The mean LAVi in our study population is higher than in the healthy population as well as in CKD population. The mean LAVI in our dialysis patients was 38.93+/- 10.57 ML/M2 as compared to 21.96 +/- 4.189ML/M2 in the normal population and as compared to 33.33 +/- 11.71 ML/M2in the CKD population. [18–19]
In previous studies, LAVi has been shown to be significantly higher in dialysis patients than in healthy subjects. In a study done by Seung Jun Kim et al increased left atrium volume index (LAVI > 32 mL/m 2 ) was observed in 99 (45.8%) of the CAPD patients [31].
Our study showed that LAVi is an independent predictor of mortality in Hemodialysis patients and as LAVi increases mortality increases. Among all echocardiographic parameters, LAVi is the strongest predictor of Mortality in our ESRD patients. Similar findings were seen in a study by Mayo Clinic of a large cohort of more than 10,000 patients which showed that with every milliliter per square meter increase in LAVi, all-cause mortality risk increased by 3% (hazard ratio [HR], 1.03; 95% CI, 1.02–1.04; P < .001) [32]. Abhayaratna et al in their study showed that LAVi of 34 mL/m2 or greater was an independent predictor of death, heart failure, atrial fibrillation, and ischemic stroke.
Currently most of the focus is on LA volume, which is also a component of the algorithm for Diastolic dysfunction of LV,, in addition to LVH and LV systolic and diastolic dysfunction as an indicator of CV outcomes. It is reported that LA size is a more stable indicator to reflect the severity and chronicity of diastolic dysfunction than any other echocardiographic parameter although it is largely determined by the same factors that influence diastolic LV filling. [33] The E/e’ ratio accurately reflects the filling pressures at the time of the examination. In contrast, the LAV is a reflection of the long-term exposure to LV filling pressures. It reflects the beat-to-beat interaction of LV filling pressure and ventricular compliance, making them sensitive to rapid alterations in ventricular preload and afterload
In line with these findings, we demonstrated that increased LAVI was an independent risk factor for mortality, suggesting that LAVI is a more reliable predictor of mortality in patients on hemodialysis as compared to E/e’ and EF which are dependent on multiple factors including loading conditions and volume status.
Using the ROC curve and Pearson chi square test we found out that the best cut off value for LAVi that gives significant association with mortality is greater than 38.5 ml/m2 in our dialysis population. LAVi had a significant positive association with mortality. The American Society of Echocardiography criterion for moderate LA dilatation is LAVI > 40 ml/m2, at which the odds ratio was 3.5 in our study.
Only a few studies have evaluated the relationship of LAVi with mortality in ESRD patients. LAVi has shown to be an independent predictor of CV morbidity and mortality in the general population and, more specifically, in ESRD patients on chronic dialysis [30,, 34, 35, 36]The study conducted by Seung Jun Kim et al in 216 patients with CAPD showed that increased LAVI was an independent predictor of all-cause mortality [hazard ratio (HR) 1.05, P = 0.03] and cardiovascular mortality (HR 1.08, P = 0.006). [30]
The E/e’ ratio accurately reflects the filling pressures at the time of the examination. It reflects the beat-to-beat interaction of LV filling pressure and ventricular compliance, making them sensitive to rapid alterations in ventricular preload and afterload. In contrast, the LAV is a reflection of the long-term exposure to LV filling pressures. In a Mayo Clinic Study, Left atrial enlargement was independently associated with an increased risk of all-cause mortality in a large cohort of 10,719 patients with normal Left ventricular filling pressure and preserved LVEF. [37]
In the present study, we can surmise that patients with enlarged LA were volume expanded, which might explain the higher mortality rate in these patients. Therefore, more attention should be paid to better control of fluid overload in patients with enlarged LA.
Limitations
This study has been done in our population in Pakistan and the relationship of LAVi with mortality may not be generalised to the general population.
Echocardiographic examinations were performed only at one point in time, it was difficult to determine the consequence of the changes of echocardiographic parameters on patients’ clinical outcome. Serial follow-up echocardiography examinations may be of help in understanding the natural history of LA remodeling in HD patients [38]
Number of patients was not large. A larger sample size would further help to improve the significance of the statistical analysis.