**4.4 Heparin-induced thrombocytopenia**

Thrombocytopenia is a devastating complication in patients on VA-ECMO support. The etiology of platelet reduction in ECMO is still ambiguous. HIT has been considered one of the causative mechanisms. Current literature has very little to offer in this area. The incidence and mortality secondary to HIT in VA-ECMO patients is very poorly represented. In a recent retrospective study on VA-ECMO patients hospitalized for >3 days with high clinical suspicion of HIT and positive anti-PF4/heparin antibodies, the prevalence of HIT in patients on VA-ECMO support was estimated as 0.36%. Mortality rate was noted as 33.3%, which was not statistically different from the mortality observed in patients on VA-ECMO support without HIT [26]. HIT is a complication that appears to have a low prevalence; its effects are devastating if untreated. Bivalirudin and argatroban have been used to successfully treat this condition in VA-ECMO patients in small studies [27–29]. Further investigations in larger populations are required in this patient population for standardized regimens to be incorporated into the guidelines.
