To the Editor: Idiopathic thrombotic thrombocytopenic purpura (TTP) is a lifethreatening disease characterized by thrombocytopenia, microangiopathic hemolytic anemia, fever, neurologic changes, and renal dysfunction and is related to autoantibodies against von Willebrand factor cleaving metalloprotease [1]. Clopidogrel is an antiplatelet drug used to prevent coronary stent thrombosis; however, TTP as its complication has been described [2]. Clopidogrel-associated TTP (CA-TTP) presenting with coronary artery thrombosis is extremely rare. Here, a patient with CA-TTP presenting with coronary artery occlusion is described.
A 66-year-old woman with diabetes mellitus, parathyroidectomy, hypertension, peptic ulcer, anxiety, and depression presented in June 2004 with a subendocardial myocardial infarction. She underwent a percutaneous transluminal coronary angioplasty (PTCA) and stent placement of the left anterior descending (LAD) artery. She was placed on 300 mg clopidogrel (loading dose) followed by 75 mg qd. She remained asymptomatic until August 2004 when she developed unstable angina and was transferred to our hospital for PTCA. Her medications were digoxin, metoprolol, venlafaxine, furosemide, simvastatin, insulin, clopidogrel, and aspirin. Complete blood count revealed WBC 8.6 Â 10 9 /L, hemoglobin 12.5 g/dL, platelet 72 Â 10 9 /L, with normal WBC differential counts. Coronary angiogram showed 90% occlusion of the LAD artery just proximal to the previously placed stent. She underwent PTCA and stent placement of the lesion and was placed on 12-h eptifibatide infusion. The next day, platelet count was 40 Â 10 9 /L. Hematology consultation was obtained. Her physical examination was unremarkable. Blood smear showed anisopoikilocytosis, polychromasia, and schistocytes 2/high-power-field. Other blood tests were as follows: hemoglobin 9.9 g/dL, serum haptoglobin 20 mg/dL (low), reticulocyte 2.7%, lactate dehydrogenase (LDH) 5504 U/L, unconjugated bilirubin 2.0 mg/dL, blood urea nitrogen 54 mg/dL, creatinine 2.9 mg/dL, and normal clotting profile.
CA-TTP was diagnosed based on recent clopidogrel use, coronary artery thrombosis, microangiopathic hemolytic anemia, thrombocytopenia, and renal dysfunction. Clopidogrel was discontinued and she received fresh frozen plasma and daily plasmapheresis (PE). Within 96 h, her platelet count was 148 Â 10 9 /L