Relationships between lipoprotein components and risk of myocardial infarction: age, gender and short versus longer follow-up periods in the Apolipoprotein MOrtality RISk study (AMORIS).

OBJECTIVES: Examine and compare lipoprotein components associated with fatal and nonfatal acute myocardial infarction (AMI) by time period in the Apolipoprotein MOrtality RISk (AMORIS) Study.
DESIGN: Prospective follow-up study of nonfatal and fatal myocardial infarction through linkage with Swedish hospital discharge and Swedish mortality registers.
SETTING: Measurements of lipoprotein components from health check-ups in the larger Stockholm area.
SUBJECTS: The AMORIS subjects (n = 149 121) free of AMI at blood sampling were followed from 1985 to 2002 with respect to n = 6794 first cases of AMI.
RESULTS: Hazard ratios of nonfatal and fatal AMI by lipoprotein parameters were highly significant and about equally strong in both genders. Apolipoprotein B (apoB), nonhigh density cholesterol and low density cholesterol predicted nonfatal AMI (NFAMI) better than fatal AMI, but high density cholesterol or apolipoprotein A-1 did not. Atherogenic components were weaker predictors after 1997 than before. In multivariate analyses apoB/apoA-1 was a better predictor than TC/HDL-C. ApoB/apoA-1 added clinically significant information to TC/HDL-C in men as reflected by a net reclassification improvement (NRI) of 9.4% (P < 0.0001).
CONCLUSION: ApoB, apoB/apoA-1 and non-HDL-C were found about equally predictive with LDL-C being slightly less, but multivariate analyses showed apoB/apoA-1 to be the strongest predictor. Attenuation of prediction ability between nonfatal and fatal AMI may be due to modern treatment of CHD after a NFAMI and attenuation of hazard ratios after 1997 may be due to selection of lower risk subjects surviving to 1997.