Chronic Kidney Disease is Independently Associated with Alterations in Left Atrial Function

Background: Chronic kidney disease (CKD) is associated with increased cardiovascular morbidity and mortality; hence detection of early cardiovascular involvement in CKD is important to prevent future adverse cardiovascular events. Left atrial (LA) enlargement and dysfunction has been reported in end stage renal disease. However, there is a paucity of published data regarding the evaluation of LA function in CKD using noninvasive imaging parameters. In this study, we evaluated biplane LA volume as well as LA function (LA global systolic strain (GS) and strain rate [SR]) in stage 3 CKD patients (eGFR 30-59 mL/min per 1.73 m(2)) to determine if LA function parameters are more significantly altered by the presence of CKD in addition to changes due to hypertension alone. Methods: Thirty-three CKD patients (eGFR 30-59 mL/min per 1.73 m(2)) with hypertension were compared to 33 normal controls and 34 hypertensive (HT) subjects with normal renal function; all participants underwent a detailed transthoracic echocardiogram. Indexed biplane LA volume (LAVI), LA segmental function, and GS and SR (systolic, early, and late diastole) derived from tissue Doppler imaging (TDI) were measured. Univariate predictors of LA strain were determined. Multiple logistic regression analysis was used to examine the effect of patient group (i.e. CKD) on GS and SR as well as LAVI. Results: Left atrial volume indexed was significantly increased in both the HT and CKD with HT group compared to normal controls (28 +/- 9 mL/m(2) vs. 28 9 mL/m(2) vs. 23 +/- 5 mL/m(2), respectively, P = 0.02). However, LAVI was similar in the HT and CKD with HT group (28 +/- 9 mL/m(2) vs. 28 +/- 9 mL/m(2); P = NS). LA GS and SR were reduced in both the CKD with HT and HT group, compared to controls. However, a significantly lower LA GS was present in the CKD with HT group (Controls vs. HT vs. CKD with HT: 54.9 +/- 14.5% vs. 34.5 +/- 6.2% vs. 25.7 +/- 9.3%, respectively; P = 0.001). To examine the effect of group, (i.e. presence of CKD) multiple logistic regression analysis was performed with univariate predictors including indexed left ventricular mass (LVMI), LV diastolic grade, LAVI, peak A-wave velocity, beta-blocker therapy, GS and SR; this demonstrated that CKD had an independent effect on LA GS and SR (systolic, early, and late diastole). GS demonstrated moderate correlation with systolic blood pressure (r = -0.5, P = 0.01), diastolic grade (r =+/- 0.5, P = 0.01), E' velocity (r = 0.6, P = 0.0001), peak A velocity (r = -0.5, P = 0.004), and LAVI (r = +/- 0.6, P = 0.002). Conclusions: Left atrial dysfunction is evident in stage 3 CKD with associated LA enlargement. This study demonstrates that LA GS and SR were reduced in the CKD group despite similar LAVI in the CKD with HT and HT group. Hence LA GS and SR may be a more sensitive noninvasive tool to detect cardiovascular involvement in CKD.