Usefulness of Regional Longitudinal Strain to Identify Transthyretin Amyloid Cardiomyopathy

Abstract

Background

Evaluation of the utility of regional longitudinal strain (LS) to identify transthyretin amyloid cardiomyopathy (ATTR-CM).

Methods and Results

From 2016 to 2019 we enrolled 66 patients aged ≥70 years who underwent ^{99 m}Tc-labeled pyrophosphate scintigraphy and had enough information for 2-dimensional speckle-tracking echocardiography. Patients were divided into ATTR-CM group (n=37) and non-amyloid cardiomyopathy group (n=29). Basal inferior LS was significantly lower in the ATTR-CM group than in the non-amyloid cardiomyopathy group (4.6±3.9 vs. 10.7±5.4, P<0.01). ROC analysis showed that the basal inferior LS value was useful for identifying ATTR-CM (area under curve: 0.86).

Conclusions

Basal inferior LS value is the most useful for identifying ATTR-CM.

Central Figure.

Left ventricular (LV) apical sparing (i.e., the longitudinal strain (LS) in the basal and middle segments of the LV is more severely impaired than that in the apical segment) is highly specific for amyloid cardiomyopathy,¹ but the usefulness of regional LS values to identify transthyretin amyloid cardiomyopathy (ATTR-CM) has not been fully evaluated.

Methods

From 2016 to 2019 we enrolled 66 patients aged ≥70 years who underwent ^{99 m}Tc-labeled pyrophosphate scintigraphy and had enough information for 2-dimensional speckle-tracking echocardiography, which was performed using the same equipment (EPIQ 7G). Measurement of LS was by semi-automatic assessment (TomTec-Arena, TomTec Imaging Systems), and the regional LS values of the ATTR-CM and non-amyloid cardiomyopathy groups were compared using Student’s t-test. Receiver operating characteristic (ROC) analysis was performed to evaluate the usefulness of regional LS to predict ATTR-CM. Statistical analyses were conducted with SPSS version 24.0.

Results

Among the enrolled patients, 37 were ATTR-CM and 29 were non-amyloid cardiomyopathy (14 aortic stenosis [AS], 6 hypertrophic cardiomyopathy [HCM] and 9 unclassified). Figure A,B shows representative LS values in patients with ATTR-CM and non-amyloid cardiomyopathy. Various segmental LS measurements, including the basal inferoseptal and inferior LS, were significantly lower in the ATTR-CM group than in the non-amyloid cardiomyopathy group (Figure C,D). Figure E–G shows the ROC analysis to identify ATTR-CM: the area under the curve (AUC) of the basal inferior LS was highest (0.86) among all regional LS values.

Figure.

Representative regional LS values in patients with ATTR-CM (A) and non-amyloid cardiomyopathy (B). Average LS between ATTR-CM (C) and non-amyloid cardiomyopathy (D) groups. *P<0.05 vs. non-amyloid cardiomyopathy. Receiver operator characteristic curve analysis of basal (E), mid (F) and apical (G) LS values to predict ATTR-CM. A, anterior; AL, anterolateral; AS, anteroseptal; ATTR-CM, transthyretin amyloid cardiomyopathy; AUC, area under the curve; I, inferior; IL, inferolateral; IS, inferoseptal; LS, longitudinal strain.

Discussion

Tsuruda et al. reported that deformation in the basal inferoseptal segment was persistent in asymptomatic ATTR-CM patients,² and in our present study also, the basal inferoseptal LS was lowest in the ATTR-CM group. However, impaired inferoseptal segments were also seen in the non-amyloid cardiomyopathy group, but in that group LV wall stress was considered to be elevated because many patients have AS and HCM. Kocabay et al. showed that the basal septal segment in healthy adult volunteers exhibited lower LS values than the other segments.³ Thus, the basal septal segment may be susceptible to various conditions, including elevated LV wall stress, and may explain why the basal septal LS was attenuated in the non-amyloid cardiomyopathy group.

In our study, the basal inferior LS was impaired in ATTR-CM group, but not in the non-amyloid cardiomyopathy group. Tsuruda et al. also showed that the inferior segment was impaired even in asymptomatic ATTR-CM patients.² Therefore, the inferior segment as well as the inferoseptal segment may be highly susceptible to amyloid infiltration. The regions affected by amyloid deposition may be different from those affected by LV wall stress.

LV apical sparing is useful to differentiate amyloid cardiomyopathy,¹ but takes time and effort to evaluated. Our findings suggest that the basal inferior LS value is enough to differentiate amyloid cardiomyopathy from non-amyloid cardiomyopathy, which might save time and effort when identifying ATTR-CM.

Study Limitations

This was a single-center retrospective cohort study of a small number of patients.

Conclusions

The basal inferior LS is the most useful for predicting ATTR-CM, which may lead to timely identification of ATTR-CM patients.

Disclosure

K.T. is a member of Circulation Reports’ Editorial Team.

Declaration of Competing Interest

None.

IRB Information

This study was approved by the IRB and ethics committee of Kumamoto University (Reference number: 1588).

Funding Statement

Source of Funding: Research grant from GE Health Care Japan.

Data Availability

The deidentified participant data will not be shared.