Background A small but significant reduction in left ventricular (LV) mass after 18 months of migalastat treatment has been reported in Fabry disease (FD). This study aimed to assess the effect of migalastat on FD cardiac involvement, combining LV morphology and tissue characterisation by cardiac magnetic resonance (CMR) with cardiopulmonary exercise testing (CPET).

Methods Sixteen treatment-naïve patients with FD (4 women, 46.4±16.2 years) with cardiac involvement (reduced T1 values on CMR and/or LV hypertrophy) underwent ECG, echocardiogram, troponin T and NT-proBNP (N-Terminal prohormone of Brain Natriuretic Peptide) assay, CMR with T1 mapping, and CPET before and after 18 months of migalastat.

Results No change in LV mass was detected at 18 months compared to baseline (95.2 g/m² (66.0–184.0) vs 99.0 g/m² (69.0–121.0), p=0.55). Overall, there was an increase in septal T1 of borderline significance (870.0 ms (848–882) vs 860.0 ms (833.0–875.0), p=0.056). Functional capacity showed an increase in oxygen consumption (VO₂) at anaerobic threshold (15.50 mL/kg/min (13.70–21.50) vs 14.50 mL/kg/min (11.70–18.95), p=0.02), and a trend towards an increase in percent predicted peak VO₂ (72.0 (63.0–80.0) vs 69.0 (53.0–77.0), p=0.056) was observed. The subset of patients who showed an increase in T1 value and a reduction in LV mass (n=7, 1 female, age 40.5 (28.6–76.0)) was younger and at an earlier disease stage compared to the others, and also exhibited greater improvement in exercise tolerance.

Conclusion In treatment-naïve FD patients with cardiac involvement, 18-month treatment with migalastat stabilised LV mass and was associated with a trend towards an improvement in exercise tolerance. A tendency to T1 increase was detected by CMR. The subset of patients who had significant benefits from the treatment showed an earlier cardiac disease compared to the others.

Trial registration number NCT03838237.