Objective:

To assess the impact of obesity on exercise invasive haemodynamics and exercise capacity in adults post-Fontan, highlighting its significance in clinical management.

Key Findings:

• Patients with obesity had lower peak VO2 (15.6 ± 3.5 vs. 19.6 ± 5.8 mL/kg/min, P = 0.04), indicating reduced exercise capacity.
• At rest, systemic flow was higher in obesity (7.0 vs. 4.8 L/min, P = 0.001), suggesting altered haemodynamics.
• Obesity was associated with higher pulmonary artery pressure (16.3 vs. 13.1 mmHg, P = 0.002) and wedge pressure (11.7 vs. 8.9 mmHg, P = 0.01), which may impact clinical outcomes.
• Arterial O2 saturation was lower in obesity (89.5% vs. 93%, P < 0.05), indicating potential oxygenation issues.
• During exercise, obesity correlated with higher pulmonary artery pressure (29.7 vs. 24.7 mmHg, P = 0.01) and lower arterial O2 saturation (82.4% vs. 89%, P = 0.003), emphasizing the need for targeted interventions.

Interpretation:

Adults post-Fontan with obesity exhibit worse aerobic capacity and altered haemodynamics compared to those with normal/overweight BMI, indicating potential implications for management and treatment strategies.

Limitations:

• Retrospective design limits causality inference and may introduce biases.
• Small sample size may affect generalizability of findings.
• Lack of long-term follow-up data on outcomes limits understanding of the chronic effects of obesity.

Conclusion:

Further studies are urgently needed to explore whether addressing obesity and its sequelae can improve haemodynamics and outcomes in Fontan patients.