Persistent pulmonary hypertension in children after apparent resolution of ultrasound-defined pulmonary hypertension associated with bronchopulmonary dysplasia.

To evaluate pulmonary hemodynamics in patients who had been followed up for bronchopulmonary dysplasia (BPD)-associated pulmonary hypertension (PH) in the mid-term by right heart catheterization (RHC). A retrospective study was conducted among 56 patients who were born at a gestational age < 28 weeks during 2018-2020, and the consecutive patients complicated by BPD and ultrasound-defined PH (n = 10, 18%), of whom 7 patients were treated with sildenafil, were examined by RHC in the mid-term follow-up (median age: 25 months [IQR: 19-32]). Ultrasound study at RHC showed improvement in PH as represented by left ventricular end-systolic eccentricity index (median [IQR], 1.05 [IQR: 1.03-1.06] vs. 1.18 [IQR: 1.15-1.33]), pulmonary artery acceleration time (PAAT) (mean ± SD, 97.3 ± 18.2 vs. 55.2 ± 10.1) and a ratio of PAAT to right ventricular ejection time (0.35 ± 0.05 vs. 0.25 ± 0.04) compared with those at 40 weeks of postmenstrual age (PMA) (p < 0.05, respectively). RHC (mean pulmonary artery [PA] pressure: 21 [19-22] mmHg; pulmonary vascular resistance index [PVRi]: 2.63 [1.95-2.94] Wood Units·m²) revealed that 5 infants (50%) had mild PH (21-24 mmHg) and reduced peripheral PAs by pulmonary wedge angiography. The presence of emphysema on chest CT at 40 weeks of PMA and moderate/marked reduction of contrast filling in peripheral PAs on angiography were correlated with increased PVRi (p < 0.05, respectively).

Conclusion: We observed that even after apparent resolution of ultrasound-defined PH, half of patients had catheterization-defined PH and vasculopathy at 2 years of age. These findings warrant long-term follow-up studies of BPD-associated PH.

What is known: • Pulmonary hypertension (PH) is associated with increased mortality in infants with bronchopulmonary dysplasia (BPD). Mortality in patients with BPD-associated PH predominantly occurs within the first 6 months of life and most patients who survive beyond 6 months show resolution of PH on echocardiography by 2 to 3 years of age.

What is new: • Even after the resolution of echocardiography-derived PH in infants with BPD-associated PH in the mid-term, the majority of such patients have abnormal pulmonary vasculature with PH or mildly elevated pulmonary artery pressure on right heart catheterization (RHC), indicating that echocardiography is insufficient and RHC may be necessary to follow up this population of patients.