Background: Six-minute walk test (6MWT) is routinely performed in chronic thromboembolic pulmonary hypertension\n(CTEPH) before pulmonary endarterectomy (PEA). However, the clinical relevance of heart rate response (Ã?â?HR) and\nexercise-induced oxygen desaturation (EID) during 6MWT is remaining unknown.\nMethods: Patients undergoing PEA in our center between 03/2013-04/2014 were assessed prospectively with\nhemodynamic and exercise parameters prior to and 1 year post-PEA. Patients with symptomatic chronic\nthromboembolic disease (mean pulmonary artery pressure (mPAP) <25 mmHg) and clinical relevant obstructive\npulmonary disease were excluded. The following definitions were used: Ã?â?HR = (peak HR - resting HR), percent heart\nrate reserve (HRR) = (peak HR ââ?¬â??rest HR)/(220 - age - rest HR) x 100 and EID=SpO2 ââ?°Â¤88 %.\nResults: Thirty-seven patients (of 116 patients screened) with mPAP of 43.2 Ã?± 8.7 mmHg, pulmonary vascular resistance\n(PVR) of 605.5 Ã?± 228.7 dyn*s/cm5, cardiac index (CI) of 2.4 Ã?± 0.5 l/min/m2 and a 6MWT-distance of 404.7 Ã?± 148.4 m and\na peak VO2 of 12.3 Ã?± 3.4 ml/min/kg prior to PEA were included. Baseline Ã?â?HR during 6MWT was significantly associated\nwith PVR 1 year post-PEA using linear regression analysis (r = 0.43, p = 0.01). Multivariate analysis indicated an\nassociation of HRR during 6MWT and residual PH with a hazard ratio of 1.06 (95 % Confidence interval for\nhazard ratio 0.99ââ?¬â??1.14, p = 0.08). EID was observed commonly during 6MWT but no correlations to outcome\nparameters were found.\nConclusions: This is the first prospective study to describe an association of Ã?â?HR during 6MWT with pulmonary\nhemodynamics 1 year post-PEA. Our preliminary results indicate that HRR derived from 6MWT is of clinical\nsignificance. EID was commonly observed, albeit failed as a significant prognostic factor.
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