Late and very late coronary stent thrombosis: Intravascular ultrasound findings and associations with antiplatelet therapy

Late and very-late stent occlusion remains a serious complication of coronary stenting. Despite their high anti-restenotic efficacy, drug-eluting stents (DES) have been associated to more late-thrombosis as compared to bare-metal stents (BMS). The aim of this study is to analyze the clinical presentation, angiographic, and intravascular ultrasound (IVUS) findings in patients with late or very late stent thrombosis and the relationship with the antiplatelet regimen.Between January 2007 and December 2011, 34 consecutive patients with clinical syndromes compatible with late or very-late stent occlusion were studied with IVUS during emergency catheterization; 25 had DES and 9 had BMS. Thrombotic total occlusion was more common in DES (16 = 64%) than BMS patients (2 = 22%; P = 0.02) and ST-segment elevation myocardial infarction was the predominant clinical presentation in the former group (60% compared to 22%; P = 0.05). The time elapsed between implantation and failure was much longer in DES patients: 33 ± 22 versus 17 ± 14 months for BMS; P = 0.05. IVUS analysis showed a higher incidence of incomplete stent apposition (ISA) in the DES group compared to the BMS group (56% vs. 11%; P = 0.005) and in-stent plaque rupture was the most common finding in the BMS group (78%). In DES group, ISA was found more frequently in patients still under dual antiplatelet therapy (71%).Very late DES failure often causes ST-elevation myocardial infarction; these very late events may not correlate with the interruption of antiplatelet therapy. Severe, late acquired ISA belongs to DES and is frequently observed in patients with very late DES thrombosis.