Sodium/Glucose Cotransporter-2 Inhibitors (SGLT2i) Therapy in Duchenne Cardiomyopathy

Duchenne muscular dystrophy (DMD) is an X-linked skeletal and cardiac myopathy resulting from a defect in the gene coding for dystrophin. DMD myopathy leads to loss of ambulation, respiratory failure, cardiomyopathy (CM), and premature death. There is no cure, and while gene therapies now have approval, their cardiac effects are largely unstudied. Supportive care advances have decreased death from respiratory failure but have simultaneously unmasked the fully penetrant CM phenotype, which is now the leading cause of death in DMD. Investigators have documented that DMD CM progresses from normal imaging to diastolic dysfunction with subtle strain abnormalities to manifest systolic dysfunction; these changes correspond pathologically with myocardial inflammation and progressive increase in myocardial fibrosis and fibrofatty infiltration. Large areas of fibrofatty replacement visible on cardiac magnetic resonance (CMR) are felt to be irreversible, meaning that for optimal benefit, therapy must begin before these changes have occurred. Guideline-directed medical therapy (GDMT) is increasingly applied in DMD CM care, but individual response to these therapies is suboptimal and often only serves to minimally delay the inevitable progression to heart failure and early death. There is a critical need for the application of new CM therapeutics in DMD. Sodium/glucose cotransporter-2 inhibitors (SGLT2i) have resulted in mortality benefits in adult CM. The mechanism of this beneficial effect is unknown, but several factors translating to DMD suggest that SGLT2i could have potential for DMD CM: 1) improved cardiac energetics and metabolism; 2) improved mitochondrial function and reduced oxidative stress; 3) reduction in inflammation; 4) inhibition of myocardial fibrosis; 5) reduction in sarcoplasmic calcium leak; 6) improved sympathetic overdrive. While the use of SGLT2i in pediatric patients with significant LV dysfunction has become more common, there are many significant unanswered questions. PK data are limited, and many patients are dosed based on glucosuria, which is not a proven method to determine efficacy or exclude side-effects. The potential for earlier therapy in DMD, before irreversible changes, is immense; however, an understanding of appropriate dosing for children with DMD is necessary before this can be achieved.