To the best of our knowledge, there are only a limited number of studies focusing on echocardiographic changes associated with CAP in children. In our research, we assessed cardiac function in children diagnosed with CAP using various echocardiographic modalities, including conventional echocardiography, TDI, and 2D-STE.

LV-related findings suggested significant deterioration in LV systolic function, as evidenced by a decrease in S’ observed by TDI and a decrease in global longitudinal strain (GLS) assessed by 2D-STE. In contrast, no significant differences were found in FS% measured in M ​​mode or LV diastolic function assessed by E’/A’ ratio in children with CAP.

The differences observed in our systolic function results assessed in M-mode as opposed to TDI and 2D-STE may be attributed to the limited sensitivity and specificity of parameters derived from M-mode as well as the advantages of alternative echocardiographic techniques. LV (GLS) facilitates early detection of myocardial dysfunction before significant changes in fractional shortening (FS) or ejection fraction (EF) occur [22].

Our results are consistent with those of Metawee et al., who reported significantly lower S’ in children diagnosed with pneumonia, suggesting the presence of LV systolic dysfunction in these patients [23]. Similar to our results, they observed no significant difference in diastolic function between cases and controls when assessed by TDI. However, their analysis using conventional pulsed Doppler revealed a notable decrease in both the E wave and the E/A ratio in pneumonia cases compared to the control group.

Orabi et al. conducted an assessment of cardiovascular dysfunction in pediatric patients diagnosed with pneumonia [24]. Their study used conventional echocardiography, TDI, and 2D-STE techniques. The results suggested the presence of LV systolic and diastolic dysfunction and LV hypertrophy. Consistent with our results, they observed a reduction in LV GLS. In addition, they found significant impairments in several echocardiographic parameters in their patients, including LV E/E`, LV end-diastolic volume (EDV), aortic strain, and LV interventricular septal thickness during diastole (IVSd).

In contrast to our research, Atta et al. identified notable diastolic dysfunction within the affected group, as evidenced by the septal and lateral E/e’ ratio [25]. However, there was no significant difference in systolic function. Furthermore, Kalra et al. showed that diastolic dysfunction associated with pneumonia occurs before systolic impairment [26].

Conversely, alternative studies suggested that pediatric patients with pneumonia or lower respiratory tract infections had normal LV dimensions and functions in their findings [27,28,29].

Regarding RV functions, in our research, we noticed a significant RV diastolic dysfunction measured by E’/A’ and MPI, while there was no significant difference in RV systolic function (S’) measured by TDI, compared to the control group. This finding is in contrast to that of Metawee et al. conducted a study that reported a significant decline in RV systolic function assessed using conventional echocardiography by measuring tricuspid annular plane systolic excursion (TAPSE) [23].

Various studies have demonstrated an increase in RV systolic pressure in children diagnosed with pneumonia [28, 29]. Furthermore, Shehan et al. reported that RV heart failure secondary to pulmonary hypertension occurred in 26% of 47 children with pneumonia [30].

According to our results, the MPI for both ventricles was significantly increased in the diseased group compared to the control group. The MPI serves as a measure of systolic and diastolic function and acts as a sensitive marker for symptomatic heart failure. It reflects the severity of ventricular dysfunction and has been established as an independent prognostic factor for mortality [31]. This aligns with the findings of Nimdet K et al., who observed in their research on pediatric pneumonia that there was a notable deterioration in MPI of both the right and left ventricles at the time of admission, indicating improvement showed during the follow-up period [32]. Additionally, Kaya et al. found that the MPI was significantly higher in patients with COVID-19 pneumonia than in controls [33].

In our research, an analysis comparing the subgroups of complicated and non-complicated CAP revealed that there were no statistically significant differences in echocardiographic parameters. This finding is consistent with the conclusions of Metawee et al., who examined echocardiographic parameters in discharged patients compared with deceased patients. They found that pulsed and TDI along with relevant echocardiographic parameters do not serve as predictors of pneumonia outcome [23].

In contrast, Atta et al. discovered a strong association between hypoxia and the severity of diastolic dysfunction [25]. In addition, echocardiographic parameters can serve as predictive indicators of the outcome of pneumonia, as evidenced by a significant decrease in diastolic function in more complicated cases. Similarly, Orabi et al. identified an association between worsening echocardiographic parameters and the severity of pneumonia [24].

The presence of local pulmonary complications is one of the causes of the failure of childhood CAP treatment. So, in our study, we added anti-staphylococcus antibiotics to fasten the duration of recovery which is in agreement with the previous literature which confirmed that combination antibiotic therapy appeared to be associated with lower mortality among severe cases of CAP [34,35,36,37].

In children aged 5 years and older, in addition to Streptococcus pneumoniae, another significant bacterial cause of pneumonia is Mycoplasma pneumoniae. Therefore, in this study, we included macrolides in the treatment for both groups of children with CAP. None of the patients in either group experienced any complications during their treatment with macrolides. This aligns with previous research recommending the addition of macrolides to the treatment of CAP due to their anti-inflammatory and immunomodulatory activities, in addition to their antibiotic effects [38, 39].

This study has several limitations. First, it is a single-center case-control study with a relatively small sample size. Second, we did not repeat echocardiography to assess cardiac function or to determine the duration required for improvement. Finally, we did not evaluate other cardiac biomarkers, nor did we assess additional hemodynamic parameters like electrolyte levels.

We recommend incorporating cardiac biomarkers in future research to identify early myocardial damage before functional deterioration. These biomarkers may include N-terminal pro-brain (B-type) natriuretic peptide (NT-proBNP), cardiac troponins (cTns), cTnI and cTnT, Midregional-Proadrenomedullin, Adrenomedullin (ADM), and Endothelin-1 (ET-1).