Opp, Derek N.

Background Patients with single-ventricle physiology are often palliated with the Fontan operation, which may involve the creation of a fenestration. We aimed to evaluate differences in cardiopulmonary exercise test (CPET) performance between patients with fenestrated and non-fenestrated Fontan circulation. Methods Patients with a Fontan circulation referred to CPET between 2006 and 2024 were included and were categorised based on their fenestration status at the time of CPET. Logistic regression analyses were performed to assess the impact of fenestration on peak oxygen consumption (VO 2 ), and Cox proportional hazard to evaluate the impact of fenestration on cardiovascular outcomes (death, heart transplant and Fontan-related hospitalisation). Results Of the 184 patients, 141 were classified as non-fenestrated and 43 as fenestrated. The minute ventilation-carbon dioxide production (V E /VCO 2 slope) was higher in the fenestrated (36.9±7.9) versus (33.2±6.2; p=0.009) in the non-fenestrated group. There was no significant difference in predicted VO 2 between groups (non-fenestrated 51.9%±14.4 vs 51.3%±15.6; p=0.7). Resting oxygen saturation was higher in the non-fenestrated group (93%±4.7 compared with fenestrated group 90.1%±5; p<0.001). Fontan fenestration was not significantly associated with the composite outcome; older patient age at the time of the CPET, cirrhosis and ventricular ejection fraction <40% were significantly associated with higher risk, while higher resting systolic blood pressure, left ventricular morphology and higher predicted peak VO 2 were protective. Conclusions The increased hypoxia and reduced ventilatory efficiency associated with Fontan fenestration offset any potential benefits, resulting in similar exercise performance between the groups. Fontan fenestration was not significantly associated with cardiovascular outcomes.

Background: Many children born with single ventricle physiology are palliated with Fontan operation, which may include a fenestration creation. This has been demonstrated to improve short-term outcomes after surgery. Reduced exercise capacity has been shown to be a predictor of prognosis in Fontan patients. Aim: We sought to compare cardiopulmonary exercise test (CPET) data between fenestrated and non-fenestrated Fontan patients. Methods: We conducted a retrospective cohort study of 185 patients referred for CPET from 2011 to 2024. Patients with complete CPET data were included. Type of Fontan, comorbidities, and echocardiogram data were ascertained electronically. Patients were divided into 2 different groups according to the fenestration patency. Fisher’s exact test or chi-square was used to compare categorical variables. T-test and Turkey-Kramer were used to compare continuous variables. Adjustment using General Lineal Models procedure were used to identify any confounder that could affect the results. P value <0.05 was considered significant. Results: 142 patients were classified in the non-fenestrated (NF) group, and 43 in the fenestrated group (FF). Baseline characteristics of both groups are shown in Table 1. From the evaluated CPET variables, the minute ventilation-carbon dioxide production (VE/VCO2) was higher in the FF (p=<0.001), and oxygen saturation at peak exercise (SatO2) was lower in this group (p= <0.001) (Figure 1). There was no significant difference between peak oxygen consumption (VO2) between groups. When adjusted by comorbidities only VE/VCO2 nadir, slope and peak SatO2 were statistically significant different between groups (Table 2). Conclusion: Ventilatory variables showed significant differences when fenestration was presented, secondary to V-Q mismatch from increased right to left shunt. Despite the theoretical advantage of increased cardiac output from Fontan fenestration, exercise performance was similar between both groups.

Abstract Aims The effects of obesity on Fontan haemodynamics are poorly understood. Accordingly, we assessed its impact on exercise invasive haemodynamics and exercise capacity. Methods and results Seventy-seven adults post-Fontan undergoing exercise cardiac catheterization (supine cycle protocol) were retrospectively identified using an institutional database and categorized according to the presence of obesity [body mass index (BMI) &gt; 30 kg/m2] and overweight/normal BMI (BMI ≤ 30 kg/m2). There were 18 individuals with obesity (BMI 36.4 ± 3 kg/m2) and 59 with overweight/normal BMI (BMI 24.1 ± 3.6 kg/m2). Peak oxygen consumption (VO2) on non-invasive cardiopulmonary exercise testing was lower in patients with obesity (15.6 ± 3.5 vs. 19.6 ± 5.8 mL/kg/min, P = 0.04). At rest, systemic flow (Qs) [7.0 (4.8; 8.3) vs. 4.8 (3.9; 5.8) L/min, P = 0.001], pulmonary artery (PA) pressure (16.3 ± 3.5 vs. 13.1 ± 3.5 mmHg, P = 0.002), and PA wedge pressure (PAWP) (11.7 ± 4.4 vs. 8.9 ± 3.1 mmHg, P = 0.01) were higher, while arterial O2 saturation was lower [89.5% (86.5; 92.3) vs. 93% (90; 95)] in obesity compared with overweight/normal BMI. Similarly, patients with obesity had higher exercise PA pressure (29.7 ± 6.5 vs. 24.7 ± 6.8 mmHg, P = 0.01) and PAWP (23.0 ± 6.5 vs. 19.8 ± 7.3 mmHg, P = 0.047), but lower arterial O2 saturation [82.4 ± 7.0% vs. 89% (85; 92), P = 0.003]. Conclusion Adults post-Fontan with obesity have worse aerobic capacity, increased Qs, higher filling pressures, and decreased arterial O2 saturation compared with those with overweight/normal BMI, both at rest and during exercise, mirroring the findings observed in the obesity phenotype of heart failure with preserved ejection fraction. Whether treating obesity and its cardiometabolic sequelae in Fontan patients will improve haemodynamics and outcomes requires further study.