Echocardiographic Predictors of Readiness for Double Switch Operation and Postoperative Ejection Fraction in Patients with Congenitally Corrected Transposition of the Great Arteries Undergoing Left Ventricular Retraining

Abstract

BackgroundIn patients with congenitally corrected transposition of the great arteries (ccTGA), assessment of readiness for double switch operation (DSO) after pulmonary arterial band (PAB) placement involves cardiac MRI (cMRI) to measure LV ejection fraction (EF) and mass and cardiac catheterization (cath) to assess LV:RV pressure ratio (LV:RVp). We described the relationships between echocardiographic and cath/cMRI measures of readiness for DSO, and developed risk factors for LV dysfunction after DSO based on echocardiographic measures of ventricular arterial coupling (VAC). MethodsWe reviewed patients with ccTGA undergoing LV retraining at a DSO referral center. We compared EF measured by echo to cMRI, and LV:RVp measured by echo to cath with Bland-Altman (BA) analysis. We analyzed the relationship between preoperative VAC markers and postoperative echocardiogram using end-systolic elastance (EES), and a novel marker consisting of the product of EF and the LV:RVp (EFPR). ResultsWe included 31 patients with 56 evaluations for DSO, 24 of which underwent DSO. Echo EF correlated well with cMRI (r= 0.79), and BA slightly overestimated cMRI (mean difference +3%). Echo EF had moderate ability to identify normal cMRI EF (AUC of 0.80) and at optimal cutpoint of echo EF threshold of 61%, there was 71% sensitivity and 76% specificity to detect cMRI LVEF >=55%. Echo LV:RVp correlated well with cath (r=0.77) and slightly underestimated cath (mean difference of -0.11). Echo LV:RVp had good ability to identify adequate LV:RVp by cath (AUC=0.95) and at optimal echo cutpoint of 0.75 had 100% Sensitivity and 85% specificity to detect a catheterization LV:RVp above 0.9. Echo-based criteria for DSO readiness (echo EF of 61% and LV:RVp of 0.75) demonstrated specificity of 97% and positive predictive value of 96% for published criteria of DSO readiness (cMRI EF of 55% and cath LV:RVp of 0.9). EES and EFPR correlated with post DSO EF (rho= 0.72 and 0.60). EFPR of 0.51 demonstrated 78% sensitivity and 100% specificity for post DSO LV dysfunction (EF < 55%). Age at first PAB also strongly correlated with post DSO EF (rho=0.75). No patient with first PAB under age 1 years exhibited post DSO LV dysfunction. ConclusionsEchocardiographic measures of EF and LV:RVp are reliable indicators of reference standard modalities, and can guide management during retraining. Preoperative VAC markers EES and EFPR may be useful markers of post-DSO LV dysfunction. Echo LV:RVp > 0.75 are likely to meet pressure-generation criteria for DSO and should be considered for referral for cath and cMRI evaluation for DSO. PAB placement before 1 year of life may optimize LV outcomes in patients considered for DSO.