The Relationship Between The Lipoprotein(a) Levels And Intra-and Extracranial Vascular Stenosis

Background and Purpose Ischemic cerebrovascular disease (ICD) is considered to be one of the most common causes of mortality and long term severe disability. And intra- and extracranial vascular stenosis is a important risk factor for ICD. Therefore the prevention of intra- and extracranial vascular stenosis is important. There is evidence that elevated plasma levels of Lp (a)≥300mg/l have been linked to an increased risk of ICD. Lp (a) contains a biochemical moiety similar in structure to low-density lipoprotein and several domains similar to plasminogen, a proenzyme related to fibrinolysis. Combining a proatherogenic factor with an antifibrinolytic factor makes Lp (a) an interesting candidate for a link between plaque and stenosis and a likely risk factor for thrombotic events. Our aim was to assess the effect of Lp (a) on carotid plaque and intra- and extracranial vascular stenosis.Methods 290 patients (210 male, 80 female) that admitted to our institute with ICD from Jan 2008 to Jan 2009 were involved in our study. Among these patients, 202 of them were diagnosed as intracranial ischemic (CI), 50 were diagnosed as transient ischemic attacks (TIA) and 38 were diagnosed as vertebrobasilar artery insufficiency. The average age was 59.2±11.3 years (25～90 year). The patients were divided into 3 groups according to the degree of vascular stenosis, increased thickness of carotid artery intima and the number of atherosclerotic plaque: (1) Without carotid artery intima increased and vascular stenosis (control group); (2) With carotid artery intima increased or atherosclerotic plaque forming but without vascular stenosis (plaque group); (3) With vascular stenosis in intracranial artery or extra cranial artery (vascular stenosis group).Results (1) The level of Lp(a) in control group (43 patients, 14.8%), plaque group (88 patients, 30.3%) and vascular stenosis group (159 patients, 54.8%) were 0.109±0.071g/L, 0.188±0.136g/L and 0.158±0.135g/L, respectively. There were significant differences in statistic between control group and plaque group or vascular stenosis group in Lp(a) level. The concentration of Lp (a) was significant correlated with plaque forming and vascular stenosis by using multiplicity analysis. The increased ratio of Lp (a) concentration in control group, plaque group and vascular stenosis group were 4.7%, 13.6% and 13.2%, respectively, compared with the normal level (Lp(a)≥0.30g/L). (2) In the vascular stenosis group, 39 patients were single extracranial artery stenosis (24.5%), 88 patients were single intracranial artery stenosis (61.6%), and 22 patients were both of the extra cranial and intracranial artery stenosis (13.8%). The ratio of intracranial artery stenosis was larger than extra intracranial artery stenosis. The middle cerebral artery stenosis was 39.6%, which was the largest partition in all the cases. There was no significant difference in incidence rate between right and left lateral artery stenosis. Compared with intracranial artery stenosis, the extra cranial artery stenosis incidence rate showed increased as the risen of age. (3) There was no significant difference in Lp(a) levels between single intracranial artery stenosis group (0.161±0.140 g/L) and single extra cranial artery stenosis group (0.148±0.118 g/L) (P=0.607). The risen of Lp(a) level was an risk factor of single intracranial and extra cranial artery stenosis by using the method of multiple factor regression analysis. The results suggested that there were no significant correlations between Lp(a) level and the degree or the number of vascular stenosis among the patients of single intracranial artery stenosis and total vascular stenosis.Conclusion (1) Lp (a) was a significant independent predictor of carotid plaque and intra- and extracranial vascular stenosis in ICD, but there was no significant difference between intra- and extracranial vascular stenosis. (2) The incidence rate of intracranial artery stenosis was significantly higher than the extra cranial artery stenosis in ICD patients, and rate of middle cerebral artery stenosis was the largest partition. The morbidity of extra cranial artery stenosis increased as the risen of age. (3) There were no significant correlations between Lp(a) level and the degree or the number of vascular stenosis among the patients of single intracranial artery stenosis and total vascular stenosis.