Heart Beat: Clots can form in stents years after placement
Wire-mesh stents were invented to prop open heart arteries that balloon angioplasty had just cleared of cholesterol-laden plaque. Coating them with drugs helped fix an early problem: cells from the artery wall surrounding the stent sometimes grew over and around the stent and clogged the space through which blood flows.
But without a protective coating of artery-wall cells, a stent is an attractive surface for blood-clot formation. If such a clot is large enough, it can trigger a heart attack. This is called stent thrombosis.