Anticardiolipin antibodies and acute myocardial infarction in non-systemic lupus erythmatosus patients: a controlled prospective study. 
To examine the prevalence of anticardiolipin antibodies (ACLA) in relatively young patients with acute myocardial infarction (MI) and their role in subsequent coronary and thromboembolic events in the post-MI period.  In 124 relatively young survivors (aged 65 or younger) of acute MI, ACLA were measured in a controlled prospective study on admission and 3 months later.  Myocardial reinfarction and thromboembolic events during a mean follow-up period of 19 +/- 3 months were diagnosed by standard tests.  Seventeen (14%) of the 124 patients were ACLA positive (either IgM or IgG) upon admission compared with 2 out of 76 (3%) of the control group matched for age and coronary risk factors (P < 0.01).  The levels of ACLA remained unchanged in all but 1 patient 3 months later.  During the follow-up period the rate of thromboembolic events and myocardial reinfarction was significantly higher in the ACLA-positive patients as compared with the ACLA-negative group: 41% versus 4% (P < 0.0001) and 35% versus 10% (P < 0.05), respectively.  Using logistic regression, high titer of ACLA was found to be the only independent risk factor for subsequent thromboembolic events or myocardial reinfarction after acute MI.  High prevalence of ACLA was found in relatively young survivors of acute MI.  The presence of ACLA is a marker for increased risk of subsequent myocardial reinfarction and thromboembolic events after acute MI.