Heparin-induced thrombocytopenia in patients receiving mechanical circulatory support.
OBJECTIVE
Patients receiving mechanical circulatory support are at risk for the development of heparin-induced thrombocytopenia due to the prolonged postoperative use of heparin. We evaluated their antibody status and outcome.


METHODS
Between 2003 and 2004, 115 patients received mechanical circulatory support for more than 5 days. Blood samples from postoperative day 7 were retrospectively analyzed for anti-platelet factor 4/heparin antibodies and heparin-induced platelet activation.


RESULTS
Overall, 12 (10.6%) patients had heparin-induced thrombocytopenia as defined by in vitro platelet activation, 28 (24.8%) had nonactivating antibodies, and 73 (64.6%) were classified as negative for antibodies. Patients positive for heparin-induced thrombocytopenia had the highest levels of anti-platelet factor 4/heparin immunoglobulin G antibodies. Freedom from thromboembolism was 33%, 33%, and 16% at 1, 3, and 6 months for positive patients, 77%, 68%, and 55% for negative patients (P < .001), and 70%, 53%, and 53% for patients with nonactivating antibodies (P = .068), respectively. The relative risk for thromboembolism in antibody positive patients peaked in the first month of support (odds ratio 7.46, P = .002). Independent risk factors for thromboembolic events included higher anti-platelet factor 4/heparin antibody titers, female gender, and higher fibrinogen levels.


CONCLUSIONS
Heparin-induced thrombocytopenia was more prevalent in patients receiving mechanical circulatory support than in other cardiac patients. Frequent antibody screening is recommended due to the increased risk of thromboembolism. Heparin alternatives should be subjected to clinical trials in these high-risk patients.
Schenk
Soren
S
Thoracic and Cardiovascular Surgery, Heart Center North Rhine-Westphalia, Ruhr-Universität Bochum, Bad Oeynhausen, Germany.
El-Banayosy
Aly
A
Prohaska
Wolfgang
W
Arusoglu
Latif
L
Morshuis
Michiel
M
Koester-Eiserfunke
Wilhelm
W
Kizner
Lukasz
L
Murray
Edward
E
Eichler
Petra
P
Koerfer
Reiner
R
Greinacher
Andreas
A
D000906:Antibodies / Q000097:blood; D000925:Anticoagulants / Q000009:adverse effects* / Q000276:immunology; D005260:Female; D006353:Heart-Assist Devices; D006493:Heparin / Q000009:adverse effects* / Q000276:immunology; D006801:Humans; D008297:Male; D010978:Platelet Factor 4 / Q000276:immunology; D012189:Retrospective Studies; D013921:Thrombocytopenia / Q000139:chemically induced* / Q000453:epidemiology
D000906:Antibodies; D000925:Anticoagulants; D010978:Platelet Factor 4; D006493:Heparin