Evaluation of Right Ventricular Outflow Tract Stenting as Palliative Treatment in Severely Cyanotic Tetralogy of Fallot: A Systematic Review and Meta-Analysis of Observational Studies.

Background: Tetralogy of Fallot (ToF) is a cardiac malformation that accounts for up to 1/10 of all congenital diseases. Although surgical repair serves as a treatment of choice, it cannot be performed unless weight and anatomical key factors are favorable. The stenting of the right ventricular outflow tract (RVOT) has become an alternative palliative procedure for ToF as an option to alleviate infundibular obstruction with minimal invasion. Methods: A literature search was conducted through 7 databases, followed by the screening and independent assessment of 6 final studies, using the Newcastle-Ottawa Quality Assessment Scale (NOS). Analysis was then conducted using inverse variance analysis, and cumulative data were presented with forest and funnel plots. Results: Studied patients were referred for RVOT stenting due to the marked obstruction of the pulmonary blood flow, a low birth weight, or a small pulmonary artery size. The analysis revealed a significant increase in O₂ saturation (mean difference [MD=18%; 13-23.78). The same trend was observed concerning an increase in the Nakata index (MD=54.59; 10.05-99.14), the right pulmonary artery diameter (MD=2.28; 1.20-3.36), and the left pulmonary artery diameter (MD=1.77; 0.22-3.32). Several complications were found, including tricuspid regurgitation and frequent premature beats. Conclusion: RVOT stenting is considered a feasible palliative treatment for ToF, with its high effectiveness in improving patients' condition, especially their pulmonary flow. While complications are scarce, several conditions should be noted, particularly for fatal complications. Finally, this study has limitations as catheterization details in studies and diverse infants' conditions may have caused potential bias.