Link Between Metabolic Syndrome and Atherothrombotic Stroke
Link Between Metabolic Syndrome and Atherothrombotic Stroke
In the present study, MetS showed a significant positive association with multiple lesions of intracranial atherothrombotic stroke in women, but not men, who were in-patients admitted to the hospital with the first-ever stroke. The observation that MetS may be an underlying entity for the formation of intracranial stroke multiplicity with a possible gender bias is new information. Atherothrombotic stroke is considered a treatable target, while in patients suffering from multiple lesions of stroke, it may lead to multiple neurological and/or cognitive dysfunctions. Thus, the treatment of MetS can be significant for preventing atherothrombotic stroke multiplicity and subsequent dysfunctions in women in particular.
A positive association between MetS and atherothrombotic stroke has been reported, and the etiopathological mechanisms of atherothrombosis (e.g., via vasomotor reactivity impairment, insulin resistance, inflammation, oxidative stress, platelet activation and hypercoagulation) have been proposed. Under the etiopathology, atherothrombotic stroke may suddenly occur in multiple lesions, and/or the repeated stroke formation may be unnoticed in some cases whose lesions are multiple, like a silent brain infarct. Gender differences exist in the clinical features of MetS, stroke and their association thereof; that is, the influences of MetS on stroke may be greater in Japanese women than in men. According to these literature findings, the associations among MetS and atherothrombotic stroke multiplicity observed in the present survey appear to be plausible. On the other hand, though the impact of MetS on multiple lesions in men was not significant and weaker than that in women, the OR level was over 1.5 (Table 2) and confirmation may be repeatedly required in men. Mutifaceted studies including etiopathological factors and larger samples in both genders will be necessary to understand the findings.
The clinical significance of MetS or each component of MetS on the atherosclerotic outcomes is poorly understood. In the present study, the analysis of each component of MetS with multiple lesions showed that dyslipidemia in particular (such as high TG and/or low HDL-C) was positively associated with multiple lesions in both genders. Such a significant influence of dyslipidemia on stroke can be supported by previous studies, although these studies did not examine stroke multiplicity. In addition to the treatment of MetS, a consideration of atherogenic dyslipidemia could be particularly pivotal when subjects do not necessarily manifest a complete MetS phenotype.
There are several limitations associated with this study. The study had a retrospective design based on clinical data obtained from medical records. Although the multiple lesions detected in the present study could include old infarcts, the clear discrimination between new and old infarcts was not always made (it was difficult to discriminate them based on a retrospective description of medical records). The number of multiple lesions may also be useful information; however, it could not completely be collected in this survey. The additional information (e.g., serum low-density lipoprotein cholesterol, smoking and alcohol intake) was not fully collected for all patients. Information bias may therefore affect the study results. The study was conducted in a single hospital, which could lead to selection bias. Furthermore, there may be ethnic disparities in the relevance of MetS on stroke multiplicity and the definition of MetS itself may affect the results. These issues should be addressed in future studies with prospective and multicentric designs with various populations.
In summary, MetS may have a pathophysiology associated with intracranial atherothrombotic stroke multiplicity in women in particular. Future studies are warranted to confirm the findings.
Discussion
In the present study, MetS showed a significant positive association with multiple lesions of intracranial atherothrombotic stroke in women, but not men, who were in-patients admitted to the hospital with the first-ever stroke. The observation that MetS may be an underlying entity for the formation of intracranial stroke multiplicity with a possible gender bias is new information. Atherothrombotic stroke is considered a treatable target, while in patients suffering from multiple lesions of stroke, it may lead to multiple neurological and/or cognitive dysfunctions. Thus, the treatment of MetS can be significant for preventing atherothrombotic stroke multiplicity and subsequent dysfunctions in women in particular.
A positive association between MetS and atherothrombotic stroke has been reported, and the etiopathological mechanisms of atherothrombosis (e.g., via vasomotor reactivity impairment, insulin resistance, inflammation, oxidative stress, platelet activation and hypercoagulation) have been proposed. Under the etiopathology, atherothrombotic stroke may suddenly occur in multiple lesions, and/or the repeated stroke formation may be unnoticed in some cases whose lesions are multiple, like a silent brain infarct. Gender differences exist in the clinical features of MetS, stroke and their association thereof; that is, the influences of MetS on stroke may be greater in Japanese women than in men. According to these literature findings, the associations among MetS and atherothrombotic stroke multiplicity observed in the present survey appear to be plausible. On the other hand, though the impact of MetS on multiple lesions in men was not significant and weaker than that in women, the OR level was over 1.5 (Table 2) and confirmation may be repeatedly required in men. Mutifaceted studies including etiopathological factors and larger samples in both genders will be necessary to understand the findings.
The clinical significance of MetS or each component of MetS on the atherosclerotic outcomes is poorly understood. In the present study, the analysis of each component of MetS with multiple lesions showed that dyslipidemia in particular (such as high TG and/or low HDL-C) was positively associated with multiple lesions in both genders. Such a significant influence of dyslipidemia on stroke can be supported by previous studies, although these studies did not examine stroke multiplicity. In addition to the treatment of MetS, a consideration of atherogenic dyslipidemia could be particularly pivotal when subjects do not necessarily manifest a complete MetS phenotype.
There are several limitations associated with this study. The study had a retrospective design based on clinical data obtained from medical records. Although the multiple lesions detected in the present study could include old infarcts, the clear discrimination between new and old infarcts was not always made (it was difficult to discriminate them based on a retrospective description of medical records). The number of multiple lesions may also be useful information; however, it could not completely be collected in this survey. The additional information (e.g., serum low-density lipoprotein cholesterol, smoking and alcohol intake) was not fully collected for all patients. Information bias may therefore affect the study results. The study was conducted in a single hospital, which could lead to selection bias. Furthermore, there may be ethnic disparities in the relevance of MetS on stroke multiplicity and the definition of MetS itself may affect the results. These issues should be addressed in future studies with prospective and multicentric designs with various populations.
In summary, MetS may have a pathophysiology associated with intracranial atherothrombotic stroke multiplicity in women in particular. Future studies are warranted to confirm the findings.
