Nakata index above 1500 mm²/m² predicts death in absent pulmonary valve syndrome

OBJECTIVES: Absent pulmonary valve syndrome is a rare congenital heart disease with severe airway compression due to dilatation of the pulmonary arteries (PAs). We investigated risk factors for death and prolonged mechanical ventilation (>7 days) and a threshold PA size for these outcomes. METHODS: This retrospective 2-centre cohort study included 68 patients with complete repair between January 1996 and December 2015. RESULTS: Median age at repair was 3.9 months (1.3-8.7 months), and median weight was 5 kg (4-7 kg). The mortality rate before hospital discharge was 12%, and the mortality rate at last follow-up was 19%. In multivariable analysis, risk factors for death were higher Nakata index [hazard ratio (HR) 1.001, 95% confidence interval (CI) 1.001-1.002; P < 0.001] and lower SpO₂ (HR 1.06, 95% CI 1.02-1.09; P = 0.002). The accuracy of the Nakata index to predict death was excellent (area under the curve at 6 months: 0.92; P = 0.010). A Nakata index above 1500 mm²/m² predicted mortality at 6 months with a sensitivity of 98% and a specificity of 82%. Twenty-five patients (37%) had prolonged mechanical ventilation. The only multivariable risk factor for prolonged ventilation was lower weight at repair (odds ratio 2.9, 95% CI 1.3-6.7; P = 0.008). Neither PA plasty nor the LeCompte manoeuvre had a protective effect on mortality or prolonged ventilation. A Nakata index above 1500 mm²/m² remained a risk factor for mortality (P = 0.022) in patients who had a PA plasty or the LeCompte manoeuvre. CONCLUSIONS: In patients with absent pulmonary valve syndrome, the Nakata index predicts mortality with a cut-off of 1500 mm²/m². Lower weight at repair is the only multivariable risk factor for prolonged ventilation. Neither PA plasty nor the LeCompte manoeuvre had a protective effect on these outcomes.