Significantly lower incidence of early definite stent thrombosis of drug-eluting stents after unrestricted use in Japan using ticlopidine compared to western countries using clopidogrel: A retrospective comparison with western mega-studies

SummaryBackground and objectivesThe incidence of definite stent thrombosis (ST) after use of drug-eluting stents (DES), as defined by the Academic Research Consortium, is known to be lower in Japan than in western countries. However, a statistical difference in the incidence of early definite ST (EDST) associated with the unrestricted use of DES has not yet been documented. Therefore, the incidence of EDST in our Japanese institute after unrestricted use of DES was retrospectively compared with those reported in western mega-studies.Methods and resultsDuring the 40 months from August 2004 to November 2007 (before approval of clopidogrel in Japan), DES were implanted in 3605 lesions in 1885 patients in our institute; lesion- and patient-associated percentages of DES use were 95.2% and 94.7%, respectively. Mean stent length per lesion was 33.2 mm, emergent procedures and ST-elevation myocardial infarctions made up 33.7% and 16.4% of the procedures, respectively, intravascular ultrasonography was used 96.0% of the time, a distal protection device for acute coronary syndrome was used 68.7% of the time, and the mean maximum inflation pressure was 19.5 atm. EDST was observed in five lesions (0.139%) in four patients (0.212%). The incidence of patient-associated EDST at our center was significantly lower than in four western mega-studies (0.736%, 66 of 8970 patients; 0.634%, 149 of 23,500; 0.595%, 52 of 8402; 0.997%, 20 of 2006) (p < 0.05, <0.01, <0.05, <0.01, respectively, using a χ2-test).ConclusionDue to differences in procedural approaches in Japan, the incidence of EDST after unrestricted use of DES was significantly lower than in western countries.