Prevalence and Predictors of Impaired Coronary Flow Velocity Reserve in Adolescents After Arterial Switch Operation

Background/Objectives: We assessed the prevalence of impaired coronary flow velocity reserve (CFVR) and aimed to identify echocardiographic and clinical predictors of coronary microvascular dysfunction in adolescents after neonatal arterial switch operation (ASO). Methods: This single-center, cross-sectional study included patients that underwent neonatal ASO for simple D-transposition of the great arteries (D-TGA) during 1998-2013. All patients were evaluated by echocardiography with global left ventricular strain measurement (GLS) and cardiac catheterization, including coronary angiography. Coronary flow velocity reserve was assessed by transthoracic Doppler echocardiography in the left anterior descending artery (LAD) using adenosine induced hyperemia. Patients were stratified into two groups according to CFVR: group with impaired CFVR (<2.5) and group with normal CFVR (≥2.5). Spearman correlation was used to assess the relationship between CFVR and echocardiographic variables. Binary logistic regression was used to determine independent predictors of impaired CFVR. Results: Out of 48 patients included (median age 16 years, age range 13 to 23 years, 71% male), impaired CFVR was found in 21 patients (44%). These patients had decreased longitudinal tricuspid annular plane systolic excursion (TAPSE), greater Z scores for left ventricular end-systolic dimensions and higher mean pulmonary artery pressures (mPAP). CFVR showed modest but significant positive correlations with tricuspid annular plane systolic excursion (TAPSE). Left pulmonary artery branch stenosis, reduced TAPSE and mPAP ≥ 20 mmHg, were significantly associated with impaired CFVR, while decreased TAPSE remained independent predictor in multivariable analysis (odds ratio 5.6, 95% confidence interval 1.24-25.26, p = 0.025). Conclusions: Impaired CFVR appears to be frequently observed in adolescents after uncomplicated neonatal ASO for simple D-TGA. Importantly, impaired CFVR is associated with right ventricular dysfunction.