Four‐year prospective study of the influence of elevated serum lipoprotein (a) concentration on ischemic heart disease and cerebral infarction in elderly patients with type‐2 diabetes

Background:  The purpose of the present paper was to elucidate the influence of an elevated serum lipoprotein (a) (Lp(a)) concentration on the incidence of ischemic heart disease (IHD) and perforating artery occlusion-type cerebral infarction (CI) in elderly patients with type-2 diabetes. Methods:  The serum Lp(a) levels in type-2 diabetic subjects aged ≥60 years (n = 158; 81 male, 77 female) were measured. At the commencement of the study, subjects were allocated on the basis of past history of CI to a CI– or CI+ group, and on the basis of past history of angina pectoris or myocardial infarction to an IHD– or IHD+ group. They were followed up prospectively for 4 years and the incidences of IHD and CI were monitored. Diagnoses of CI were confirmed by computed tomography (CT), and of myocardial infarction by electrocardiography and blood chemistry. Serum Lp(a) levels of ≥ 20 mg/dL were considered elevated, and < 20 mg/dL as normal. Kaplan–Meier survival analysis (log–rank test) was used to assess the time to event rate stratified by an Lp(a) cut-off of 20 mg/dL. The predictive value for CI or IHD events was assessed by multiple logistic regression analysis. Results:  The probability of IHD events was significantly higher in the elevated Lp(a) group than in the normal Lp(a) group without a history of IHD (P < 0.001; log–rank test), but was similar in the two subgroups of subjects with a history of IHD. No significant difference was seen between the elevated Lp(a) and normal Lp(a) groups in the probability of CI events, with or without a history of CI. On multiple logistic regression analysis, Lp(a), hyperlipidemia and a history of IHD were significant predictors of IHD, whereas hypertension, hyperlipidemia and a history of CI were significant predictors of CI. Conclusion:  These results indicate that an elevated serum Lp(a) concentration is an independent risk factor for IHD, but not for perforating artery occlusion-type CI, in elderly patients with type-2 diabetes.