Acute Vasodilator Response in Pediatric Pulmonary Arterial Hypertension: Current Clinical Practice From the TOPP Registry.

BACKGROUND In pulmonary arterial hypertension (PAH), acute vasodilator response testing (AVT) is considered important to identify adult patients with favorable prognosis using calcium-channel blocker (CCB) therapy. However, in pediatric PAH, criteria used to identify acute responders and CCB use are insufficiently studied. OBJECTIVES This study sought to describe current clinical practice of AVT and subsequent treatment decisions in pediatric PAH. METHODS From January 2008 to May 2013, 529 consecutive children with confirmed pulmonary hypertension were enrolled in an international registry. We analyzed those children with evaluable AVT. RESULTS Of 382 children with evaluable AVT, 212 had idiopathic/familial PAH (IPAH/FPAH) and 105 had PAH associated with congenital heart disease (PAH-CHD). In 70% of the patients, AVT was performed using inhaled nitric oxide; other agents were used in the remaining patients. In IPAH/FPAH patients, 78 (37%) patients were acute responders according to their physician, 62 (30%) according to REVEAL (Registry-to-Evaluate-Early-And-Long-term PAH disease management)-pediatric criteria, and 32 (15%) according to Sitbon criteria. For PAH-CHD patients, the numbers of AVT responders were 38 (36%), 14 (13%), and 7 (7%) respectively. Correlation between AVT responder status as judged by the treating physician and by published response criteria was poor. Moreover, of the IPAH/FPAH patients judged by the treating physician as acute responders, only 23% were treated with CCB without additional PAH-targeted therapy. The Sitbon criteria selected patients with better prognosis who had excellent outcome when treated with CCB. CONCLUSIONS The current practice of identifying responders to AVT and subsequent treatment with CCB therapy demonstrated large discrepancies with current international guidelines. Also, in pediatric IPAH, the Sitbon criteria are the criteria of choice to identify patients with excellent survival when treated with CCB therapy.