To evaluate indications of post-operative cardiac catheterization procedures (POCCPs) after pediatric cardiac surgery and their impact on outcomes.

POCCP is proposed in a variety of situations. Clinical impact of diagnostic POCCPs and transcatheter interventions (TCIs) remain scarcely described.

Non-planned POCCPs performed after congenital heart surgeries and before hospital discharge between January 2013 and July 2019 were reviewed. Hybrid procedures were excluded. Heart defects, illness course, surgeries, and POCCPs were classified. Indications and findings were comprehensively regrouped. Outcomes were analyzed.

Two hundred and seventeen POCCPs were performed on 192 patients (median age 2.3months, weight 4.2kg) on median postoperative-day 8 (IQR 2-20days). Patients had defects of great complexity (79.9%) and a high disease severity index (46.4%). Aristotle's complexity level of surgeries was III (27.6%) and IV (47.4%). POCCPs CRISP category was 4 (39.6%) and 5 (22.6%). POCCPs identified 70 (32.3%) new diagnostic information. POCCPs confirmed 67.1% of suspected diagnoses: anatomical lesions were less likely to be confirmed when compared to physiological anomalies (55.6%<81.7%, P<0.01). Surgically-acquired lesions were less likely confirmed when compared to residual lesions (P<0.01). In confirmed diagnoses, POCCP indicated interventions (74.1%), and changes in medical management (25.9%). Interventions (133 TCIs, 16 redo-surgeries) were successful (97%) and immediate (92.6%). TCIs were unplanned (38.3%) and performed across fresh suture lines (30.1%). Eight significant adverse events were recorded and survival to discharge was 87.5%.

POCCP provides adequate answers for both anatomical and physiological questions in high-risk patients with complicated courses. POCCP guides appropriately subsequent treatment with high efficiency and satisfactory outcomes.