Pediatric and Adolescent Pulmonary Hypertension: What Is the Risk of Undergoing Invasive Hemodynamic Testing?

ediatric pulmonary hypertension (PH) is a complex disease associated with significant morbidity and mortality.Important pediatric PH subtypes include the following: idiopathic pulmonary arterial hypertension (IPAH), PH associated with congenital heart disease, and PH secondary to lung disease.PH-targeted medications have led to improved survival; in children who did not respond to a calcium channel blocker at heart catheterization (HC), the 4-year survival without directed pulmonary arterial hypertension therapy was poor (35%) 1 compared with a 5-year survival of 84% in children receiving PH-specific medical therapy. 2 Children with PH are considered high risk for invasive procedures and surgery, given that life-threatening complications, such as PH crisis, can occur.In PH crisis, the pulmonary vascular resistance (PVR) immediately increases to a point at which pulmonary artery pressure exceeds systemic arterial pressure, resulting in reduced pulmonary perfusion and subsequent decline in cardiac output, followed by hypoxia and biventricular failure.Common precipitants of PH crisis are as follows: infection, malfunction of pump/catheter infusing prostacyclin analog therapy, pulmonary embolism, arrhythmia, trauma, anemia, and worsening hypoxia.Hemodynamic assessment with HC is the standard tool used to evaluate hemodynamics at presentation and in reassessment after targeted therapy. 3The overall adverse event (AE) rate with pediatric HC is relatively low at 0.1% 4 ; however, HC in children with PH is substantially higher, with cardiac arrest occurring in 4% to 6%. 5,6 Both single-center and pooled registry data have shown that children with PH undergoing HC have a high risk of major AEs (3.5%-6.2%)and death (0.2%-1.4%). 4,6-14However, there are limited data identifying important risk factors for major AE and death in the pediatric PH population.Younger age, preprocedural systemic vasodilator use, renal dysfunction, higher mean pulmonary artery (mPA) pressure, single ventricle anatomy, and cardiac operation during the same admission have all been shown to be important risk factors for AE in pediatric and adolescent HC (Table ).Prior studies have several limitations: small individual center volumes are not powered to be able to determine cutoff values for risk factors, databases that require consent are prone to recruitment bias, administrative databases have limited clinical data, and disease-specific registries may overrepresent a specific type of disease.To more specifically estimate individual risk on the basis of PH severity, O'Byrne and colleagues, in this issue of Journal of the American Heart Association (JAHA) query the Improving Pediatric and Adult Congenital Treatment Registry to determine the risk of catastrophic AEs in children and adolescents with PH undergoing HC. 15 A secondary analysis was undertaken to determine if PH disease severity affects individual AE risk and also to determine the degree to which hospital PH-HC experience affects AE risk.In patients 0 to 21 years of age, there were 8111 procedures (7729 subjects; 77 centers) between the years 2011 and 2015 (median age, 3 years [interquartile range, 0-12 years]; and median PVR Index, 4.1 WU/m 2 [interquartile range, 2.6-6.5 WU/m 2 ]).Subjects were included if they had ≥1 of following diagnostic codes or met ≥1 of the following criteria: IPAH, pulmonary vascular obstructive disease, mPA pressure >25 mm Hg, or PVR Index >4 WU/m 2 .Exclusion criteria included the following: elevated mPA pressure without elevated PVR Index attributable to leftto-right shunt, fixed anatomic stenosis undergoing PA angioplasty or pulmonary valvuloplasty, centers with <10 PH catheterizations, patients receiving extracorporeal membrane oxygenation or left ventricular assist device therapy, and those with single-ventricle disease.The most common