A new staging system using right atrial strain in patients with immunoglobulin light-chain cardiac amyloidosis.

Abstract

There are minimal data on the prognostic impact of right atrial strain during the reservoir phase (RASr) in patients with immunoglobulin light-chain (AL) cardiac amyloidosis. Among 78 patients who were diagnosed with AL cardiac amyloidosis at Kumamoto University Hospital from 2007 to 2022, 72 patients with sufficient two-dimensional speckle tracking imaging data without chemotherapy before the diagnosis were retrospectively analysed. During a median follow-up of 403days, 31 deaths occurred. Age and the rate of male sex were not significantly different between the all-cause death group and the survival group (age, 70.4±8.8years vs. 67.0±10.0years, P=0.14, male sex, 65% vs. 66%, P=0.91). The estimated glomerular filtration rate (eGFR) was significantly lower, and B-type natriuretic peptide (BNP) and high sensitivity cardiac troponin T (hs-cTnT) were significantly higher, in the all-cause death group versus the survival group (eGFR, 48.2±21.0mL/min/1.73m2 vs. 59.4±24.4mL/min/1.73m2 , P<0.05, BNP, 725 [360-1312] pg/mL vs. 123 [81-310] pg/mL, P<0.01, hs-cTnT, 0.12 [0.07-0.18] ng/mL vs. 0.05 [0.03-0.08] ng/mL, P<0.01). Left ventricular (LV) global longitudinal strain (GLS) (LV-GLS), left atrial strain during the reservoir phase (LASr), right ventricular GLS (RV-GLS), and RASr were significantly lower in the all-cause death group versus the survival group (LV-GLS, 8.5±4.3% vs. 11.8±3.8%, P<0.01, LASr, 8.8±7.1% vs. 14.3±8.1%, P<0.01, RV-GLS, 11.6±5.1% vs. 16.4±3.9%, P<0.01, RASr, 10.2±7.3% vs. 20.7±9.5%, P<0.01). RASr was significantly associated with all-cause death after adjusting for RV-GLS, LV-GLS and LASr (hazard ratio [HR]: 0.91, 95% confidence interval [95% CI]: 0.83-0.99, P<0.05). RASr and log-transformed BNP were significantly associated with all-cause death after adjusting for log-transformed troponin T and eGFR (RASr, HR: 0.93, 95% CI: 0.87-1.00, P<0.05; log-transformed BNP, HR: 2.10, 95% CI: 1.17-3.79, P<0.05). The optimal cut-off values were RASr: 16.4% (sensitivity: 66%, specificity: 84%, area under curve [AUC]: 0.81) and BNP: 311.2pg/mL (sensitivity: 83%, specificity: 78%, AUC: 0.82) to predict all-cause mortality using ROC analysis. Kaplan-Meier analysis revealed that patients with low RASr (<16.4%) or high BNP (>311.2pg/mL) had a significantly high probability of all-cause death (both, P<0.01). We devised a new staging score by adding 1 point if RASr decreased or BNP levels increased more than each cut-off value. The HR for all-cause death using score 0 as a reference was 5.95 (95% CI: 1.19-29.79; P<0.05) for score 1 and 23.29 (95% CI: 5.37-100.98; P<0.01) for score 2. The new staging system using RASr and BNP predicted prognosis in patients with AL cardiac amyloidosis.