Baseline serum sodium as a non-negligible factor predicting increased risk of 3-month mortality in patients with light-chain amyloidosis diagnosed in cardiology department

Introduction and purpose The light-chain amyloidosis (AL) with cardiac involvement is commonly diagnosed in cardiology department. Early mortality of these patients remains an unsolved issue despite of up-to-date and effective treatment. The aim of this study was to identify predictors of 3-month mortality among parameters routinely tested in cardiology department. Methods This was a retrospective analysis of consecutive patients with AL cardiac amyloidosis diagnosed in the cardiology department from August 2011 to August 2024. The study population was divided into two subgroups based on 3-month survival. The analysed data comprised: severe weight loss (SWL) defined as >10 kg within one year, systolic (SBP) and diastolic blood pressure (DBP) on admission, baseline electrolytes, creatinine, N-terminal pro-B-type natriuretic peptide (NT-proBNP) and high-sensitivity troponin T (hs-TnT) concentrations. Echocardiographic parameters collected were: thickness of interventricular septum (IVS) and left ventricular posterior wall (PW), left (LAA) and right atrial area (RAA), left ventricular ejection fraction (LVEF), and stroke volume (SV), tricuspid annular plane systolic excursion (TAPSE), longitudinal myocardial velocity of right ventricle (RV s’) and average longitudinal myocardial velocity of left ventricle (LV s’) estimated by tissue Doppler imaging, diameter and collapsibility of inferior vena cava (IVC), presence and amount in mm of pericardial effusion (PE). Results The study group consisted of 141 patients (77 males) with a median age of 65 years (IQR 56-70). The all-cause mortality within three months was 17.7%. Significant (p<.05) predictors of 3-month mortality identified in the univariate Cox proportional hazard model were: DBP, SBP, sodium, NT-proBNP, hs-TnT, LVEF, LV s’, RV s’, SV, TAPSE, IVC diameter, PE in mm, SWL, IVC dilation and decreased collapsibility. Two multivariate Cox proportional hazard models (p<.0001) were created using non-collinear significant predictors: the first model (Chi2 25,83; Herrell’s C-index 0.795) included DBP and LVEF with hazard ratios (95% confidence intervals) of 0.96 (0.93-1.00) and 0.93 (0.90-0.96), respectively and the second model (Chi2 23,54; Herrell’s C-index 0.792) included SBP and sodium concentration with hazard ratios of 0.96 (0.94-0.99) and 0.87 (0.80-0.95), respectively. The Kaplan-Meier curve confirmed that SBP ≤120 mmHg, DBP ≤81 mmHg, sodium ≤136 mmol/l, and LVEF ≤45%, were associated with worse survival (Log-rank test, p<.05). ROC curves comparison revealed no differences between sodium (AUC=0.650; 95% CI=0.561-0.731), hs-TnT (0.798; 0.716-0.865) and NT-proBNP (0.791; 0.709-0.858) in 3-month mortality prediction (p>.05). Conclusion Baseline serum sodium concentration in addition to diastolic and systolic blood pressure on admission and left ventricular ejection fraction are among prognostic factors of 3-month mortality in patients diagnosed with AL cardiac amyloidosis.