Abstract Body (Do not enter title and authors here): Background: Idiopathic/heritable pulmonary arterial hypertension (I/H-PAH), a disease with poor prognosis, often faces diagnostic delays due to nonspecific initial symptoms. In Japan, school ECG screening, performed in every 3 years for all students, identifies 41% of school-aged I/H-PAH patients; these typically show elevated pulmonary artery pressure (PAP) but have minimal symptoms (WHO-FC I/II) and preserved RV function. In this disease, the duration from the appearance of pulmonary vascular lesions to PH manifestation and the subsequent onset of RV failure are unknown.
Objective: To address the precise pathological trajectory leading to PH manifestation, PH-related ECG findings at diagnosis (Dx) and pre-Dx in pediatric PAH patients were investigated utilizing Japan's school ECG screening system.
Methods: Observational study of I/H-PAH patients (6-18 years), newly diagnosed 2005-2020, in Japanese pediatric cardiology teaching hospitals. School ECGs at/pre Dx were evaluated for PH-related findings (R≥1.5mV in V1, RV strain, Q in V1, IRBBB, inverted T waves) according to the criteria from the Japanese Society of Pediatric Cardiology and Cardiac Surgery.
Results: In the survey, 118/143 institutions (82.5%) responded; 45 (38%) of those reported cases. 88 patients (51M, 37F; mean age 10.7y) were analyzed. Mode of detection of PAH were school ECG screening (n=36), symptoms (44), family history (5), and incidental findings (3). Compared to nonscreening group, the school screening group had higher proportion of WHO-FC I/II (91% vs 57%, p<.01) and lower plasma BNP (20 vs 102 pg/mL, p<.01), with comparable mean PAP (48 vs 55 mmHg, p=.65) and PVRI (12.1 vs 15.8 WU×m², p=.38). PH-related ECG findings at Dx (n=87), which were present in 93% of all patients, were largely comparable between the groups (95% vs 91, p=.68), with the exception of higher prevalence of Q waves in V1 in the nonscreening (31% vs 15, p<.05) and R≥1.5mV in V1 in the screening group (59% vs 30, p<.05). Crucially, among 35 pre-Dx ECGs, PH-related abnormalities were observed in 77% (10/13) of those taken within 2 years of Dx, versus only 14% (3/22, p<.01) of those taken >2 years prior.
Conclusion: Pre-Dx ECG analysis indicates PH-related findings can appear up to 2 years before symptom manifestation, suggesting a 1-2 year window of established PH with minimal symptoms in many pediatric patients. This highlights the potential for earlier diagnosis by performing ECG screening at even shorter intervals.