Clinical Utility of Stroke Volume Index in Children with Idiopathic and Heritable Pulmonary Arterial Hypertension.

To determine the prognostic value of stroke volume index (SVi) in children with idiopathic and heritable pulmonary arterial hypertension (PAH). A retrospective study was performed to assess the prognostic value of SVi evaluated by right heart catheterization, and adverse outcomes (AE: lung transplant and cardiac death) in 103 incident pediatric patients with PAH. During catheterization, cardiac index was obtained using Fick method and SVi was determined by dividing cardiac index by heart rate. During follow-up period, 23 of 103 (22%) patients had AE. There were significant differences in hemodynamic parameters at baseline including SVi (median 35.6 vs. 29.1ml/m2, p < 0.05) between patients with and without AE. When SVi cutoff value of 33 ml/m2 for prediction of AE was evaluated by Receiver-Operating Characteristic curve, the area under the curve was 0.75. Forty-two with lower SVi (≤ 33 ml/m2) had 16 events (38%) and the remaining 61 patients with higher SVi had 7 events (11%) during follow-up (p < 0.05). Cumulative event-free survival rate was significantly lower when SVi was ≤ 33 ml/m2 (p < 0.05). SVi was a predictor of death or lung transplantation (HR = 0.92; 95% confidence interval 0.89-0.97; p < 0.05). Lower SVi was associated with higher risk of cardiac and lung transplantation in pediatric patients with idiopathic and heritable PAH. SVi appears to add prognostic information and may be useful for risk stratification.