Background: AL-amyloidosis is a rare disease associated with extracellular deposition of the amyloidogenic immunoglobulin light chains (AL). Heart disease is a major determinant of prognosis in patients with AL-amyloidosis.
Objective: To evaluate potential predictors of progression of AL-amyloidosis in patients with heart and renal involvement.
Methods: We followed 55 patients with biopsy-proven AL-amyloidosis (33 male; median age 57 years (51–66)) who underwent electrocardiogram (ECG), standard echocardiography (Echo), pulsed-wave tissue Doppler imaging (TDI). N-terminal pro-brain natriuretic peptide (NT proBNP) was measured in 34 patients. The glomerular filtration rate (GFR) was estimated with the CKD-EPI equation. 29 patients (53%) had clinical manifestations of heart failure (NYHA class I in 7%, class II in 22%, class III in 20%, class IV in 4%). Advanced chronic kidney disease (CKD stage 3–5) with GFR<60ml/min was diagnosed in 22 participants (40%). The median follow-up period was 44 months (range: 8–56 months).
Results: In 24 patients (group 1) there was stable course of disease during follow-up while 31 patients (group 2) showed progression of amyloidosis and died. Patients in group 1 had lower median baseline NT proBNP level (323.7 vs 5822.0ng/L; p=0,003), interventricular septum thickness (1.2 vs 1.5cm; p=0.0005) and left atrium size (3.6 vs. 3.9cm; p=0,03) and higher left ventricular ejection fraction (61 vs 56%; p=0.001). Low QRS voltages on ECG and transmitral diastolic blood flow parameters (E, A, E/A) had no predictive value. TDI parameters associated with unfavorable outcomes included low peak early E' (median: 8 vs 6.0cm/s in groups 1 and 2, respectively; p=0,02) and low peak late A' (10.5 vs 7.25 cm/s; p=0,004) diastolic lateral mitral annular velocities. Patients who showed cardiac amyloidosis progression had high E/E' ratio (6.6 vs 10.4 in groups 1 and 2, respectively; p=0,008) and low systolic S' lateral mitral annular velocity (10.5 vs 7.0cm/s; p=0,004). However, in patients with early chronic kidney disease (CKD stage 1–2) TDI indices (S', E', A') and NT proBNP levels along with standard Echo findings did not affect prognosis.
Conclusions: NT proBNP level, left atrium size, interventricular septum thickness and TDI data (S', E', A', E/E') are strong predictors of unfavorable prognosis in patients with cardiac and renal AL-amyloidosis, provided that GFR is considered in interpreting their clinical signficance. In patients with normal or near-normal renal function (CKD stage 1–2, GFR ≥60 ml/min) the predictive value of standard Echo, TDI and NT proBNP is reduced.