Pulmonary arterial stiffness indices assessed by intravascular ultrasound in children with early pulmonary vascular disease: prediction of advanced disease and mortality during 20-year follow-up.

Aims: Prognosis in children with pulmonary vascular disease (PVD) is closely linked to right ventricular (RV) failure due to increased RV-afterload. Pulmonary arterial (PA) stiffening is known to occur early in the course of PVD and constitutes a main component of RV-afterload. This study aimed to evaluate the clinical value of PA-stiffness in children with PVD by determining its association with advanced pulmonary arterial hypertension (PAH) and mortality at long-term follow-up.

Methods And Results: Forty-one children with various stages of arterial PVD, defined as mean PA-pressure  ≥20 mmHg and/or pulmonary-to-systemic flow-ratio  ≥1.2, and mean pulmonary capillary wedge pressure  <15 mmHg, underwent cardiac catheterization with intravascular ultrasound (IVUS) imaging between 1994 and 1997 with follow-up until 2015. PA-stiffness indices evaluated were PA-area-compliance (PA-compliance) and PA-area-distensibility (PA-distensibility). During follow-up, advanced PAH was determined by echocardiography and cardiac catheterization. During a median follow-up of 19 years, in 31 (76%) patients PVD had reversed and 10 (24%) had advanced PAH. Six (15%) died due to PVD. In addition to conventional haemodynamics, PA-compliance and PA-distensibility were associated with advanced PAH at long-term follow-up (adjusted OR [95% CI] 0.56 [0.37-0.85] and 0.52 [0.31-0.86]), and mortality (adjusted HR [95% CI] 0.60 [0.41-0.87] and 0.67 [0.49-0.90]). Also in a subgroup of patients with favourable haemodynamics, baseline PA-compliance and PA-distensibility were lower in patients with advanced PAH at follow-up (P  =  0.002 /P  =  0.030).

Conclusion: In children with PVD, PA-stiffness indices assessed by IVUS predict advanced PAH and mortality at long term follow-up. Especially in patients with favourable haemodynamics, assessment of intrinsic PA-stiffness may enhance the prognostication of disease progression and survival.