Assessment of perfusion on ventilation/perfusion scan after balloon pulmonary angioplasty in chronic thromboembolic pulmonary hypertension: expert opinion versus guidance by reference chart

Abstract

Objective: Balloon pulmonary angioplasty (BPA) is frequently used in chronic thromboembolic pulmonary hypertension (CTEPH)/chronic thromboembolic pulmonary disease (CTED). Nevertheless, noninvasive pulmonary perfusion imaging after BPA is scarce. In this study, change in perfusion on ventilation/perfusion (V/Q) scan after BPA was assessed and correlated with clinical outcomes.

Methods: Retrospectively, all consecutive patients with CTEPH/CTED patients who completed BPA and received planar V/Q scans baseline and 6 months follow-up were included. Perfusion was evaluated using gestalt interpretation and semiquantitative calculation of the pulmonary vascular obstruction (PVO) index, with obligatory use of the lung segment reference chart. Interobserver variability was assessed for both methods, and the correlation between PVO index and clinical parameters was tested.

Results: Thirty-three patients with CTEPH/CTED (mean age: 60.4 ± 14.7 years, 70% female) underwent 127 BPA procedures. Gestalt interpretation showed improved perfusion in 79% of all patients, and PVO index decreased significantly compared with baseline (45 ± 15-35 ± 15%; P < 0.001). The gestalt method showed a weak level of agreement ( k = 0.32; P = 0.06), and the PVO method showed a moderate to strong reliability ( R2 : 0.71, P < 0.001). The PVO index showed a significant ( P < 0.001) but weak correlation with log N-terminal probrain natriuretic peptide, mean pulmonary artery pressure, and pulmonary vascular resistance ( R2 : 0.26, 0.24, and 0.18, respectively).

Conclusion: Perfusion on V/Q scan significantly improved after BPA in patients with CTEPH/CTED. Semiquantitative calculation of PVO was more reliable in comparison to gestalt interpretation, however, clinical parameters showed only a weak correlation with the PVO index.

Keywords: balloon pulmonary angioplasty; chronic thromboembolic pulmonary hypertension; ventilation/perfusion scintigraphy.

Fig. 1

Lung segment chart. LPO, left posterior oblique; RPO, right posterior oblique.

Fig. 2

Perfusion images before (a) and after (b) BPA. PVO index was 61% before and 32% after BPA. PVO calculation before BPA: 1 – [left superior lobe (0.13 × 0.75) + left inferior lobe (0.20 × 0.50) + lingula (0.12 × 0.25) + right superior lobe (0.18 × 0.25) + right inferior lobe (0.25 × 0.25) + right middle lobe (0.12 × 0.50)]. PVO calculation after BPA: 1 – [left superior lobe (0.13 × 0.75) + left inferior lobe (0.20 × 0.75) + lingula (0.12 × 0.25) + right superior lobe (0.18 × 0.50) + right inferior lobe (0.25 × 1.0) + right middle lobe (0.12 × 0.50)]. Ant, anterior; LPO, left posterior oblique; Perf, perfusion; post, posterior; PVO, pulmonary vascular obstruction; RPO, right posterior oblique.

Fig. 3

(a) Interobservability PVO measurement. (b) Bland–Altman plot interobservability PVO measurement. PVO, pulmonary vascular obstruction.

Fig. 4

(a) Correlation PVO – 6MWD (min), (b) correlation PVO – log NT-proBNP (pg/ml), (c) correlation PVO – mRAP (mmHg), (d) correlation PVO – mPAP (mmHg), (e) correlation PVO – CO (L/min), (f) correlation PVO – PVR (WU). CO, cardiac output; log NT-proBNP, logarithmic N-terminal probrain natriuretic peptide; mPAP, mean pulmonary arterial pressure; mRAP, mean right atrium pressure; PVO, pulmonary vascular obstruction; PVR, pulmonary vascular resistance; WU, woods units; 6MWD: 6-min walking distance.