Late coronary stent thrombosis.

: Coronary stent thromboses are characterized as early, if they occur within one month of the index PCI. Late stent thromboses (LST) have an occurrence after one month. Both early and late stent thromboses are a major concern in PCI, because of their clinical presentation as acute myocardial infarction and sudden cardiac death. Early stent thromboses are seen following implantation with bare metal (BMS) and drug eluting (DES) stents. Late occurring stent thromboses (LST) are rare but usually severe events and primarily seen after DES implantation. A number of pathogenetic mechanisms seem to be operating and there will probably be major differences between different types DES and the risk of LST. While early stent thrombosis is primarily related to stent implantation techniques, lesion characteristics and the effect of double platelet therapy, there is emerging evidence that very late stent thrombosis, occurring more than one year after the implantation may be caused by local tissue reaction to the polymers of sirolimus and paclitaxel eluting stents. It is likely that the use of new generations DES with tissue friendly polymers or bioabsorbable polymers will reduce the risk of late stent thrombosis.