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

Abstract

Aims: 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.

Methods and results: 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 403 days, 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 ± 8.8 years vs. 67.0 ± 10.0 years, 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 ± 21.0 mL/min/1.73 m² vs. 59.4 ± 24.4 mL/min/1.73 m², 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: 311.2 pg/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 (>311.2 pg/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.

Conclusions: The new staging system using RASr and BNP predicted prognosis in patients with AL cardiac amyloidosis.

Keywords: B‐type natriuretic peptide; Immunoglobulin light‐chain cardiac amyloidosis; Right atrial strain during the reservoir phase.

Figure 1

Study flow chart detailing the inclusion and exclusion criteria for the study patients. AL cardiac amyloidosis, immunoglobulin light‐chain cardiac amyloidosis; TTE, transthoracic echocardiography.

Figure 2

Representative example of RA measurement in patients with AL cardiac amyloidosis. White arrow shows RA strain during reservoir phase. RA, right atrial; AL cardiac amyloidosis, immunoglobulin light‐chain cardiac amyloidosis.

Figure 3

Receiver operator characteristic curve analysis of RASr (A) and BNP (B) for predicting all‐cause death. RASr, right atrial strain during the reservoir phase; BNP, B‐type natriuretic peptide; AUC, area under the curve.

Figure 4

Kaplan–Meier curves for all‐cause death in patients with AL cardiac amyloidosis with high or low RASr (A) and low or high BNP (B) based on a previously reported staging system: stage I, II, IIIa and IIIb (C), and the new staging system: score 0, 1, and 2 (D). AL cardiac amyloidosis, immunoglobulin light‐chain cardiac amyloidosis; RASr, right atrial strain during the reservoir phase.