Risk Factors for Thrombus Formation at Stage 2 Palliation and Its Effect on Long-Term Outcome in Patients With Univentricular Heart

Thrombus formation is a feared complication following bidirectional cavopulmonary shunt (BCPS). We aimed to investigate the effect of thrombus formation on outcome. BCPS was performed in 525 patients at our center between 1998 and 2018. The impacts of thrombus formation on survival and probability of Fontan completion were analyzed, and risk factors for thrombus formation were examined. Thrombus formation occurred in 30 patients (5.7%). Compared with the remaining 495 patients, there was no significant difference in the median age at BCPS (4.9 vs 4.7 months; P = 0.587). However, unbalanced atrioventricular septal defects (17 vs 5%; P = 0.008) and preoperative ventricular dysfunction (23.3 vs 8%; P = 0.004) were more frequent in patients who developed a thrombus. Thrombolytic therapy was performed in all patients and surgical thrombus removal was required in 13 patients. In-hospital mortality was higher in patients with thrombus (30.0 vs 2.2%; P < 0.001). Of 505 hospital survivors, an estimated survival at 1 year after hospital discharge following BCPS was 84.4% (95% CI, 76.1–92.7%) in patients with thrombus and 96.8% (95% CI, 96.0–97.6%) in those without (P < 0.001). Cumulative incidence of Fontan completion at 3 years after BCPS was 52.8% (95% CI, 30.3–75.2%) in patients with thrombus and 90.1% (95% CI, 87.2–92.9%) in those without (P = 0.004). Higher left atrial pressure (OR = 1.165; P = 0.029) and longer cardiopulmonary bypass time (OR = 1.013, P = 0.001) at BCPS were independent risk factors for thrombus formation after BCPS. Thrombus formation after BCPS poses a significant risk for survival and Fontan completion. Preoperative higher left atrial pressure and longer cardiopulmonary bypass time are significant risk factors.