To investigate the relationship between platelet counts within the first 24 hours of veno-arterial extracorporeal membrane oxygenation (V-A ECMO) support and in-hospital mortality in postcardiotomy ECMO patients. Adult patients undergoing postcardiotomy V-A ECMO from 2017 to 2021 were included and divided into survivors and non-survivors. Logistic regression evaluated the association between the first-day platelet counts and in-hospital mortality. Spearman’s correlation assessed the correlations between clinical factors and the platelet hourly % decrease within 24 hours of ECMO support. The study included 72 patients, with an in-hospital mortality of 51.4%. For every 10 ×109/L decrease in the lowest platelet count at 0–24, 0–12, and 12–24 hours of ECMO support, the odds of in-hospital mortality increased by 21.7% (adjusted odds ratios [aOR], 1.217; 95% confidence intervals [CI], 1.045–1.358), 20.6% (aOR, 1.206; 95% CI, 1.058–1.332), and 17.4% (aOR, 1.174; 95% CI, 1.034–1.294), respectively. Platelet hourly % decrease was positively correlated with peak lactate, alanine aminotransferase, D-dimer, fibrinogen degradation products, and ECMO flow rate variation. In postcardiotomy V-A ECMO patients, platelet counts within the first 24 hours of ECMO support are independently associated with higher in-hospital mortality. Potential factors related to decreasing rate of platelet count included thrombosis, ECMO flow fluctuation, tissue ischemia, and hypoxia.
