Aims: Decreased total compliance of the pulmonary vascular bed is associated with increased mortality in patients with pulmonary arterial hypertension (PAH). We investigated whether proximal pulmonary artery stiffness, in terms of area distensibility and noninvasively assessed relative area change (RAC), calculated as relative cross-sectional area change, predicts mortality in patients with PAH.
Methods and results: Eighty-six subjects underwent right-heart catheterization and MRI to assess area distensibility and RAC. Patients were followed up to 48 months. Kaplan-Meier plot and Cox proportional hazards regression analyses assessed the predictive value of area distensibility and RAC. In 70 patients, the diagnosis PAH was confirmed, and 16 subjects served as control subjects. In comparison with control subjects, proximal pulmonary arteries of patients were distended (685 ± 214 mm2 vs 411 ± 153 mm2, p < 0.001), less distensible (area distensibility = 0.46 ± 0.38·10−2 mm Hg−1 vs 3.69 ± 1.96·10−2 mm Hg−1, p < 0.0001), and RAC was smaller (20 ± 10% vs 58 ± 21%, p < 0.0001) [mean ± SD]. RAC showed an inverse curvilinear relation with mean pulmonary artery pressure (R2 = 0.47). Eighteen patients (26%) died because of cardiopulmonary causes. Patients with a pulmonary artery RAC ≤ 16% had a worse prognosis than those with a value > 16% (log-rank p < 0.001). RAC predicted mortality better than area distensibility.
Conclusion: Noninvasively measured pulmonary artery RAC predicts mortality in patients with PAH.