title: Heart rate response during 6-minute walking testing predicts outcome in operable chronic thromboembolic pulmonary hypertension.
abstract: Six-minute walk test (6MWT) is routinely performed in chronic thromboembolic pulmonary hypertension (CTEPH) before pulmonary endarterectomy (PEA). However, the clinical relevance of heart rate response (ΔHR) and exercise-induced oxygen desaturation (EID) during 6MWT is remaining unknown.
  
  
  
  Patients undergoing PEA in our center between 03/2013-04/2014 were assessed prospectively with hemodynamic and exercise parameters prior to and 1 year post-PEA. Patients with symptomatic chronic thromboembolic disease (mean pulmonary artery pressure (mPAP) <25 mmHg) and clinical relevant obstructive pulmonary disease were excluded. The following definitions were used: ΔHR = (peak HR - resting HR), percent heart rate reserve (HRR) = (peak HR -rest HR)/(220 - age - rest HR) x 100 and EID = SpO2 ≤88 %.
  
  
  
  Thirty-seven patients (of 116 patients screened) with mPAP of 43.2 ± 8.7 mmHg, pulmonary vascular resistance (PVR) of 605.5 ± 228.7 dyn*s/cm(5), cardiac index (CI) of 2.4 ± 0.5 l/min/m(2) and a 6MWT-distance of 404.7 ± 148.4 m and a peak VO2 of 12.3 ± 3.4 ml/min/kg prior to PEA were included. Baseline ΔHR during 6MWT was significantly associated with PVR 1 year post-PEA using linear regression analysis (r = 0.43, p = 0.01). Multivariate analysis indicated an association of HRR during 6MWT and residual PH with a hazard ratio of 1.06 (95 % Confidence interval for hazard ratio 0.99-1.14, p = 0.08). EID was observed commonly during 6MWT but no correlations to outcome parameters were found.
  
  
  
  This is the first prospective study to describe an association of ΔHR during 6MWT with pulmonary hemodynamics 1 year post-PEA. Our preliminary results indicate that HRR derived from 6MWT is of clinical significance. EID was commonly observed, albeit failed as a significant prognostic factor.
authors.affiliation: Department of Pneumology, Kerckhoff Heart, Rheuma and Thoracic Center, Bad Nauheim, Germany. manuel.richter@innere.med.uni-giessen.de.|Department of Internal Medicine, Justus-Liebig-University Giessen, Universities of Giessen and Marburg Lung Center (UGMLC), Member of the German Center for Lung Research (DZL), Giessen, Germany. manuel.richter@innere.med.uni-giessen.de.
authors.forename: Manuel Jonas
authors.initials: MJ
authors.lastname: Richter
authors.affiliation: Department of Internal Medicine, Justus-Liebig-University Giessen, Universities of Giessen and Marburg Lung Center (UGMLC), Member of the German Center for Lung Research (DZL), Giessen, Germany.|Department of Internal Medicine V, University of Munich, Comprehensive Pneumology Center, member of the German Center for Lung Research (DZL), Munich, Germany.
authors.forename: Katrin
authors.initials: K
authors.lastname: Milger
authors.affiliation: Department of Internal Medicine, Justus-Liebig-University Giessen, Universities of Giessen and Marburg Lung Center (UGMLC), Member of the German Center for Lung Research (DZL), Giessen, Germany.
authors.forename: Khodr
authors.initials: K
authors.lastname: Tello
authors.affiliation: Department of Internal Medicine, Justus-Liebig-University Giessen, Universities of Giessen and Marburg Lung Center (UGMLC), Member of the German Center for Lung Research (DZL), Giessen, Germany.
authors.forename: Philipp
authors.initials: P
authors.lastname: Stille
authors.affiliation: Department of Internal Medicine, Justus-Liebig-University Giessen, Universities of Giessen and Marburg Lung Center (UGMLC), Member of the German Center for Lung Research (DZL), Giessen, Germany.
authors.forename: Werner
authors.initials: W
authors.lastname: Seeger
authors.affiliation: Department of Thoracic Surgery, Kerckhoff Heart, Rheuma and Thoracic Center, Bad Nauheim, Germany.
authors.forename: Eckhard
authors.initials: E
authors.lastname: Mayer
authors.affiliation: Department of Pneumology, Kerckhoff Heart, Rheuma and Thoracic Center, Bad Nauheim, Germany.|Department of Internal Medicine, Justus-Liebig-University Giessen, Universities of Giessen and Marburg Lung Center (UGMLC), Member of the German Center for Lung Research (DZL), Giessen, Germany.|Department of Medicine, Imperial College London, London, UK.
authors.forename: Hossein A
authors.initials: HA
authors.lastname: Ghofrani
authors.affiliation: Department of Internal Medicine, Justus-Liebig-University Giessen, Universities of Giessen and Marburg Lung Center (UGMLC), Member of the German Center for Lung Research (DZL), Giessen, Germany.
authors.forename: Henning
authors.initials: H
authors.lastname: Gall
mesh_terms: D000368:Aged; D062186:Arterial Pressure; D002908:Chronic Disease; D004452:Echocardiography; D004691:Endarterectomy; D005260:Female; D005858:Germany; D006339:Heart Rate; D006801:Humans; D006976:Hypertension, Pulmonary / Q000503:physiopathology*; D016014:Linear Models; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D010101:Oxygen Consumption; D011446:Prospective Studies; D011651:Pulmonary Artery / Q000503:physiopathology; D013923:Thromboembolism / Q000150:complications* / Q000601:surgery; D014655:Vascular Resistance; D000070857:Walk Test
keywords: Chronic thromboembolic pulmonary hypertension; Heart rate response; Oxygen desaturation; Pulmonary endarterectomy