I read with interest the article “Exercise Echocardiography Demonstrates Biventricular Systolic Dysfunction and Reveals Decreased Left Ventricular Contractile Reserve in Children after Tetralogy of Fallot Repair” by Roche et al . In my opinion, this is an excellent report describing that exercise echocardiography provides additional information on biventricular abnormalities in postsurgical children with tetralogy of Fallot (TOF), which also reveals abnormal left ventricular (LV) excitation-contractile coupling. I want to highlight that Roche et al . for the first time showed early abnormalities of biventricular systolic function and markedly reduced LV contractile reserve in asymptomatic children with TOF repair. In addition, I agree with the authors’ statement that there is a lack of data addressing the relation between right ventricular (RV) long-axis function, RV-LV interaction, and the presence of clinical symptoms in children with repaired TOF. The authors stated that Doppler tissue imaging parameters, such as tricuspid annular peak systolic velocity (S′) and mitral annular peak systolic velocity (Sm), provided useful information about systolic RV function in their children with TOF during resting and exercise echocardiography. They described a modified measurement of tricuspid annular plane systolic excursion and mitral tricuspid annular plane systolic excursion, expressed as percentage changes in length from diastole to systole (long-axis fractional shortening [FS]), which they found useful for the detection of an impaired myocardial response in both ventricles in children with repaired TOF. I invite the authors to provide more information about this specific calculation for the audience of JASE , in particular about normal ranges of the percentage changes in healthy children. In imaging guidelines for patients with TOF, impairment of RV Doppler tissue imaging parameters and M-mode parameters in comparison with available normative values is described as useful for the detection of RV systolic dysfunction. It would therefore also be of interest for to readers how Doppler tissue imaging parameters in patients with repaired TOF in their study compare with available age-dependent parameters. A comparison of their S′ and Sm data with available normal S′ and Sm Z scores, in my opinion, will improve the statistical power of their analysis. Roche et al . also demonstrated marked RV outflow tract (RVOT) systolic dysfunction in children with repaired TOF using an innovative parameter, RVOT FS. Their findings significantly add to the developing knowledge about the key role of RVOT function in global normal RV function. May I ask if the authors agree with my suggestion that in addition to the measured RVOT FS, a determination of RVOT systolic excursion, when compared with available normative values, will have a beneficial effect in determining impaired RVOT systolic function in patients with repaired TOF?

I want to thank the authors for addressing the need for a careful and systematic evaluation of RV functional parameters and cardiac biomarkers in patients with TOF early after surgical repair, and I strongly support their notion that exercise echocardiography provides important additional information about systolic biventricular function and ventricular-ventricular interaction.