Percutaneous transluminal coronary angioplasty (PTCA) involves the advancement of balloon tipped catheter into the area of coronary narrowing, inflation of the balloon and then subsequent removal of catheter after balloon deflation. Stent thrombosis can be a catastrophic in post PCI subjects as complete blockage can lead to sudden death or high mortality rate. From the studies it showed that PCI with stenting the thrombotic event rates were excessively high and were initially lowered with aggressive anticoagulation with low molecular dextran, dipyridamole and warfarin which also included longer periods of hospitalizations and higher risk of bleeding. Intravascular ultrasound guidance helped evolve high pressure stent deployment resulting in lowering of subacute thrombosis with aspirin and ticlopidine instead of aggressive anticoagulation. In this chapter prediction and prevention of stent thrombosis is discussed in detail.