Abstract 190: Groups IIA, IVA and V Phospholipase A2 in Coronary Thrombus Are Associated With Recurrent Cardiac Events and Development of Atherosclerosis in the Culprit Coronary Artery After Acute Myocardial Infarction
Background: The intracoronary thrombus is a source of active lipid mediators including eicosanoids that play critical roles in the pathogenesis of acute myocardial infarction (AMI). Eicosanoids are derived from arachidonic acid generated by phospholipase A2 (PLA2). This study examined whether PLA2 were expressed in aspirated coronary thrombi and whether PLA2 expression in the thrombi may be related to the recurrence of cardiac events and development of atherosclerosis in the culprit coronary artery after AMI.
Methods: Intracoronary thrombi were obtained using an aspiration catheter at the emergent PCI from 48 patients with AMI who had successful treatment with PCI. The presence of groups IB, IIA, IID, IIE, IIF, III, IVA, V, VI, VII, X and XIIA PLA2 was examined using immunohistochemical staining in all of the thrombi obtained. Repeated intravascular ultrasound in the culprit coronary artery was performed at emergent PCI and 6 months later in a subgroup of 20 patients.
Results: Each of the 12 subtypes of PLA2 was detected by its immunoreactivity in 2 - 6% of total nucleated cells and 16 - 39% of platelet area (CD42b-positive area). COX-1, COX-2 and 5-LOX, downstream enzymes for PLA2 in the arachidonic acid cascade, were co-localized with PLA2. During 6 months of follow-up, 11 patients had cardiac events. Percentages of platelet areas immunopositive for groups IIA, IVA and V PLA2 were significantly higher in patients with cardiac events (n = 11) than without (n = 37) (% of CD42b-positive areas: 36% vs. 14%, 55% vs. 32% and 54% vs. 27%, respectively, p < 0.05 in all). Similarly, percentages of nucleated cells immunopositive for groups IIA, IVA and V PLA2 were also higher in thrombi from patients with cardiac events than without (p < 0.05 in all). Percentagesby which atheroma volumes and vessel volumes increased in the native coronary segments distal to the culprit coronary lesion were significantly and positively correlated with percentages of nucleated cells immunopositive for groups IIA (r = 0.60 and 0.52, respectively), IVA (r = 0.55 and 0.46) and V PLA2 (r = 0.45 and 0.48).
Conclusion: Groups IIA, IVA and V PLA2 in coronary thrombi may play a role in recurrence of cardiac events and development of atherosclerosis in the culprit coronary artery in AMI survivors.
- © 2013 by American Heart Association, Inc.