Speckle Tracking Echocardiography for the Diagnosis and Prognosis of Light Chain Cardiac Amyloidosis

Background

Cardiac amyloidosis was thought to be a rare disease, but the data shows that its prevalence rate is increasing, and the light chain (AL) cardiac amyloidosis are the most common and worst ^[1]. Because of the lack of symptoms specificity in the preliminary stages of AL cardiac amyloidosis, resulting in underdiagnosis or severe delays in diagnosis, patients are often delayed in the optimal timing of treatment. A considerable proportion of patients are diagnosed after the onset of symptoms of heart failure which progresses rapidly and results in poor prognosis and high mortality. Patients have a mortality rate of up to 50% within 4-6 months after diagnosis of congestive heart failure and the median survival of these patients were less than 12 months ^[2]. Therefore, early diagnosis and treatment are particularly important for them. Speckle tracking echocardiography has a good imaging analysis of cardiac amyloidosis, which remains the most often used imaging tool. This study aimed to explore the use of speckle tracking echocardiographic parameters to build models which improve the diagnostic rate of patients with suspected AL cardiac amyloidosis and assess the prognosis of patients with AL cardiac amyloidosis.

Methods

We studied twenty-four patients of pathologically confirmed amyloidosis from March 2017 to February 2023 at the First Affiliated Hospital of Soochow University. According to the criteria for organ involvement, patients were divided into two groups based on whether the heart was involved or not and SPSS 26.0 was used to analyze data. The differences of characteristics and various parameters of Speckle tracking echocardiography between two groups were compared and the indicators with statistical difference were selected for single factor analysis and multivariate analysis. Statistically significant factors were used to establish diagnosis and prognosis assessment models as below.

Result

In this study, the rate of cardiac involvement was 62.5%. Until June 30 ^th, 2023, median follow-up time of twenty-four patients was 31 months, and the 5-year survival rate was 74% in CA group and 85.7% in non-CA group.

• Characteristics

The results showed that CA group has lower baseline blood pressure, and the levels of NT-pro BNP and dFLC were significantly higher in the CA group compared to the non-CA group. In speckle tracking echocardiography parameters, CA group has significantly increased IVSd, LVPWd, RWT, E/e and decreased EF, interventricular septum e', lateral wall e' and left ventricular global strain.

• Diagnosis

The results showed that CA group is more likely to be involved in the heart when monoclonal proteins are formed in the peripheral blood （OR=0.031, 95%CI 0.003-0.365, P=0.002）. In univariate analysis, E/e>10.85, interventricular septum e‘<5.25 cm/s, lateral wall e‘<6.05 cm/s, |left ventricular global strain|<16.3% and left ventricular diastolic function ≥Class II have the effect on CA group with statistically significant. Incorporating them into variables to construct a multivariate logistic regression model showed that: the model was built successfully (Omnibus test: P<0.001) and the goodness of fit model is well (Hosmer-Leme show test: P=1). 88.9% of the study subjects who were CA patients were predicted by the model to be CA patients, while 92.9% of the study subjects who were not CA patients were predicted by the model to be not CA patients, but the 5 factors had no significant effect on cardiac amyloidosis (P > 0.05).

• Prognosis assessment

The result of the study shows that IVPWd>13.5mm, RWT> 0.51, NT pro-BNP>6614pg/mL and dFLC>142.35mg/L are elevated risk factors for prognosis with statistically significant. (Figure1). They were included in the variables to construct a multi-factor Cox proportional hazards model and it turns out: the model was built successfully (Omnibus test: P<0.05), but these 4 factors had no significant effect on cardiac amyloidosis (P > 0.05).

Conclusion

Speckle tracking echocardiography is of great value in the diagnosis and prognosis of patients with cardiac amyloidosis. The combined analysis of echocardiography parameters and serological abnormalities can help in the diagnosis and prognostic assessment of the disease, it also helps to identify patients with poor prognosis early and increasing the possibility of future treatment strategies based on risk stratification.