Value of lung perfusion scintigraphy in patients with idiopathic pulmonary arterial hypertension: a patchy pattern to consider

The ventilation/perfusion lung scan is recommended to exclude chronic thromboembolic pulmonary hypertension in the diagnostic algorithm of pulmonary hypertension, but its role in pulmonary arterial hypertension (PAH) has not been well explored. We characterized the lung perfusion pattern assessed by lung perfusion scintigraphy in idiopathic PAH (IPAH) patients and evaluate the potential prognostic significance of the patchy pattern perfusion defect. A total of 318 patients with IPAH confirmed by right heart catheterization who performed lung perfusion scintigraphy were included. On lung perfusion scintigraphy, 134 patients had normal lung perfusion and 184 patients showed patchy perfusion defects. In comparison to patients with normal lung perfusion, patients with patchy perfusion defects experienced significantly higher mean pulmonary arterial pressure (58.0 ± 15.4 mmHg vs. 54.1 ± 16.2 mmHg, P = 0.027) and total pulmonary resistance (1192.6 ± 533.7 dyn·s·cm(−5) vs. 1067.2 ± 549.3 dyn·s·cm(−5), P = 0.042). During a median follow-up period of 884.0 days, 53 patients reached the primary endpoint of all-cause mortality. On univariate Cox analysis, the patchy pattern of perfusion defect was significantly associated with the all-cause mortality (hazard ratio [HR] = 2.47, 95% confidence interval [CI] = 1.32–4.63, P = 0.005). Patients with patchy perfusion defects had a worse outcome (log-rank = 8.605, P = 0.003). On multivariate analysis, the patchy pattern remained as a significant independent predictor of the endpoint (HR = 2.30, 95% CI = 1.22–4.31, P = 0.010). IPAH patients presented with heterogeneity in lung perfusion and the patchy pattern of lung perfusion defect commonly existed. Patients with patchy pattern identified by lung perfusion scintigraphy were associated with more severe disease and worse outcome.