Follow-up of Myocardial T1 Relaxation Time in Patients With Anderson Fabry Disease (AFD): Impact of Treatment by Agalsidase Alpha (Replagal®)

Anderson Fabry disease (AFD) is an X-linked lysosomal storage disorder caused by a deficiency of the enzyme alpha-galactosidase. AFD can involve various organs and lead to a series of clinical abnormalities. Left ventricular hypertrophy in middle-aged men is one of its life threatening complications. It was shown that pending the absence of myocardial replacement fibrosis, substitution therapy could improve myocardial morphology and function as well as exercise capacity. Today, there is no available marker of the efficacy of the treatment on the heart morphology and function.

The T1 time (or longitudinal relaxation time) is one of the major components of the image formation in Magnetic Resonance Imaging (along with T2 time and proton density). Several techniques have been described to assess the myocardial T1-time.

One of them called MOLLI (Modified Look Locker Inversion Recovery), was made available in research centres by the Siemens company. In a study published in 2013, Sado et al. showed in a series of various conditions (hypertension, AFD, hypertrophic cardiomyopathy, AL amyloidosis, aortic stenosis and healthy volunteers) that a septal T1 below a threshold of 940ms could discriminate AFD patients. No overlap was shown with other conditions in this study. Our experience with T1 mapping supports that finding (even though our threshold could be slightly different), and we could recently detect by MRI a number of AFD patients, some of them with hypertrophy, some others without hypertrophy. The effect of Replagal® on the T1 relaxation time remains unknown.

The purpose of that study was to follow-up the heart morphology, function and myocardial T1 relaxation time in a population of treated/untreated patients.