Late acquired incomplete stent apposition: incidence, mechanisms and clinical implications

Late acquired incomplete stent apposition (LAISA) is an intravascular ultrasound (IVUS) finding that has been associated with late and particularly very late drug-eluting stent (DES) thrombosis. The underlying mechanism appears to be regional positive remodelling due to inflammation necrosis related with DES components. Incidence is higher for DES (10-12%) compared to bare-metal stents (4%) in native vessels, with no data in saphenous vein grafts. Large LAISA has been found in 60-77% of cases with DES late thrombosis studied with IVUS. However, clinical follow-up studies of cases with routinely detected LAISA either do not show a relationship to thrombosis or only reflect a trend, although when taken as a whole, that trend is significant. There is no evidence that correction of LAISA should be a target for secondary or repeated revascularisation. Benefits and risks of LAISA correction are unknown.