This is the first study to demonstrate that LASr_c is a prognostic predictor of all-cause mortality or MACEs in stable dialysis patients with preserved LVEF. We showed that LASr_c was the independent predictor of all-cause mortality or MACEs and those patients with less LASr_c ( LASr_c<32.9%) had a higher mortality or MACEs rate. Thus, we highlighted the clinical application of LASr_c for risk assessment in clinically stable dialysis patients with preserved LVEF. It is also recommended that left atrial function was assessed using left atrial longitudinal strain together with circumferential strain.
Due to technical constraints, only LA longitudinal strain could previously be measured, and therefore the prior studies were focused on LA longitudinal strain[10, 11]. In this study, dedicated 4DSTE was used to quantify left atrial longitudinal strain in addition to circumferential strain. In line with previous studies, we discovered that LASr and LASct were significantly lower in the event group[12]. LASr_c and LASct_c similarly exhibited a significant decline.
The prognostic value of LA longitudinal strain in ESRD patients is well established and clearly associated with functional abnormalities[3, 12], which is consistent with our results. However, the LASr_c has not been proved as an outcome predictor in ESRD patients having preserved LVEF. This study showed that less LASr_c ( LASr_c<32.9%) and LASct_c(LASct_c<19.6%) had higher all-cause mortality or MACEs rate in stable dialysis patients with preserved LVEF.
Less LA longitudinal strain may be linked to myocardial fibrosis, myocardial stunning concerning dialysis, or microvascular ischemia caused by a decrease in myocardial capillary density[13, 14]. Therefore, Less LA longitudinal strain is a reliable and early parameter to identify LA myocardial fibrosis or ischemia before overt LA dysfunction. LA longitudinal strain is also proved as a powerful predictor of all-cause mortality or MACEs[15]. The mechanism for the reduction in left atrial longitudinal strain may be applied to the left atrial circumferential strain. This might indicate that abnormal LA geometry and function are responsive to less longitudinal and circumferential strain. Our study found that left atrial circumferential strain, like left atrial longitudinal strain, appeared to be decreased in the event group and similarly independently predicted all-cause mortality or MACEs in ESRD patients with preserved LVEF. The association between LAS and LASr_c might reflect that they may share common mechanisms (e.g., myocardial injury, interstitial fibrosis, myocyte hypertrophy) and result in poor outcomes.
According to previous studies [16–18], left atrial longitudinal strain is a more accurate and sensitive metric for describing LA function in people with cardiomyopathies, advanced-stage chronic kidney disease, or atrial fibrillation. Less LA longitudinal strain was also proved to be an effective predictor of all-cause mortality in the general population and had been associated with a variety of different cardiomyopathies, including diabetes, hypertrophic cardiomyopathy, and amyloidosis[19–21]. The present study showed that 4D STE enables the comprehensive assessment of LA function with excellent reproducibility. Thus, this imaging modality might contribute to better clinical assessment of ESRD patients with preserved LVEF.
Due to the small sample size and a significant association, we did not include these two factors (LAS and LASr_c) in one Cox model so we could not identify which one is more powerful in predicting all-cause mortality or MACEs. Nevertheless, it is worth mentioning that dedicated left atrial 4DSTE provides more information to assess LA functions in ESRD patients.
This study has some limitations. First, due to the short follow-up duration and low death rate, mortality or MACEs could not be predicted independently. Second, LA strain analysis was not available for some dialysis patients due to severe valvular heart disease, atrial fibrillation, or poor echocardiographic image quality. Finally, the predictive sensitivity of the longitudinal and circumferential strains could not be provided in this research, considering the fact that the significant association between LA longitudinal and circumferential strain.