Lipoprotein(a) and apolipoproteins B and A-I after acute myocardial infarction

To assess the temporal behaviour of plasma lipoprotein(a) [Lp(a)]--a low density lipoprotein-like particle whose plasma levels are associated with atherosclerosis risk--and apolipoproteins (apo) B and A-I (the major protein components of low and high density lipoproteins, respectively) in acute myocardial infarction (AMI), and to determined the effect of tissue plasminogen activator (tPA) on them.

Serial Lp(a), apoB and apoA-I determinations were obtained over eight days in 19 AMI patients who were part of a randomized, placebo (n = 7) controlled trial of tPA (n = 12).

At 48 h postinfarct, plasma Lp(a) and apoB concentrations were, respectively, 20% (24.9 +/- 3.0 to 19.9 +/- 2.9 mg/dL, P < 0.05) and 28% (1.37 +/- 0.10 to 0.99 +/- 0.11 mM/L, P < 0.05) below baseline values. ApoA-I concentrations were unchanged at 48 h postinfarct. At 192 h postinfarct, Lp(a) rebounded to 36% above baseline (24.9 +/- 3.0 to 33.9 +/- 3.9 mg/dL, P < 0.05), apoB returned to baseline (1.37 +/- 0.10 versus 1.33 +/- 0.11 g/L, P < 0.05) and apoA-I was 15% below baseline (1.43 +/- 0.06 to 1.21 +/- 0.06 g/L, not significant). Administration of tPA had no effect on any of these changes.

Plasma Lp(a) and apolipoproteins undergo shifts from baseline values in the postinfarct period and tPA has no effect on these variations.