Patient characteristics
| Syncope | Non-syncope | p-value | |
| Subjects n | 47 | 122 | |
| Sex, female | 29 (62) | 66 (54) | 0.40 |
| Median age years | 7.9 (0.4–19) | 3.0 (0–18.4) | 0.002 |
| Symptoms | |||
| Dyspnoea on exertion | 43 (91) | 118 (97) | 0.08 |
| Chest pain | 20 (43) | 30 (25) | 0.022 |
| Failure to thrive | 9 (19) | 40 (33) | 0.075 |
| Fatigue | 34 (72) | 57 (47) | 0.003 |
| PAH classification | |||
| Idiopathic PAH | 36 (76) | 37 (30) | <0.00001 |
| Heritable PAH | 3 (6) | 2 (2) | 0.13 |
| APAH-CHD | 10 (21) | 79 (65) | <0.00001 |
| Repaired | 5 (50) | 53 (67) | 0.29 |
| Unrepaired | 5 (50) | 26 (33) | |
| APAH-CTD | 1 (2) | 4 (3) | 1 |
| APAH–portal hypertension | 0 | 2 (1) | 1 |
Data are expressed as median (range) or n (%) unless indicated otherwise. Bold p-values represent statistically significant differences. PAH: pulmonary arterial hypertension; APAH: associated pulmonary hypertension; APAH-CHD: PAH associated with congenital heart disease; APAH-CTD: PAH associated with connective tissue disease.