Fabry disease is a rare genetic disorder that affects the heart and other parts of the body. This study is looking at how a medicine called venglustat affects the heart in people with Fabry disease. Specifically, it examines the left ventricular mass index (LVMI), which measures the size of the heart's left pumping chamber. Participants will be randomly assigned to either take venglustat or continue with their usual treatment, like agalsidase alfa, agalsidase beta, or migalastat, for 18 months. Visits to the study site are needed every 3 to 6 months.

• The study runs up to 4.4 years if participants join the long-term extension.
• To join, participants must be 18 to 65 years old and have Fabry disease with heart enlargement.
• Participants can't have certain health issues, like recent heart attacks or untreated mental health disorders.

Those in the study will help researchers learn more about how to treat heart issues in Fabry disease. Before joining, a signed consent form is required, and individuals must not have certain other health conditions.