Adults with Fontan circulation: prognostic value of exercise pulmonary vascular resistance index

Abstract

Background and aims: Decrease in pulmonary vascular resistance (PVR) during exercise confers favourable prognosis in biventricular physiology, but its role in Fontan circulation remains unknown. This study aimed to evaluate the prognostic value of PVR index (PVRI) response to exercise in adults post-Fontan palliation.

Methods: Retrospective cohort of 88 adults (age ≥18 years) post-Fontan undergoing exercise (supine cycling) cardiac catheterization. Patients were categorized into absence (n = 23) or presence (n = 65) of exercise-induced reduction in PVRI. The clinical endpoint was a composite of death or transplantation.

Results: Age at catheterization was 32.2 ± 8.8 years, and 45.5% were female. Resting and exercise PVRI were 1.9 ± 0.9 and 1.2 (interquartile range [IQR] 0.8-2.1) WU·m2, respectively. Clinical, biochemical and echocardiographic parameters were not associated with PVRI response to exercise. During a follow-up of 2.2 ± 1.4 (IQR 1.2-2.6) years, resting PVRI was not associated with the clinical endpoint (hazard ratio [HR] 0.95 per WU·m2, 95% confidence interval [CI] 0.52-1.74; P = 0.86), whereas exercise PVRI was (HR 2.15 per WU·m2, 95% CI 1.24-3.73; P = .007). Exercise PVRI remained predictive of outcomes after adjusting for exercise pulmonary artery wedge pressure (HR 2.08 per WU·m2, 95% CI 1.19-3.62; P = .01) or clinical risk factors individually. Two-year event-free survival was lower in the no PVRI reduction than in the reduction group (67% vs 95%; P < .001).

Conclusions: In adults post-Fontan, PVRI response to exercise is a robust predictor of clinical outcomes and offers additive prognostic information beyond resting invasive haemodynamic data and clinical risk factors, underscoring the importance of invasive exercise testing in this population.

Keywords: Exercise testing; Fontan circulation; Pulmonary vascular resistance index.