Intravascular stents do not cause microangiopathic hemolysis or thromboticmicroangiopathy

An increased incidence of TTP has been noted among patients receiving intra vascular stents to improve patency in diseased coronary, renal, and periphe ral arteries. Placement of transjugular intrahepatic porto-systemic shunt s tents is often associated with subsequent development of severe hemolysis. We have propsectively studied the development of microangiopathic hemolysis or TTP in patients undergoing intravascular stent placement for peripheral vascular or renal artery disease. Hemolysis was evaluated both before and after stent placement by measuring complete blood count, total bilirubin, l actate dehydrogenase (LDH), haptoglobin and reticulocyte count, and examini ng peripheral blood alms of all patients. Coagulation parameters, blood ure a nitrogen and creatinine were measured to exclude disseminated intravascul ar coagulation or thrombotic thrombocytopenic purpura as a potential cause of hemolysis. Seventeen patients (median age 69 years) were evaluated. One patient was on ticlopidine. Mean hematocrit fell from 41.8% pre-stenting to 35.5% post-stenting (P = 0.003) but without significant change in reticulo cyte count (1.7 vs. 1.6%, P = 0.605), LDH (546 vs. 560 IU/l; P = 0.836), bi lirubin (0.62 vs. 0.63 mg/dl; P = 1.0), or haptoglobin (183 vs. 158 mg/dl; P = 0.083). Thus, this drop in hematocrit could not be attributed to hemoly sis. Peripheral blood films revealed fewer than 1% schistocytes before and after stent placement in all cases. Absence of significant changes in mean platelet count (240 vs. 210 x 10(9)/L; P = 0.088), fibrinogen (385 vs. 378 mg/dl; P = 0.789), BUN (24.5 vs. 16.8; P = 0.079), and creatinine (1.38 vs. 1.24; P = 0.757) argue against development of TTP or DIC resulting from st ent placement. No patient developed new renal impairment, a neurological sy ndrome, or unexplained fever after stent placement. At a mean of 6 weeks fo llow-up after stent placement, patients have not developed signs of hemolyt ic anemia or worsening renal function. Our findings argue against a primary risk of microangiopathic hemolytic anemia or TTP due to intravascular sten ts in patients not receiving ticlopidine. (C) 1999 Wiley-Liss, Inc.