Understanding Mortality Risk in Pediatric Pulmonary Arterial Hypertension

A new study has found that the cause of a child’s pulmonary arterial hypertension (PAH) might be important in determining risk of mortality.

The study, published this month in Transplantation Proceedings, looked at various factors used in an internationally developed risk stratification strategy to assess which ones had evidence of being significant in determining a child’s prognosis from the deadly disease.

It found those with idiopathic PAH had a higher risk than those whose PAH was associated with congenital heart disease (CHD) and other etiologies. It also determined that higher resistance to blood flow from the pulmonary artery to the left atrium was connected to risk. However, the authors were unable to determine whether other factors, taken alone or in combination, affected risk.

Children with PAH have stiff pulmonary arteries, forcing the heart to work harder to pump blood to the lung, leaving the child out of breath and at risk of failure of the right ventricle. New target therapies have decreased mortality and morbidity in recent decades, but given low pediatric patient numbers in studies, devising treatment strategy has been challenging, the authors wrote.

Researchers from Hungary used records from 58 patients with PAH treated between 1995 and 2019. They found that patients with idiopathic PAH had increased mortality risk compared to those whose disease was congenital. There were 12 patients with idiopathic disease in the study group; 32 had PAH associated with CHD.

They also found that patients with higher pulmonary vascular resistance index had significantly increased risk.

The researchers additionally looked at other factors, including demographics, World Health Organization functional class (WHO FC) as well as various signs of right ventricular failure from echocardiography and cardiac catheterization.

The authors found that clinical parameters such as WHO functional state (P = .0866), clinical evidence of right ventricular failure (P = .2760), or growth retardation, (P = .630) had no significant prognostic value. Nor did the presence of pathology in echocardiograms such as right atrium (RA)/right ventricle (RV) enlargement, reduced left ventricle (LV) size, increased RV/LV ratio, reduced tricuspid annular plane systolic excursion, and pericardial effusion (P = .0576). Due to low sample size, however, the authors cautioned against considering these finds as major evidence against their effect and favored further study.

The authors also examined several risk factors in combination, but again found no significant impact on survival.

Records used in the study showed a 29% mortality rate over a 5.4-year span. Median age of diagnosis was 4.2 years.

The risk stratification strategy examined in the study was assembled by the Pediatric Task Force of the 5th World Symposium on Pulmonary Hypertension in 2019 using available evidence to determine at initial diagnosis which child patients were at higher or lower risk levels. Since the physical and financial burden is high for the aggressive combination therapy used for high-risk patients—which includes intravenous or subcutaneous prostacyclin treatment—making such evaluations of risk is critical.

The adult risk stratification is inappropriate for children due to differences in cause, the authors said. For example, 4%-12% of adults had PAH associated with congenital heart disease, compared with 36% for children.

Reference

Ablonczy L, Ferenci T, Somoskövi O, et al. Prognostic value of early risk stratification in pediatric pulmonary arterial hypertension. Transplant Proc. 2021;S0041-1345(21)00081-6. Published online February 20, 2021. doi:10.1016/j.transproceed.2021.01.047.