbA1c, suggesting that SHR is a more reliable marker for distinguishing END. These results highlight the importance of monitoring both HbA1c and SHR in patients with acute non-cardiogenic cerebral infarction who have not experienced hemorrhagic transformation after intravenous thrombolysis. Such monitoring may aid in predicting and potentially mitigating the risk of END. Our study underscores the need for further research to explore the mechanisms underlying these associations and to develop targeted interventions for patients at risk of END.
Stroke remains a major global health issue, ranking as the second leading cause of death and significantly contributing to disability worldwide(11). It accounts for approximately 11% of all fatalities, with substantial variations in prevalence across different regions and demographic groups(12). Notably, stroke incidence is higher in low- and middle-income countries compared to high-income nations, with age-standardized incidence rates in less affluent areas being nearly twice as high as those in more affluent regions(13, 14). This discrepancy underscores the influence of socioeconomic factors on stroke vulnerability.
Ischemic stroke, characterized by disrupted blood supply to the brain, requires prompt medical intervention to minimize cerebral injury and improve patient outcomes(15). The primary treatments for AIS include reperfusion therapy, which consists of intravenous thrombolysis with recombinant tissue plasminogen activator (rtPA) and mechanical thrombectomy(16). These therapies aim to restore blood flow to affected brain regions. Despite the potential benefits of acute interventions, their effectiveness is limited by a narrow therapeutic window, the risk of hemorrhagic transformation, and the varied etiologies of stroke. Recent studies have shown that tirofiban can reduce the risk of END, although the incidence of intracranial hemorrhage was slightly higher with tirofiban(17, 18).
Complications following a stroke significantly contribute to elevated morbidity and mortality rates, with approximately 5.5 million stroke-related deaths reported globally each year(5). END, characterized by the worsening of neurological status within the first few hours or days post-stroke, affects approximately 10–20% of patients(19). END is linked to poorer functional outcomes, increased disability, and higher mortality rates(18, 20). Preventive strategies for END emphasize maintaining hemodynamic stability, rigorous blood glucose control, and close monitoring for any signs of deterioration(21). The variability in the incidence of END underscores the necessity for personalized care and highlights the need for continued research to identify high-risk individuals and develop targeted interventions(13).
The pathophysiology of END in ischemic stroke is multifaceted and not fully understood. END can arise from various mechanisms, including the expansion of the initial infarct due to ongoing ischemia, unstable atherosclerotic plaques, cerebral edema leading to increased intracranial pressure, hemorrhagic transformation within the infarcted area, and secondary embolic events(22). Additionally, post-ischemic inflammatory responses can exacerbate tissue damage, significantly contributing to the onset of END(23). Despite extensive research, substantial knowledge gaps remain regarding the specific triggers and underlying mechanisms of END. The heterogeneity of stroke pathology, along with the influence of comorbidities and pre-existing conditions, complicates the identification of consistent predictors or therapeutic targets for END(22). Moreover, the variability in the timing of neurological decline among patients presents challenges in determining optimal intervention windows.
Current research faces several challenges, including the rapid and accurate identification of patients at high risk for END, the development of effective therapeutic strategies to prevent or mitigate END, and the establishment of standardized criteria for defining and evaluating neurological decline. Therefore, managing END in ischemic stroke continues to be a significant challenge in stroke care(24, 25), underscoring the urgent need for ongoing research to elucidate the underlying mechanisms and develop effective prevention and treatment strategies. While many studies have focused on END related to hemorrhagic transformation following thrombolysis in acute cerebral infarction, there is a notable lack of research on END associated with non-hemorrhagic transformation after thrombolysis in patients with acute cerebral infarction caused by non-cardiogenic embolisms(26).
The SHR is a metric used to assess the degree of hyperglycemia in acutely ill patients relative to their estimated baseline glucose levels. SHR aims to differentiate between true diabetic hyperglycemia and stress-induced glucose elevations, which have distinct implications for patient outcomes and management approaches(27). Recently, SHR has gained recognition as an important prognostic indicator. Several studies have demonstrated that a higher SHR is associated with poorer outcomes in patients with acute coronary syndromes (ACS)(28). Elevated SHR may indicate a higher risk of mortality, increased incidence of heart failure, and a greater likelihood of adverse cardiovascular events(29).
The mechanisms linking an elevated SHR to adverse cardiovascular outcomes are complex and multifaceted(30). Stress-induced hyperglycemia can exacerbate oxidative stress and inflammation, leading to endothelial dysfunction and plaque instability(31). Additionally, acute hyperglycemia may negatively impact myocardial function by altering myocardial metabolism and increasing the susceptibility of cardiomyocytes to ischemic injury(32). Elevated stress-related hyperglycemia is often associated with increased levels of stress hormones such as cortisol and catecholamines, which can further exacerbate cardiovascular instability and contribute to poor outcomes(27).
The SHR has been extensively examined in the context of AIS and transient ischemic attacks (TIA). However, the influence of SHR on stroke prognosis remains debatable(4). Previous research has often focused on absolute hyperglycemia as a determinant of stroke outcomes, overlooking variations in patients' baseline blood glucose levels. This oversight could confound the analysis of hyperglycemia's impact on prognosis(33). To address this, SHR incorporates baseline glycemia into analyses, emphasizing the relative increase in blood glucose levels. Several studies have underscored the importance of SHR in predicting both short-term and long-term outcomes for AIS patients(34). Elevated SHR has been linked to more severe initial neurological deficits, a higher incidence of END, and poorer functional outcomes at discharge and follow-up(6). Despite its prognostic value, the use of SHR in ischemic cerebrovascular disease is still debated. A major point of contention is the variability in threshold values used to define elevated SHR, which differs widely across studies and populations. Furthermore, there is ongoing debate about whether adverse outcomes in AIS patients are primarily driven by hyperglycemia itself or by the underlying stress response. Some experts advocate targeting hyperglycemia to improve patient outcomes, while others suggest that focusing on the overall stress response might be more beneficial(35).
