Researchers proposed that syncope in some children with pulmonary arterial hypertension (PAH) could be caused by acute pulmonary vasoconstriction to an adverse stimuli, according to a study published in ERJ Open Research. 

Patients with PAH can sometimes have a vague presentation, which limits the pool of therapeutic resources that can be used to improve their condition. Syncope, however, is one of the more recognized symptoms in PAH. It is thought to occur due to right ventricular dysfunction and cardiac output insufficiency, especially during periods of exertion. 

“Based on these findings, studies of children with PAH list syncope as a high-risk factor, with significant implications for functional classification and treatment selection,” the authors wrote. 

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They hypothesized that children with syncope have a greater likelihood of demonstrating acute vasoreactivity during vasodilator testing compared with children without syncope. 

Read more about PAH etiology

Linder and colleagues recruited children who presented at the Columbia University Medical Center in New York to be treated for PAH between January 2005 and October 2018. Only patients with Group 1 PAH, defined as mean pulmonary artery pressure 25 mmHg or more, pulmonary capillary wedge pressure 15 mmHg or less, and pulmonary vascular resistance at or greater than 3 WU, were included in the study. 

The research team collected information from participants relating to their World Health Organization functional class, brain natriuretic peptide and/or N-terminal pro-brain natriuretic peptide, imaging, hemodynamics, treatment, date of diagnosis, and last follow ups as of September 2021. 

The results demonstrated that patients with syncope had greater rates of acute vasodilator testing response upon diagnosis compared with patients without syncope. In addition, the cohort of children who did experience syncope had excellent outcomes, with 100% survival throughout the follow-up period. This means that syncopal episodes in some children may reflect acute pulmonary vasoconstriction to adverse stimulus and are therefore not indicative of poorer outcomes. 

“Larger prospective studies are warranted to further assess syncope as a marker for a vasoreactive phenotype with implications for treatment and long-term outcomes,” the authors concluded. 


Linder AN, Hsia J, Krishnan SV, Rosenzweig EB, Krishnan US. Vasoreactive phenotype in children with pulmonary arterial hypertension and syncopeERJ Open Res. 2022;8(4):00223-2022. doi:10.1183/23120541.00223-2022