Usefulness of STREI: A new index of right heart function in patients with immunoglobulin light chain cardiac amyloidosis.

AIMS: To evaluate the prognostic effect of a novel index by two-dimensional speckle-tracking echocardiography (STREI index) integrating right atrial (RA) and right ventricular (RV) strain in patients with immunoglobulin light chain (AL) cardiac amyloidosis.

METHODS

Ninety patients were diagnosed with AL amyloidosis at Kumamoto University Hospital from 2007 to 2022. Among these patients, 70 with evidence of cardiac amyloidosis and sufficient echocardiographic data at diagnosis, including RA and RV strain analysis, were retrospectively analysed. The STREI index was developed with the following formula: [2 × RV - free wall longitudinal strain (RV - FWLS) + RA strain during the reservoir phase].

RESULTS

During a median follow-up of 854 days (interquartile range, 151-1787 days), 33 deaths occurred. The STREI index was significantly lower in the all-cause death group than in the survival group (40.5 ± 19.9 vs. 57.7 ± 18.9, p < 0.01). The STREI index was significantly and independently associated with all-cause death after adjusting for left ventricular global longitudinal strain and left atrial strain during the reservoir phase (hazard ratio: 0.96, 95 % confidence interval: 0.93-0.98, p < 0.01). The optimal cut-off value was an STREI index of 50 % (sensitivity: 78 %, specificity: 72 %, area under curve: 0.80) to predict all-cause mortality using receiver operating characteristic analysis. A Kaplan-Meier analysis showed a significantly higher risk of all-cause death and cardiovascular death in patients with a low STREI index (<50 %, n = 32) than in those with a high STREI index (≥50 %, n = 38) (both p < 0.01).

CONCLUSIONS

The STREI index, which is a new index of total right heart function, might be useful for predicting the prognosis in patients with AL cardiac amyloidosis.