In this study, we found that the SHR was independently associated with adverse clinical outcomes, even after adjusting for other clinical risk factors. Both hyperglycemia at presentation and the increase in glucose levels, as indicated by SHR, were linked to poor functional outcomes. A high SHR may contribute to dysregulated inflammatory responses, which can lead to cerebral vasoconstriction and reduced cerebral blood flow, thereby impairing functional recovery(36). This response is triggered by a surge in catecholamines, cortisol, and other inflammatory mediators, which promotes rapid glycogenolysis and the release of glucose from hepatic glycogen stores into the bloodstream. Consequently, it appears that acute fluctuations in glucose concentration, rather than persistently high blood glucose levels, are responsible for the observed adverse clinical outcomes.
The exact mechanisms by which the SHR influences outcomes in ischemic cerebrovascular disease remain under investigation, but several pathways are believed to be involved. Firstly, stress-induced hyperglycemia is associated with heightened inflammatory and neurohormonal responses, increased endothelial cell apoptosis, and elevated oxidative stress(37). This oxidative stress activates matrix metalloproteinase gelatinase B (MMP-9), compromising the integrity of the blood-brain barrier (BBB) and leading to increased BBB permeability, which heightens the risk of brain edema and hemorrhage following reperfusion(38). It has been shown that stress hyperglycemia predicts hemorrhagic transformation in AIS patients(39). Secondly, stress hormones stimulate hepatic gluconeogenesis while inhibiting glucose uptake in peripheral tissues(40). Pro-inflammatory cytokines can enhance the expression and membrane localization of glucose transporters GLUT-1 and GLUT-3, which promotes glucose uptake by insulin-independent tissues, including the central nervous system(41). Excessive cellular glucose leads to increased brain lactate production, which may transform asymptomatic tissue into symptomatic tissue(42). Thirdly, both acute and chronic hyperglycemia contribute to a prothrombotic state and may promote thrombus extension, which is closely linked to END(4). This involves hyperglycemia and hyperinsulinemia elevating the expression of plasminogen activator inhibitor-1 (PAI-1), thereby reducing rt-PA activity(43). Additionally, hyperglycemia can disrupt the endothelial glycocalyx layer, release coagulation factors, and increase platelet-endothelial adhesion(44). The mechanisms underlying hyperglycemia-induced hypercoagulability are complex and warrant further investigation. Furthermore, stress hyperglycemia may reflect transient glycemic variability, which specifically induces oxidative stress(45). Previous research has demonstrated that greater glycemic variability in AIS patients is associated with lower rates of neurological improvement during hospitalization, potentially due to increased oxidative stress(46). Finally, the extent of stress hyperglycemia may serve as an indicator of disease severity; in AIS patients, it can reflect the degree of ischemic injury, with severe neurological impairment closely related to endothelial dysfunction.
Our study also found that Hemoglobin A1c (HbA1c) can serve as a predictor of neurological deterioration following thrombolysis in patients with AIS. HbA1c is a form of hemoglobin covalently bonded to glucose, reflecting average blood glucose levels over the preceding two to three months, which corresponds to the lifespan of red blood cells(47). This biomarker is commonly used in clinical settings to monitor long-term glycemic control in diabetic patients(48, 49). Elevated HbA1c levels have been associated with the occurrence, progression, and prognosis of ischemic stroke. Specifically, high HbA1c levels correlate with an increased risk of both developing ischemic stroke and experiencing poorer outcomes after a stroke event(50). The mechanisms by which HbA1c could predict END in AIS patients are complex. Elevated HbA1c levels indicate chronic hyperglycemia, which may exacerbate ischemic injury through several pathways(51). Chronic hyperglycemia can lead to endothelial dysfunction, increased oxidative stress, and elevated levels of inflammatory markers. These factors collectively contribute to increased vulnerability of cerebral vasculature and neural tissue during an ischemic event. Furthermore, high HbA1c levels can promote a prothrombotic state, raising the risk of thrombus formation and extension, which may result in more extensive brain damage and poorer recovery outcomes(52). Elevated HbA1c may also reflect poor pre-stroke glycemic control, indicating underlying vascular pathology that predisposes patients to ischemic damage and its complications. Additionally, pre-existing hyperglycemia might impair the efficacy of thrombolytic therapy by increasing blood-brain barrier permeability, thereby raising the risk of hemorrhagic transformation.
However, HbA1c measurement is not without limitations. Its reliability as a marker can be compromised under various conditions, including significant anemia, hemoglobinopathies, recent blood transfusions, and chronic kidney disease. These conditions can affect the lifespan of red blood cells or alter hemoglobin structure, potentially leading to misleading HbA1c levels(53). Therefore, while HbA1c is a convenient and widely accessible marker, clinicians must be aware of these potential confounders when interpreting results(54).
This study had several limitations. It is a retrospective observational study with a modest sample size and was conducted at a single center. Additionally, patients who received endovascular therapy after intravenous thrombolysis (IV-rtPA) were excluded, which may have introduced selection bias. The study relied on admission blood glucose levels to calculate the SHR without considering glycemic changes and control at other time points. Furthermore, diabetes diagnosis was based on past medical history and HbA1c levels, without a detailed assessment of the patients' prior glycemic status. Despite these limitations, the study's strengths include a rigorous selection process and the inclusion of patients from a well-defined center.
In conclusion, this study suggests that SHR can be a valuable predictor of END in patients with AIS following intravenous thrombolysis. Large-scale, multicenter studies are still needed to further elucidate the role of SHR in predicting END in these patients.