Summary
Thrombocytopenia as well as anti-platelet factor 4/heparin (PF4/H) antibodies are
common in cardiac surgery patients and those treated in the intensive care unit. In
contrast, heparin-induced thrombocytopenia (HIT) is uncommon in these populations
(∼1 % and ∼0.5 %, respectively). A stepwise approach where testing for anti-PF4/H
antibodies is performed only in patients with typical clinical symptoms of HIT improves
diagnostic specificity of the laboratory assays without losing sensitivity, thereby
helping to avoid overdiagnosis and resulting HIT overtreatment. Short-term re-exposure
to heparin, especially given intraoperatively for cardiovascular surgery, is a reasonable
therapeutic option in patients with a history of HIT who subsequently test negative
for HIT antibodies. Organ failure(s), enhanced bleeding risks, and other characteristics
require special considerations regarding non-heparin anticoagulation: Argatroban is
the alternative anticoagulant with pharmacokinetics independent of renal function,
but it has a prolonged half-life in case of impaired liver function. For bivalirudin,
protocols during cardiopulmonary bypass surgery are established, and it is suitable
for patients with liver insufficiency. A major issue of direct thrombin inhibitors
are false high activated partial thromboplastin time values in patients with comorbidities
affecting prothrombin, which can result in systematic underdosing of the drugs. This
is not the case for danaparoid and fondaparinux, which can be monitored by anti-factor
Xa assays, but have long half-lives and no suitable antidote. This review includes
also information on management of on- and off-pump cardiac surgery, ventricular assist
devices, percutaneous interventions, continuous renal replacement therapy, and extracorporeal
membrane oxygenation in patients with HIT.
Keywords
Heparin-induced thrombocytopenia - intensive care unit - cardiac surgery