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Apolipoproteins as risk indicators of ischemic heart disease
Insights
Apolipoprotein B (apo B) and related ratios like TC/apo B show promise in predicting coronary risk, even in individuals with normal lipid levels. These markers offer improved accuracy over traditional lipid measurements for cardiovascular risk assessment.
Area of Science:
- Cardiovascular Medicine
- Biochemistry
- Lipid Metabolism
Background:
- Coronary risk assessment often relies on lipid levels, but ~50% of at-risk individuals have normal lipid profiles.
- Apolipoproteins, including apo A1, apo B, and apo E, are emerging as potentially superior indicators of cardiovascular risk.
- Apo E sialylation is implicated in its metabolism and may be altered in diabetes.
Purpose of the Study:
- To evaluate the diagnostic validity of apolipoprotein profiles and lipid parameters for predicting coronary risk.
- To identify reliable markers for coronary risk assessment in both hyperlipidemic and normolipidemic states.
- To investigate the role of apo E sialylation in diabetes and its potential impact on metabolism.
Main Methods:
- Studied 64 male myocardial infarction survivors and 60 matched controls (Group I).
- Selected a subgroup (Group II) with normal total cholesterol (TC) and triglycerides (TG) for further analysis.
- Calculated sensitivities, specificities, efficiencies, and predictive values for various lipid and apolipoprotein parameters.
Main Results:
- Apolipoprotein B (apo B), TC/apo B ratio, and HDL-C/apo B ratio demonstrated suitability for detecting coronary risk.
- The TC/apo B ratio achieved accurate reclassification of 71-76% of controls and 79% of survivors.
- Increased apo E sialylation was observed in individuals with insulin-dependent (IDDM) and non-insulin-dependent diabetes mellitus (NIDDM).
Conclusions:
- Apolipoprotein B and specific ratios involving apo B are effective predictors of coronary risk, outperforming traditional lipid measures in certain populations.
- The TC/apo B ratio offers a valuable tool for reclassifying individuals based on their coronary risk.
- Altered apo E sialylation in diabetes warrants further investigation regarding its metabolic implications.
Abstract:
About 50% of the individuals with a coronary risk show lipid levels within the normal range. Therefore, apolipoprotein profiles could be better risk indicators than TC or TG. Apolipoproteins generally discussed in this context are apo A1, apo B, and apo E. Their diagnostic validity, however, is ambigously evaluated. The individual iso-protein pattern of apo E is important for the differential diagnosis of the type III hyperlipidemia with its strong predisposition for premature atherosclerosis. Moreover, the extent of the apo E sialylation seems to be important because the modification of apo E by sialic acid alters its metabolism. Our date provide evidence that in IDDM and NIDDM the degree of apo E sialylation is increased. Concerning apo A1 and B we tried to find out parameters suitable for the prediction of the coronary risk both in the hyperlipidemic and the normolipidemic state. 64 male survivors of a myocardial infarc"ion and 60 matched controls were included in the study (group I). From group I a supopulation showing non-pathological values for TC and TG was selected (group II with 31 survivors and 44 controls). The diagnostic validity of the parameters apo A1, apo B, TC, HDL-C, apo A1/apo B, TC/apo B, HDL-C/apo B, TG, TG/apo A1, TG/HDL-C, TC-HDL-C/apo B determined by calculation of their sensitivities, specificities, efficiencies, and predictive values. Only the parameters TC/apo B, HDL-C/apo B, and apo B were suitable in the order given for detection of the coronary risk. Using the TC/apo B ratio 71-76% of the controls and 79% of the survivors could be exactly reclassified independent of the group they belonged to.(ABSTRACT TRUNCATED AT 250 WORDS)