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 veloc-ity reserve (CFVR) and aimed to identify echocardiographic and clinical predictors of coronary microvascular dysfunction in adolescents after neonatal arterial switch op-eration (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 ventricu-lar strain measurement (GLS) and cardiac catheterization, including coronary angi-ography. Coronary flow velocity reserve was assessed by transthoracic Doppler echo-cardiography 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 relationship between CFVR and echocardiographic variables. Binary lo-gistic 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 de-creased longitudinal tricuspid annular plane systolic excursion (TAPSE), greater Z-scores for left ventricular end-systolic dimensions and higher mean pulmonary ar-tery pressures (mPAP). CFVR showed modest but significant positive correlations with tricuspid annular plane systolic excursion (TAPSE). Left pulmonary artery branch ste-nosis, reduced TAPSE and mPAP≥ 20 mmHg, were significantly associated with im-paired CFVR, while decreased TAPSE remained independent predictor in multivaria-ble analysis (odds ratio 5.6, 95% confidence interval 1.24-25.26, p=0.025). Conclusions: Impaired CFVR is highly prevalent in adolescents after neonatal ASO. Importantly, impaired CFVR is associated with right ventricular dysfunction.