Modified Blalock-Taussig-Thomas shunt blockage and mortality: A systematic review and meta-analysis

In this systematic review and meta-analysis, we discuss the estimated of global incidence, shunt related-mortality risk and factors associated with shunt blockage after modified Blalock-Taussig-Thomas (mBTT) procedure.

A systematic review and meta-analysis were conducted using PubMed, ScienceDirect, and EMBASE up to February 2024. The primary outcomes were the incidence and mortality risk associated with shunt blockage. Additional outcomes included study characteristics, surgical factors, and coagulation profiles. Single and two-group proportional meta-analyses were performed.

A total of 25 studies involving 2,677 patients were included. The global incidence of shunt blockage was 7% (95% confidence interval [CI]: 0.05 to 0.10) with high heterogeneity (I² =81%; p<0.01). In 15 studies eligible for mortality analysis, patients with shunt blockage had significantly higher odds of death (odds ratio [OR]=5.04; 95% CI: 2.69 to 9.44) with low heterogeneity (I² =3%; p=0.41). Shunt size alone was not a significant predictor of blockage. However, patients with shunt blockage exhibited significantly lower partial thromboplastin time and activated partial thromboplastin time values, suggesting coagulation abnormalities. No significant difference was found in platelet counts.

Shunt blockage is a critical complication following mBTT shunt, significantly increasing mortality risk. While shunt size is not independently predictive, multiple factors, including patient weight, underlying pathology, coagulation profile, surgical factors, and shunt size-to-weight ratio, may contribute to thrombosis risk and warrant further investigation.