Background  Late stent malapposition was frequently observed after DES implantation, which has been associated with the occurrence of late stent thrombosis due to poor neointimal coverage. This study was designed to evaluate the frequency of late stent malapposition at least 1 year after different DESs implantation by optical coherence tomography (OCT).
Methods  Angiographic and OCT examinations were given to 68 patients who had received total 126 various DESs implantation for at least 1 year to detect late stent malapposition. Malapposed strut distance (MSD), malapposed strut area (MSA), reference lumen area (RLA) and reference stent area (RSA) were checked with off-line OCT analysis.
Results  Totally 26 Cypher Select stents, 15 Taxus Liberte stents, 51 Partner stents and 34 Firebird I stents were examined. Among 68 patients who underwent DES implantation, 7 patients (10.3%) had late malapposition. Average RSA , MSA and MSD were (7.9±2.8) mm²,(2.0±1.6) mm² and (590±270) µm respectively. According to the MSA/RSA ratio, 4 patients had slight malapposition, 2 patients had moderate malapposition and 1 patient had severe malapposition.
Conclusions   Late stent malapposition is detected frequently after implantation of DES, but if this predisposes to late stent thrombosis and requires any specific therapy needs to be further elucidated.