OBJECTIVE To see whether degree of pulmonary hypertension or severity of cardiac failure affect the success of pulmonary thromboendarterectomy (PTE) in chronic thromboembolic pulmonary hypertension. METHODS From May 1996 to June 1999, 33 patients, all in New York Heart Association (NYHA) class 3 or 4 were treated with PTE. Preoperative hemodynamic values were: central venous pressure (CVP) 8+/-6 (1-23), mean pulmonary artery pressure (mPAP) 50+/-10 (30-69), cardiac output (CO) 3.3+/-0.9 (1.8-5.2), pulmonary vascular resistance (PVR) 1056+/-344 (523-1659), and right ventricle ejection fraction (RVEF) 12+/-5 (5-21). To establish whether some hemodynamic or cardiac variables correlate with surgical failure (early death or functional non-success), these patients were divided into a low risk or a high risk group for each variable: CVP (<9 or > or =9), mPAP (<50 or > or =50), CO (> or =3.5 or <3.5), PVR (> or =1100 or <1100), and RVEF (> or = 10 or <10). The duration of 3-4 NYHA class period (<24 or > or = 24 months) was also included in the study. RESULTS Three patients (9. 1%) died in hospital, one (3.0%) underwent lung transplant shortly after PTE, and in five cases (15.2%) mPAP and PVR at the 3-month follow-up examination corresponded with our definition of functional nonsuccess (mPAP and PVR decreased by less than 40% of preoperative values). One of the five functional nonsuccess patients underwent lung transplant 3 months after the operation and another died 17 months after the operation from a non-related cause. Thus PTE was successful in 24 patients and unsuccessful in nine. None of the hemodynamic variables considered was found to be associated with the disparate outcomes. At the 3-month examination, all surviving patients were in NYHA class 1 or 2 except for three in NYHA class 3. At 2 years, hemodynamic values were: CVP 2+/-2 (0-4), mPAP 16+/-3 (12-21), CO 5.0+/-1.0 (3.4-6.5), PVR 182+/-51 (112-282), and RVEF 35+/-5 (26-40). All differences were significant with respect to baseline values (P<0.001). Preoperative mPAP and RVEF values had a strict linear correlation (R=0.45; P=0.014). CONCLUSIONS None of the variables considered was correlated with early death or functional nonsuccess. Neither preoperative severity of pulmonary hypertension nor degree of cardiac failure influenced the outcome of the operation. PTE leads to hemodynamic recovery even in very compromised patients.