Outcomes after heparin-induced thrombocytopenia in patients with Propaten vascular grafts.
BACKGROUND
Heparin-induced thrombocytopenia (HIT) can result in a life- or limb-threatening condition that can be reversed with early detection and prompt discontinuation of systemic heparin. The advent of heparin-bonded grafts may introduce a new level of complexity in some patients with a suspected diagnosis of HIT. This review evaluates the outcomes of patients who received the Gore Propaten vascular graft with a subsequent suspicion of HIT.


METHODS
This is a retrospective analysis of cases with suspected type II HIT after implant of the Propaten vascular graft that were reported to W.L. Gore & Associates. Data reviewed included clinical studies, including physician-sponsored studies, both inside and outside the United States; published literature; and Gore's product surveillance records.


RESULTS
Overall, as of June 2011, there have been 27 cases (27 patients and 30 vascular grafts) of suspected HIT after graft implant. Of these 27 patients, 18 were tested for HIT antibodies (enzyme-linked immunosorbent assay, heparin-induced platelet activation test, serotonin release assay, drug-induced platelet activation test, platelet aggregation test, an HIT panel, or an unknown HIT test), with a positive test result in 17 of the 18 cases. In 5 of the 18 cases, patients were tested with two distinct HIT assays, resulting in one positive and one negative test. Among patients with available data, the mean preoperative heparin dose was 4850 ± 1634 U, and four patients had a postoperative heparin drip. The mean preoperative platelet count was 227,000 ± 71,616. Mean platelet count at time of diagnosis of HIT was 53,429 ± 36,832. For the majority of those patients known to have had heparin discontinued once HIT was suspected, Argatroban was the anticoagulant of choice. Sixteen patients had grafts that remained implanted and in circulation, eight patients had grafts that were explanted, two patients had grafts that were ligated in situ, and the outcome was unknown for one patient. Among the 16 patients with grafts remaining in circulation, four grafts required thrombectomy for occlusion. Two patients died, one other patient had a remote thrombotic event, and the remaining patients had no reported adverse events. Among the 10 patients with graft removal or ligation, six had a graft occlusion, four required an amputation, and two died. Among the cases in which the recovery of platelet count was reported after systemic heparin was discontinued, the majority were cases in which the grafts were left in circulation.


CONCLUSIONS
Analysis of the cases of suspected HIT in patients with implanted Propaten vascular grafts reveals that the HIT observed appears to be related to the systemic administration of heparin. After discontinuation of systemic heparin, platelet counts normalized in the presence of patent Propaten vascular grafts. Hence, based on current data, our recommendation would be to tailor treatment to individual patients. Functioning grafts in patients with or without thrombotic events and return of platelet count to normal values may not require grafts to be explanted in the presence of HIT.
Natural Molecular Testing Corporation, Walnut Creek, CA 94596, USA. kasi@naturalmolecular.com
Karthikeshwar
K
Kasirajan
D000671:Amputation, Surgical; D000925:Anticoagulants / Q000008:administration & dosage / Q000009:adverse effects*; D001120:Arginine / Q000031:analogs & derivatives; D001807:Blood Vessel Prosthesis; D019917:Blood Vessel Prosthesis Implantation / Q000009:adverse effects / Q000295:instrumentation* / Q000401:mortality; D002140:California; D020099:Coated Materials, Biocompatible; D020878:Device Removal; D057915:Drug Substitution; D006083:Graft Occlusion, Vascular / Q000209:etiology / Q000517:prevention & control*; D006493:Heparin / Q000008:administration & dosage / Q000009:adverse effects*; D006801:Humans; D008026:Ligation; D010875:Pipecolic Acids / Q000008:administration & dosage; D011474:Prosthesis Design; D012086:Reoperation; D018570:Risk Assessment; D012307:Risk Factors; D013449:Sulfonamides; D017131:Thrombectomy; D013921:Thrombocytopenia / Q000139:chemically induced* / Q000175:diagnosis / Q000401:mortality / Q000628:therapy; D016896:Treatment Outcome
D000925:Anticoagulants; D020099:Coated Materials, Biocompatible; D010875:Pipecolic Acids; D013449:Sulfonamides; D006493:Heparin; D001120:Arginine; C031942:argatroban