Clinical impact of mean pulmonary arterial pressure after balloon pulmonary angioplasty for inoperable chronic thromboembolic pulmonary hypertension

Abstract

Background: Balloon pulmonary angioplasty (BPA) improves haemodynamics in patients with inoperable chronic thromboembolic pulmonary hypertension (CTEPH). Previous studies on BPA have set the treatment objective to achieve a mean pulmonary arterial pressure (mPAP) of <30 mm Hg. However, the clinical impact of mPAP after BPA remains unclear. This study aimed to stratify patients according to their mPAP after BPA and evaluate its association with clinical status and long-term outcomes.

Methods: We retrospectively reviewed 304 patients with inoperable CTEPH (median age, 72 (61 to 79) years) who underwent BPA and follow-up right heart catheterisation. Patients were categorised by mPAP after BPA: ≤20, >20-<30 and ≥30 mm Hg groups.

Results: The WHO functional classification, 6 min walk distance and right ventricular ejection fraction were significantly better in the group with a lower mPAP (trend test p=0.007, p<0.001 and p=0.002, respectively). Additionally, the proportions of patients who required pulmonary vasodilators or oxygen therapy were significantly lower in the group with a lower mPAP (trend test p<0.001 and p<0.001, respectively). Across all multivariable models, the mPAP ≥30 mm Hg group had a significantly poorer prognosis compared with the mPAP ≤20 mm Hg group. In contrast, no significant difference was observed between the mPAP ≤20 mm Hg and >20-<30 mm Hg groups.

Conclusions: In patients with CTEPH after BPA, an mPAP of <30 mm Hg was associated with a favourable prognosis, and patients with an mPAP of ≤20 mm Hg presented with better symptoms, exercise capacity, right ventricular function and more withdrawal from oxygen therapy and pulmonary vasodilators. The BPA treatment goal may require individual adaptation.

Keywords: Cardiac Catheterization; Hypertension, Pulmonary; Outcome Assessment, Health Care.

Figure 1. Study flowchart. This study included patients with inoperable CTEPH who underwent BPA and follow-up RHC after final BPA. Patients were classified into three groups according to their mPAP after BPA: groups with an mPAP of ≤20, >20–<30 and ≥30 mm Hg. BPA, balloon pulmonary angioplasty; CTEPH, chronic thromboembolic pulmonary hypertension; mPAP, mean pulmonary arterial pressure; RHC, right heart catheterisation.

Figure 2. Clinical parameters in each group. Comparisons of clinical parameters among the three groups: (A) WHO-FC, (B) 6MWD, (C) plasma BNP levels and (D) RVEF. Data are presented as the median (IQR). BNP, brain natriuretic peptide; mPAP, mean pulmonary arterial pressure; 6MWD, 6 min walk distance; RVEF, right ventricular ejection fraction; WHO-zFC, WHO Functional Classification.

Figure 3. Withdrawal from treatment in each group. Comparisons among the three groups of withdrawal from treatment, including (A) oxygen therapy and (B) pulmonary vasodilators, are shown. mPAP, mean pulmonary arterial pressure.

Figure 4. Prognosis in each group. Unadjusted survival curves of (A) all patients and (B) the three study groups (groups with an mPAP of ≤20, >20–<30 and ≥30 mm Hg) are shown. Patients in the group with an mPAP of ≥30 mm Hg had worse long-term survival than those in the groups with an mPAP of ≤20 and >20–<30 mm Hg. mPAP, mean pulmonary arterial pressure.