What's new about angiotensin receptor blocker (ARB) therapy for Marfan syndrome: A narrative review.

Marfan syndrome (MFS) is a genetic disorder caused by mutations in the FBN1 gene, which encodes fibrillin-1, a crucial protein involved in the structure of elastic fibers and the regulation of transforming growth factor-beta (TGF-β) bioavailability. Defective fibrillin-1 disrupts these fibers, leading to skeletal, ocular, and cardiovascular abnormalities. A key pathological mechanism in MFS is excessive TGF-β signaling, which has been targeted by angiotensin receptor blocker (ARB) therapies such as losartan, demonstrating potential in restoring normal phenotypes in experimental models. The aim of this narrative review was to highlight findings that demonstrate the potential of ARBs for MFS. Aortic root dilation is a defining feature of MFS. Studies have shown that losartan therapy significantly reduces the dimensions of the aortic root and sinotubular junction in children. However, its long-term efficacy remains uncertain. Beyond its primary effects on the aorta, chronic losartan treatment enhances endothelial function by promoting nitric oxide-mediated vasodilation, which may help prevent aortic root widening. The drug's effects are partly attributed to its metabolites, EXP3174 (an angiotensin II type 1 receptor [AT1] antagonist) and EXP3179 (an NADPH oxidase inhibitor). Overexpression of NADPH oxidase in MFS contributes to vascular dysfunction, and EXP3179 mitigates aortic vasoconstriction. Given these mechanisms, ongoing research explores the potential of AT1 receptor antagonists as therapeutic agents in MFS, aiming to improve vascular health and long-term patient outcomes.