Congenitally Corrected Transposition of the Great Arteries Recommendations for Congenitally Corrected Transposition of the Great Arteries Referenced studies that support recommendations are summarized in Online Data Supplement 47. COR LOE Recommendations Diagnostic IIa C-LD CMR is reasonable in adults with CCTGA to determine systemic RV dimensions and Therapeutic I B-NR Tricuspid valve replacement is recommended for symptomatic adults with CCTGA and severe TR, and preserved or mildly depressed systemic ventricular function.S4.4.1.4-3,S4.4.1.4-4 IIa C-LD Tricuspid valve replacement is reasonable for asymptomatic adults with CCTGA and severe TR with dilation or mild dysfunction of the systemic ventricle.S4.4.1.4-3 IIb B-NR Conduit intervention/replacement may be considered for adults with CCTGA and symptomatic subpulmonary left ventricle to- PA conduit dysfunction, recognizing that unloading the subpulmonary ventricle may have a detrimental impact on systemic atrioventricular valve function.S4.4.1.4-5 Synopsis The clinical course of adults with CCTGA often de- pends on the presence and severity of associated car- which will often have required pediatric intervention. Rarely, CCTGA may be first diag- nosed in adulthood, particularly if patients do not have associated cardiac lesions. Conduction abnormalities are common, and the prevalence of spontaneous com- plete heart block increases with age.S4.4.1.4-7,S4.4.1.4-8 PS, ASD, and VSD are common. Seventy percent to 90% of patients with CCTGA have a dysplastic or Ebstein- like malformation of the tricuspid valve. This anatomi- cally abnormal systemic atrioventricular valve is at risk of progressive TR, which is an independent predictor of death in CCTGA.S4.4.1.4-4,S4.4.1.4-9 The systematic review report, Medical Therapy for Systemic Right Ventricles: A Systematic Review (Part 1) for the 2018 AHA/ACC Guideline for the Manage- ment of Adults With Congenital Heart Disease. S4.4.1.4-10 addressed the role of medical therapies for manage- ment of functional deterioration in systemic RVsS4.4.1.4- (see additional details in Section 3.17). 