Reversible clopidogrel resistance due to right ventricular myocardial infarction: risk factor of recurrent stent thrombosis?

A 63-year-old male Patient was admitted to the intensive care unit due to acute inferior myocardial infarction with right ventricular dysfunction. He received a loading dose of clopidogrel (600 mg) and aspirin (500 mg) and was immediately revascularized by reopening of the proximal right coronary artery (RCA) and implantation of a bare metal stent. After primary successful intervention the patient suffered from thoracic pain on day 5 of admission. The ECG indicated reinfarction. The proximal RCA was again re-opened by PTCA alone. The following day the patient suffered again from thoracic pain with ST-elevation in the inferior leads, this time complicated by additional total AV-blockade. The angiography showed another time a thrombotic occlusion of the initially implanted stent. He received another intervention with implantation of additional two bare-metal stents, an aortic counter-pulsation and a temporary two-chamber pace maker. Tirofiban was administered for 24 h and the IABP was withdrawn after 60 h. The patient was discharged on Aspirin 300 mg/d, Clopidogrel 150 mg/d and Enoxaparin 40 mg/d. Six weeks later the patient demonstrated an improved right ventricular function (TAPSE 18 mm), liver enzymes were normal, and inhibition of platelet aggregation by clopidogrel (150 mg/d) was sufficient. In conclusion this implies that the reversible "clopidogrel-resistance" might have been due to congestion and reduced metabolism due to right ventricular infarction.