Endothelin inhibitors lower pulmonary vascular resistance and improve functional capacity in patients with Fontan circulation

Objectives

To evaluate the effects of endothelin inhibitors (ERAs) on hemodynamic and functional parameters in patients post-Fontan procedure with high pulmonary vascular resistance (PVR).

Methods

Among our cohort of patients with Fontan circulation, 8 children, 8 adolescents, and 8 adults had PVR ≥2 WU*m². These patients were treated with ERAs (minors with bosentan, adults with macitentan) and reevaluated after 6 months. Pre- and posttreatment hemodynamic variables were assessed by cardiac catheterization. Functional capacity was evaluated by cardiopulmonary exercise testing (CPET). Our primary endpoint was to obtain a reduction of PVR; the secondary endpoint was to obtain an improvement of functional capacity.

Results

Under treatment, New York Heart Association class improved for adolescents and adults. PVR decreased (P = .01) in all groups: in children from the median value 2.3 (interquartile range 2.0-3.1) to 1.9 (1.4-2.3) WU*m², in adolescents from 2.3 (2.1-2.4) to 1.7 (1.4-1.8) WU*m², and in adults from 2.8 (2.0-4.7) to 2.1 (1.8-2.8)WU*m². In 71% of patients, PVR fell to less than 2 WU*m². Cardiac index increased in adolescents from 2.6 (2.4-3.3) to 3.6 (3.4-4.3) L/min/m², P = .04, and in adults from 2.1 (2.0-2.3) to 2.8 (2.3-4.7) L/min/m², P = .03. CPET showed that only adolescents displayed a significant functional improvement. Anaerobic threshold improved from 17 (13-19) to 18 (13-20) mL/kg/min, P = .03; oxygen consumption and VO₂ max increased from 1.3 (1.0-1.6) to 1.7 (1.1-1.9) L/min, P = .02 and from 25 (21-28) to 28 (26-31) L/min, P = .02, respectively. Oxygen pulse increased from 7.9 (5.7-10.4) to 11.2 (8.2-13.0) L/beat, P = .01.

Conclusions

This is the first study that assesses by cardiac catheterization and CPET the effects of ERA in patients with Fontan circulation with increased PVR. These results suggest that ERAs might provide most pronounced hemodynamic and functional improvement in adults and adolescents.