Can bad cholesterol get worse? L5, the most electronegative LDL fraction isolated chromatographically, was found to be significantly elevated in patients with STEMI compared with normal controls.¹  Ex vivo, L5 not only enhanced adenosine 5′-diphosphate-stimulated platelet aggregation, platelet P-selectin expression, and GP IIb/IIIa activation but also induced both endothelial tissue factor and P-selectin expression and apoptosis. Together, these data provide mechanistic details of the thrombophilic state created by L5 that could cause a domino effect and produce an occlusive coronary artery thrombosis resulting in an STEMI. (A) Coronary angiogram showing an occluded left anterior descending coronary artery (LAD) during STEMI and inserts showing balloon percutaneous coronary intervention (PCI) and the angiogram after opening the LAD. (B) Scanning electron micrograph of bisected LAD from a pig with an occlusive thrombosis (T) causing an STEMI. (C) Electrocardiogram showing a STEMI. Professional illustration by Debra T. Dartez.