Early Postoperative Pulmonary Vascular Compliance Predicts Outcome After Pulmonary Endarterectomy for Chronic Thromboembolic Pulmonary Hypertension

BACKGROUND: Despite a major reduction in pulmonary vascular resistance (PVR), patients with chronic thromboembolic pulmonary hypertension (CTEPH) do not always return to functional New York Heart Association (NYHA) class I after pulmonary endarterectomy (PEA). We hypothesized that residual abnormal compliance (Cp) after PEA is associated with incomplete functional recovery despite major improvement in PVR. METHODS: The Cp of 34 consecutive patients with CTEPH was assessed before and after PEA. Cp was defined as stroke volume over pulse pressure and was divided into three groups: < 2.0 mL/mm Hg, 2.0 to 3.9 mL/mm Hg, and ≥ 4 mL/mm Hg. To establish predicted Cp after PEA, we collected an age- and gender-matched control group. RESULTS: Before PEA, Cp was < 2.0 mL/mm Hg in 82% (n = 28) of the patients. After PEA, Cp improved to 2.0 to 3.9 mL/mm Hg in 11 patients and to ≥ 4.0 mL/mm Hg in 14 patients. Residual Cp < 2.0 mL/mm Hg was associated with delayed extubation and prolonged hospital stay. At 3 months' follow-up, 13 patients (93%) with postoperative Cp ≥ 4.0 mL/mm Hg returned to NYHA class I, whereas 45% with Cp of 2.0 to 3.9 mL/mm Hg and 25% with Cp < 2.0 mL/mm Hg returned to NYHA class I. In multivariate analysis, postoperative Cp ≥ 4.0 mL/mm Hg was the only predictor of functional recovery to NYHA class I. The group of patients with postoperative Cp ≥ 4.0 mL/mm Hg was also the only group to achieve hemodynamic parameters similar to those of their matched control subjects. CONCLUSIONS: Postoperative Cp is an important predictor of recovery after PEA. Residual vascular stiffness after PEA can be associated with persistent functional limitation and lack of complete remodeling of the right ventricle.