Chronic thromboembolic pulmonary hypertension (CTEPH) is predominantly a disease of the elastic pulmonary arteries. However, the impact of CTEPH and the results of pulmonary endarterectomy (PEA) on the pulmonary arterial compliance (Cp) have not been analyzed systematically.
We assessed Cp in 41 consecutive patients (23 females, age 57 ± 13 years) evaluated for CTEPH in our institution. CTEPH was confirmed by pulmonary angiogram in all patients. A total of 27 patients underwent PEA (68%). Cp was defined by stroke volume over pulse pressure (SV/PP), and SV was calculated by cardiac output (CO) divided by heart rate. Normal Cp is between 5 and 10 mL/kg at rest. PH was defined by mPAP > 25 mmHg at rest.
Cp ranged between 0.5 and 3.8 (median 1.1) mL/mmHg. There was an inverse relationship between Cp and pulmonary vascular resistance (p < 0.0001). Cp was abnormal in 5 patients with CTEPH (1.9 to 3.4, median 2.2 mL/mmHg) despite the absence of PH at rest, 2 of these patients underwent PEA with normalization of Cp. Among 27 patients undergoing PEA, 1 died postoperatively for an in-hospital operative mortality of 3.7%. Cp improved from 1.4 ± 0.9 before surgery to 2.4 ± 1.3 mL/mmHg immediately after PEA and to 3.2 ± 1.6 mL/mmHg on the second postoperative day (p < 0.0001). After a median follow-up of 18 months (range 1–45 months), NYHA class improved from 3.2 ± 0.6 to 1.4 ± 0.5, and all but one patient have remained in NYHA class I (62%) or II (38%) during follow-up without pulmonary vasodilatative agents. All patients with postoperative Cp > 4 mL/mmHg were in NYHA class I. The 6` walk distance improved from 344 ± 144m preoperatively to 456 ± 97m after PEA (p = 0.02). There was a significant correlation between the change in Cp and improvement in 6’walk distance between the pre- and post-operative measurements (p = 0.006).
Cp can be abnormal in patients with CTEPH despite the absence of PH at rest and major improvement in Cp is observed after PEA.
Cp appears to be an important, early marker to assess patients with CTEPH.
Marc De Perrot, No Financial Disclosure Information; No Product/Research Disclosure Information