Impact of preoperative thrombocytopenia on the outcome after coronary artery bypass grafting

The impact of thrombocytopenia on postoperative bleeding and other major adverse events after cardiac surgery is unclear. This issue was investigated in a series of patients who underwent isolated coronary artery bypass grafting (CABG) from the prospective, multicenter E-CABG registry. Preoperative thrombocytopenia was defined as preoperative platelet count <150 × 109/L and it was considered moderate-severe when preoperative platelet count was <100 × 109/L. Multilevel mixed-effects regression analysis was performed to adjust the effect of thrombocytopenia on outcomes for baseline and operative covariates as well as for interinstitutional differences in patient-blood management. Among 7189 patients included in this analysis, 599 (8.3%) had preoperative thrombocytopenia. Patient with preoperative thrombocytopenia had an increased chest drainage output at 12 h (mean, 519 vs. 456 mL, adjusted coeff. 39, 95%CI 18–60) and rates of severe-massive bleeding (Universal Definition of Perioperative Bleeding (UDPB) severity grades 3–4: 12.7% vs. 8.1%, adjusted OR 1.47, 95%CI 1.11–1.93; E-CABG bleeding severity grades 2–3: 10.4% vs. 6.1%, adjusted OR 1.78, 95%CI 1.30–2.43). Thrombocytopenia was associated with an increased risk of hospital/30-day death (3.2% vs. 1.9%, adjusted OR 2.02, 95%CI 1.20–3.42), 1-year death (5.7% vs. 3.4%, adjusted HR 1.68, 95%CI 1.16–2.44), deep sternal wound infection (3.5% vs. 2.4%, adjusted OR 1.65, 95%CI 1.02–2.66), acute kidney injury (28.1% vs. 22.2%, OR 1.45, 1.18–1.78), and prolonged stay in the intensive care unit (mean, 3.6 vs 2.8 days, adjusted coeff. 0.74, 95%CI 0.40–1.09). Similar results were observed in a subset of patients with moderate-severe thrombocytopenia (51 patients, 0.7%). In particular, these patients had a markedly higher rate of acute kidney injury (40%, adjusted OR, 1.94, 95%CI 1.05–3.57), resternotomy for bleeding (7.8%, adjusted OR 3.49, 95%CI 1.20–10.21), and severe-massive bleeding (UDPB severity grades 3–4: 23.5%, adjusted OR 3.08, 95%CI 1.52–6.22; E-CABG bleeding severity grades 2–3: 23.5%, adjusted OR 4.43, 95%CI 2.15–9.15) compared to patients with normal preoperative platelet count. Mild preoperative thrombocytopenia is associated with increased risk of severe-massive bleeding, mortality, and other major adverse events after CABG. Such risks are markedly increased in patients with moderate-severe preoperative thrombocytopenia.