Cao, Jacob

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.

Background Exercise cardiac catheterization is the gold standard for diagnosing diastolic dysfunction and impaired pulmonary reserve in patients with Fontan circulation. The diagnostic value of noninvasive parameters is unclear. Methods Patients who underwent simultaneous exercise hemodynamic evaluation and peripheral venous pressure (PVP) measurement were included. Echocardiographic surrogates for ventricular filling pressure were compared with invasive measures. Diastolic dysfunction was defined invasively as either resting pulmonary artery wedge pressure ≥12 mm Hg or exercise pulmonary artery wedge pressure >20 mm Hg. Results Twenty‐nine patients were included. Age at catheterization was 34±9 years. Atrioventricular valve systole‐to‐diastole duration ratio (S/D) and resting PVP were significant predictors of resting pulmonary artery wedge pressure (S/D: β=0.71 per 0.1 S/D [95% CI, 0.16–1.25]; P =0.01; PVP: β=0.68 per mm Hg [95% CI, 0.41–0.96]; P <0.001). By contrast, resting PVP was a predictor of diastolic dysfunction, whereas S/D was not. Based on these data, we proposed a 2‐tier assessment algorithm with the first tier considering resting PVP ≤15 mm Hg and S/D ≤1.1 and the second tier considering exercise PVP ≤25 mm Hg in those with 1 elevated resting parameter. This algorithm showed a positive predictive value of 88% (95% CI, 47%–100%), a negative predictive value of 90% (95% CI, 70%–99%), a sensitivity of 78% (95% CI, 40%–97%), and a specificity of 95% (95% CI, 75%–100%). Exercise PVP indexed to peak oxygen consumption also predicted invasively measured exercise pulmonary vascular resistance index (β=0.36 WU·m 2 per mm Hg/100 mL per min [95% CI, 0.08–0.64]; P =0.01). Conclusions This study presents a simple, noninvasive approach for evaluating diastolic function and pulmonary vascular reserve in patients with a Fontan circulation.