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

Abstract

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 Tirofiban was administered for 24 h and the IABP was withdrawn after 60 h. The patient was discharged on Aspirin 300 mg/d, Clopidogrel 150 mg/d and Enoxaparin 40 mg/d. Six weeks later the patient demonstrated an improved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.

Individualized antiplatelet therapy

“…Besides, decreased drug metabolization due to haemodynamic disturbances or cardiogenic shock in the context of ACS can lead to decreased drug efficacy (32,33). Left ventricular function has been shown to affect clopidogrel responsiveness (28,34).…”