# Clinical improvement of protein-losing enteropathy after SGLT2 inhibitor therapy in an adult with failing Fontan circulation: a case report

## TL;DR

A patient with a failing Fontan circulation and protein-losing enteropathy showed clinical improvement after treatment with SGLT2 inhibitors.

## Contribution

Demonstrates potential therapeutic benefit of SGLT2 inhibitors in managing Fontan failure complicated by protein-losing enteropathy.

## Key findings

- SGLT2 inhibitor therapy led to reduced ascites and stabilized serum protein levels in a patient with failing Fontan circulation.
- Magnetic resonance lymphoscintigraphy revealed lymphatic congestion and leakage, supporting the role of lymphatic dysfunction in the patient's condition.
- Conventional treatments failed to manage the patient's condition before SGLT2 inhibitor therapy was initiated.

## Abstract

Sodium–glucose cotransporter 2 inhibitors (SGLT-2i) have proven benefits in patients with biventricular heart failure; however, their role in patients with univentricular physiology and failing Fontan circulation (FC) remains largely unexplored.

A 21-year-old male with failing FC, preserved ejection fraction, and protein-loosing enteropathy (PLE) presented to our Adult Congenital Heart Disease Unit for evaluation. Born with a L-transposition of the great vessels with an interventricular septal defect and antero-superior rudimentary chamber, he underwent a Fontan completion at age 5. Since he was 16 years old, he had multiple admissions for FC failure complicated by PLE and ascites, which did not respond to conventional treatments including diuretics, corticosteroids, albumin, and immunoglobulin infusions. Despite the stenosis of the extracardiac conduit, treated by the placement of a covered stent and a further conduit balloon dilation and stenting in a stent procedure performed after 3 years, the patient continued to experience ascites and hypoalbuminemia. To better understand the extent of his lymphatic dysfunction, magnetic resonance lymphoscintigraphy was performed. The study showed significant lymphatic congestion, with leakage into the duodenal lumen and prominent stasis in the thoracic duct. Based on these findings, therapy with SGLT-2i was initiated. Over the following 18 months, there was marked clinical improvement with a reduction in ascites and stabilization of serum protein and albumin levels.

This case highlights the potential benefit of SGLT-2i in managing Fontan failure complicated by PLE. Multicenter studies are needed to further investigate the efficacy, safety, and mechanism of action of SGLT-2i in this unique patient population.