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Page 10 of 29 Aguiar. Rare Dis Orphan Drugs J 2024;3:13 https://dx.doi.org/10.20517/rdodj.2023.56

Strain and strain rate speckle-tracking
New tools like strain and SR speckle-tracking based echocardiography (a TDI-derived technique) enable
measurement of myocardial systolic and diastolic strains, which seem superior and more sensitive than
myocardial velocities (measured by TDI) in quantifying changes of myocardial systolic function, because
they are less influenced by overall cardiac motion .
[105]
Decreased systolic strain and SR of the LV have been reported in FD patients, compared with healthy
controls [106-109] . These alterations in myocardial systolic strains are detectable even in the early stages of FD
cardiomyopathy: there is a significant reduction in both global systolic longitudinal and circumferential
strains, as well as an absence of the normal regional base-to-apex circumferential strain gradient, even in the
subgroup of patients without LV hypertrophy [107,108,110-112] . Global longitudinal strain, mainly basal
longitudinal strain, also correlated with LV mass, T1 mapping, or even the risk of “de novo” atrial
fibrillation, major cardiovascular events, or stroke [110,111,113] . RV strain is also impaired in FD patients, but
[115]
only in the hypertrophic stage and may be lower than in patients with HCM .
[114]
Decreased LV diastolic strain and SR were also reported in FD [106,109] , even in the early phases of FD
cardiomyopathy (patients without LV hypertrophy) and with a higher sensitivity for detecting diastolic
dysfunction compared to using TDI for early diastolic velocities . Left atrial (LA) systolic and diastolic
[109]
strain and SR are also decreased in FD patients, with a significant decrease in systolic SR even in patients
[119]
without LV hypertrophy [116-118] ; LA strain parameters are associated with atrial fibrillation and stroke and
peak atrial longitudinal strain also showed an inverse correlation with white matter lesions (WML) [120,121] .

Speckle-tracking based echocardiography may also be a non-invasive tool for the detection of myocardial
fibrosis in FD [122,123] . Global longitudinal systolic strain is lower in patients with LGE in cardiac MRI, with a
significant correlation between global longitudinal systolic strain and the amount of LGE; furthermore,
segmental strain values are particularly decreased in the LGE positive basal posterior and lateral
segments [93,110,123] . Moreover, LV, RV, and LA strains are inversely linked to the heart failure functional
class .
[106]

The effect of ERT in myocardial systolic and diastolic strains is still controversial: in a study with agalsidase
β, there was a significant increase in both longitudinal and radial peak systolic SR and systolic strain after 12
months of treatment ; while in another study, in patients treated with ERT for a mean period of 3.1 years,
[124]
there was no change in global systolic longitudinal or circumferential strain . The improvement in systolic
[107]
SR may be influenced by the presence and amount of myocardial fibrosis at ERT initiation, with a study
showing a significant increase in radial systolic SR occurring only in the subgroup of patients without
fibrosis; systolic SR remained essentially unchanged in patients with mild fibrosis, but rather decreased in
[125]
the severe fibrosis subgroup . ERT also seems to improve LA function by an increase in LA peak positive
strain .
[119]

Magnetic resonance imaging
Cardiac MRI plays a critical role in the differential diagnosis of cardiomyopathies and is the diagnostic
standard for assessing global and segmental cardiac morphology and function, with high spatial resolution
[126]
and low observer variability, in patients with FD . In patients under ERT, cardiac MRI can reliably
evaluate its effects on LV mass in FD patients [23,122,124,127-130] .