Oxidized LDL, lipoprotein (a) and other emergent risk factors in acute myocardial infarction (FORTIAM study).

INTRODUCTION AND OBJECTIVES: To determine the prevalence of acute myocardial infarction (AMI) without classical risk factors, and to ascertain whether affected patients exhibit a higher prevalence of emergent risk factors and whether the presence of specific emergent risk factors influence prognosis at 6 months.

METHODS: The FORTIAM (Factores Ocultos de Riesgo Tras un Infarto Agudo de Miocardio) study is a multicenter cohort study that includes 1371 AMI patients who were admitted within 24 hours of symptom onset. Strict definitions were used for classical risk factors and the concentrations of the following markers were determined: lipoprotein (a) [Lp(a)], oxidized low-density lipoprotein (oxLDL), high-sensitivity C-reactive protein, fibrinogen, homocysteine and antibody to Chlamydia. The end-points observed during the 6-month follow-up were death, angina and re-infarction.

RESULTS: The prevalence of AMI without classical risk factors was 8.0%. The absence of classical risk factors did not affect the 6-month prognosis. The only emergent risk factors independently associated with a poorer prognosis were the Lp(a) and oxLDL concentrations. Cut-points were determined using smoothing splines: 60 mg/ dL for Lp(a) and 74 U/L for oxLDL. The associated hazard ratios, adjusted for age, sex and classical risk factors, were 1.40 (95% confidence interval, 1.06-1.84 ) and 1.48 (95% confidence interval, 1.06-2.06), respectively.

CONCLUSIONS: The proportion of AMI patients without classical risk factors was low and their prognosis was similar to that in other AMI patients. Both oxLDL and Lp(a) concentrations were independently associated with a poorer 6-month prognosis, irrespective of the presence of classical risk factors.