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.

BACKGROUND

In patients with congenitally corrected transposition of the great arteries (ccTGA), assessment of readiness for the double switch operation (DSO) after pulmonary arterial band (PAB) placement involves cardiac magnetic resonance imaging (cMRI) to measure left ventricular ejection fraction (LVEF) and mass and cardiac catheterization (catheterization) to assess the ratio of left ventricular to right ventricular pressure (LV:RVp). The aims of this study were to describe the relationships between echocardiographic and catheterization and cMRI measures of readiness for DSO and to develop risk factors for left ventricular (LV) dysfunction after DSO on the basis of echocardiographic measures of ventricular-arterial coupling (VAC).

METHODS

Patients with ccTGA undergoing LV retraining at a DSO referral center were reviewed. LVEF measured by echocardiography was compared with that measured by cMRI, and LV:RVp measured by echocardiography was compared with that measured by catheterization using Bland-Altman analysis. The relationship between preoperative VAC markers and postoperative echocardiography was analyzed using ventricular end-systolic elastance (EES) and a novel marker consisting of the product of LVEF and LV:RVp (EFPR).

RESULTS

Thirty-one patients with 56 evaluations for DSO were included, 24 of whom underwent DSO. Echocardiographic LVEF correlated well with cMRI LVEF (r = 0.79), and Bland-Altman analysis slightly overestimated cMRI LVEF (mean difference, +3%). Echocardiographic LVEF had a moderate ability to identify normal cMRI LVEF (area under the curve, 0.80) and at an optimal cut point of echocardiographic LVEF threshold of 61%, there was 71% sensitivity and 76% specificity to detect cMRI LVEF ≥ 55%. Echocardiographic LV:RVp correlated well with LV/RVp by catheterization (r = 0.77) and slightly underestimated the catheterization value (mean difference, -0.11). Echocardiographic LV:RVp had a good ability to identify adequate LV:RVp by catheterization (area under the curve, 0.95) and at an optimal echocardiography cut point of 0.75 had 100% sensitivity and 85% specificity to detect a catheterization LV:RVp >0.9. Echocardiography-based criteria for DSO readiness (echocardiographic LVEF 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 LVEF of 55% and catheterization LV:RVp of 0.9). EES and EFPR correlated with post-DSO LVEF (ρ = 0.72 and ρ = 0.60, respectively). EFPR of 0.51 demonstrated 78% sensitivity and 100% specificity for post-DSO LV dysfunction (LVEF < 55%). Age at first PAB also strongly correlated with post-DSO LVEF (ρ = 0.75). No patient with first PAB at <1 year of age exhibited post-DSO LV dysfunction.

CONCLUSIONS

Echocardiographic measures of LVEF and LV:RVp are reliable indicators of reference standard modalities and can guide management during retraining. The preoperative VAC markers EES and EFPR may be useful markers of post-DSO LV dysfunction. Values of echocardiographic LV:RVp >0.75 are likely to meet pressure-generation criteria for DSO and should be considered for referral to catheterization and cMRI evaluation for DSO. PAB placement before 1 year of life may optimize LV outcomes in patients considered for DSO.