stent thrombosis is a rare but fatal complication of drug eluting stent ( des ) .
although dual antiplatelet therapy with aspirin and clopidogrel significantly reduced the occurrence of stent thrombosis , late stent thrombosis still occurs ; many other factors could be attributable to the occurrence.1)2 ) of these , clopidogrel resistance is regarded as one of the main reasons for the occurrence of des thrombosis .
therefore , new antiplatelet agents have been developed recently and are reported to have better outcomes.3 ) we report a case of recurrent des thrombosis with clopidogrel resistance successfully rescued by prasugrel .
a 58-year - old non - smoker male who had no specific medical history visited the emergency room with typical angina on april 2006 .
percutaneous coronary intervention with 3.023 mm - sized sirolimus - eluting stent ( cypher ; cordis corp .
, miami lakes , fl , usa ) at the mid portion of the left anterior descending artery ( m - lad ) and 2.7518 mm - sized sirolimus - eluting stent at the distal portion of left circumflex artery ( d - lcx ) were performed ( fig .
he received triple antiplatelet drugs ( aspirin 100 mg daily , clopidogrel 75 mg daily , cilostazol 100 mg twice daily ) .
after that , cilostazol and clopidogrel were discontinued on july 2006 ( 3-month use ) and on june 2009 ( 37-month use ) , respectively .
three weeks after clopidogrel discontinuation , he felt typical angina and was diagnosed with non - st - segment - elevated myocardial infarction ( creatine kinase - mb 5.64 ng / ml , troponin - t 0.019 ng / ml ) .
on the coronary angiography , intraluminal thrombi in the distal portion of m - lad stent and totally occluded d - lcx stent were noted ( fig .
percutaneous coronary intervention with 3.020 mm - sized balloon was performed on m - lad and d - lcx stents as well as on the distal portion of lad .
thereafter , triple antiplatelet therapy , including cilostazol 100 mg twice daily , was restarted .
the patient had no further chest pain and cilostazol and clopidogrel were discontinued on march 2010 ( 9-month use ) and on june 2010 ( 12-month use ) , respectively . however , he visited the emergency room again on jan 2011 because of a severe ongoing chest pain .
electrocardiogram showed st elevation ( > 1 mm ) on the anterior ( v 1 - 3 ) lead . emergency coronary angiography was performed and both m - lad and d - lcx stents were totally obstructed on the angiogram ( fig .
thrombus aspiration ( thrombuster ii ; kaneka medix corporation , osaka , japan ) and balloon dilation with 3.015 mm - sized balloon were performed on both m - lad and d - lcx stents ( fig .
2c ) . because of the drop of blood pressure during the procedure ( 80/50 mm hg ) , intraaortic balloon pump ( autocat2 wave - fiber optic ; arrow international inc . ,
reading , pa , usa ) and percutaneous cardiopulmonary support ( capiox ebs ; terumo corporation , tokyo , japan ) were applied .
transthoracic echocardiogram was performed right after the procedures showed a reduced left ventricular ejection fraction of 25% with anterior and anteroseptal wall akinesis .
after that , the patient was stable and all the other devices were removed ; he was sent to the general ward . however , thirteen days post procedure , he experienced a severe resting pain again .
the resting electrocardiogram showed a st segment elevation on v 1 - 6 leads . on the emergency angiogram ,
percutaneous coronary intervention with 3.013 mm - sized balloon was performed on m - lad and d - lcx stents ( fig .
due to suboptimal revascularization flows , 3.030 mm - sized zotarolimus - eluting stent implantation ( endeavor sprint ; medtronic cardio - vascular , minneapolis , ms , usa ) was performed on m - lad . the day before the last event , the platelet function test with verify - now - p2y12 rapid analyzer ( accumetrics inc .
, san diego , ca , usa ) showed inadequate platelet inhibition results { 280 p2y12-receptor reaction units ( pru ) , 14% inhibition}. finally , clopidogrel was switched with prasugrel 10 mg daily followed by a 60 mg loading .
six days later , the platelet function test showed an adequate platelet inhibition ( 9 pru , 98% inhibition ) .
after discharge , cilostazol was discontinued on may 2011 ( 4-month use ) and the platelet function test still showed a good response to the dual antiplatelet with aspirin and prasugrel ( 92 pru , 70% inhibition ) .
after a nine - month follow - up , the coronary angiography showed a patent both in lad and lcx stents .
currently , dual antiplatelet drugs with aspirin and prasugrel were maintained without any chest pain ( 13-month use ) ( fig .
although dual antiplatelet therapy with aspirin and clopidogrel is the standard medication in patients with des implantation , the unmet needs still exist and fatal complication occurs . particularly , clopidogrel resistance , regarded as one of the major factors for stent thrombosis , has been reported to occur in 30 - 40% of patients.4 - 7 ) to overcome clopidogrel resistance , a dose - up of clopidogrel or triple antiplatelet therapy with cilostazol has been recommended .
however , recent clinical trials , such as gravitas ( gauging responsiveness with a verifynow assay - impact on thrombosis and safety ) did not show a better prognosis than the existing standard - dose dual antiplatelet.8 ) although some clinical trial described that triple antiplatelet therapy including cilostazol has a beneficial effect on ischemic complications , there are still many debates.9)10 ) under this situation , new anti - platelet agents give us a new choice . of these ,
prasugrel , which is hydrolysed by esterases into an intermediate precursor and whose activation is not involved with oxidation by the enzyme cyp2c19,11 ) can consistently and rapidly inhibit adp - induced platelet aggregation than clopidogrel.12 ) prasugrel was significantly superior to clopidogrel for the reduction of ischemic events , including stent thrombosis in triton - timi 38 ( trial to assess improvement in therapeutic outcomes by optimizing platelet inhibition with prasugrel - thrombolysis in myocardial infarction ) analysis.3 ) also , some studies reported that prasugrel achieved greater inhibition of platelet aggregation in clopidogrel resistance patients.13 ) our case revealed the recurrent stent thrombosis events despite dual or triple antiplatelet therapy including cilostazol .
in particular , new stent implantation ( endeavor sprint ) at m - lad could make a beneficial contribution for stent thrombosis through the hemodynamic improvement in the present case .
however , d - lcx stent ( cypher ) with balloon - only angioplasty has also shown a good patency in a follow - up angiography .
thus , rescued clopidogrel resistance could be the main reason rather than the hemodynamic improvement .
after the change of antiplatelet into prasugrel , clopidogrel resistance was successfully rescued and no thrombotic event has been observed until now . in conclusion , for the prevention of recurrent des thrombosis , dual antiplatelet with aspirin and prasugrel could be one of the potential options in patients with clopidogrel resistance .
 stent thrombosis is a very serious problem after drug - eluting stent ( des ) implantation even though its incidence is about or less than 1% . 
 as the clopidogrel resistance is expected to play an important role in the occurrence of stent thrombosis , new anti - platelet agents overcoming this issue can give us another choice . 
 we experienced a case of a 58-year - old male with successful prasugrel rescue therapy in a patient with clopidogrel resistance who had recurrent stent thrombosis following des implantation . 