Conventional echocardiographic measurements of ejection fraction and fractional shortening have limitations in evaluating myocardial function and detecting early stages of decreasing LV systolic function. They are highly operator-dependent and heavily dependent on image quality, geometrical variables, and image orientation. Speckle-tracking echocardiography provides a promising emerging tool for early detection of LV systolic dysfunction that is not hindered by these limitations [6, 8].

This study measured longitudinal and circumferential LV strain using 2DSTE in children after cardiac surgery. Study subjects were divided according to age at follow-up into four groups (1 month–1 year, 1–2 years, 2–5 years, and 5–11 years). The data were compared to published reference normal values for each age group. [16] Longitudinal strain values were significantly lower than reference values for different age groups. Global circumferential strain values showed either nonsignificant differences or statistically significant higher values compared to the reference values.

In twenty-two children at least nine years of age after arterial switch operation for D-TGA. The global LV longitudinal strain of − 18.3 ± 1.3%, was significantly lower than healthy controls, and a global circumferential of − 26 ± 2.5%, was not different from the healthy control group. There was no significant correlation between strain values and operative variables (cardiopulmonary bypass time and cross-clamp time). The decrease in longitudinal strain in this patient group could indicate subclinical myocardial dysfunction [17].

At more than one year after correction of TOF, patients aged 8–18 years [18], 5–25 years [19], 1.5–16 years [20], and 18.7 ± 6 years [21] showed a decrease in LV strain compared to healthy controls, and it decreased with increasing age. The LV longitudinal strain was reported to be in the range of − 19.07 ± 2.1819 shortly (on the 8th day) after TOF repair, which was significantly lower than normal controls [12].

Perdreau et al. studied thirty-three patients with a mean age of 4.2 years before and immediately after different cardiac surgeries: ASD, VSD, AVSD, TOF, TGA, LVOTO, and valvular insufficiency. They found significant differences in longitudinal and radial strain but no difference in circumferential strain between preoperative and postoperative measurements [22]. Similar results were reported in 25 children with a mean age of 9.4 years studied preoperatively, one week, and one month postoperatively [10].

The findings in the current study agree with the abovementioned studies, with either near-term or long-term postoperative results showing global longitudinal strain significantly lower than normal values either measured preoperatively or compared to normal controls. Our findings are consistent with previous studies that have reported no significant differences in circumferential strain [17, 22]. The decrease in longitudinal strain values may be due to the selective hypoperfusion of longitudinal fibers, resulting in severe ischemia [23].

The present study presents a significant improvement in longitudinal strain in patients following cardiac surgery within the first year. However, the study findings indicate that the longitudinal strain values remain significantly lower than normal while having normal left ventricle ejection fraction by conventional echocardiography. This outcome emphasizes the importance of continued monitoring and managing patients after cardiac surgery to optimize their recovery and long-term outcomes. According to data reported by Van der Ende et al., the strain values recovered after surgical intervention of aortic stenosis or aortic coarctation. However, the values never reached normal even after a mean follow-up period of 42 weeks [24]. In addition, a study by Grotenhuis et al. showed decreased global systolic function detected by magnetic resonance imaging 16 years after an arterial switch operation [25]. This suggests that the current study’s findings may represent primary myocardial dysfunction that may later become more apparent by standard measurements of left ventricular function.

The present study is limited to a single center and a relatively small sample size for each cardiac anomaly. Hence, the findings obtained cannot be extrapolated to the broader population. This caveat necessitates caution in interpreting the results and precludes generalization of the findings. Moreover, our study could not provide long-term follow-up of longitudinal strain data to assess the course of a specific disease. The study’s design did not allow for accurate evaluation of disease progression due to the inclusion of patients at various age groups and postoperative intervals. The different follow-up intervals and the limited number of subjects might also affect the correlation between the strain values and operative and postoperative parameters. These limitations underscore the need for future research to employ a more focused cohort selection strategy. Finally, it should be noted that the current study did not compare the postoperative data with preoperative data. Instead, relied on the use of published normal values. Nevertheless, the findings demonstrate a similarity to those of earlier studies that have examined comparable healthy controls.