title: VE/VCO2 slope is associated with abnormal resting haemodynamics and is a predictor of long-term survival in chronic heart failure.
abstract: BACKGROUND
  Patients with chronic heart failure (CHF) present with exercise-induced hyperpnea, but its pathophysiological mechanism has not been thoroughly investigated. We aimed to determine the relationship between exercise-induced hyperpnea, resting haemodynamic measurements and the validity of ventilatory response (V(E)/V(CO(2)) slope) as a mortality predictor in CHF patients.
  
  
  METHODS
  Ninety-eight CHF patients (90M/8F) underwent a symptom-limited treadmill cardiopulmonary exercise test (CPET). Right heart catheterization and radionuclide ventriculography were performed within 72 h of CPET.
  
  
  RESULTS
  Twenty-seven patients died from cardiac causes during 20+/-6 months follow-up. Non-survivors had a lower peak oxygen consumption (V(O(2)p)), (16.5+/-4.9 vs. 20.2+/-6.1, ml/kg/min, p=0.003), a steeper V(E)/V(CO(2)) slope (34.8+/-8.3 vs. 28.9+/-4.8, p<0.001) and a higher pulmonary capillary wedge pressure (PCWP) (19.5+/-8.6 vs. 11.7+/-6.5 mm Hg, p=0.008) than survivors. By multivariate survival analysis, the V(E)/V(CO(2)) slope as a continuous variable was an independent prognostic factor (chi(2): 8.5, relative risk: 1.1, 95% CI: 1.03-1.18, p=0.004). Overall mortality was 52% in patients with V(E)/V(CO(2)) slope > or =34 and 18% in those with V(E)/V(CO(2)) slope <34 (log rank: 18.5, p<0.001). In a subgroup of patients (V(O(2)p): 10-18 ml/kg/min), V(E)/V(CO(2)) slope was a significant predictor of mortality (relative risk: 6.2, 95% CI: 1.7-22.2, p=0.002). Patients with high V(E)/V(CO(2)) slope had higher resting PCWP (19.9+/-9.1 vs. 11.3+/-5.7 mmHg, p<0.001) and V(E)/V(CO(2)) slope correlated significantly with PCWP (r: 0.57, p<0.001).
  
  
  CONCLUSIONS
  The V(E)/V(CO(2)) slope, as an index of ventilatory response to exercise, improves the risk stratification of CHF patients. Interstitial pulmonary oedema may be a pathophysiological mechanism of inefficient ventilation during exercise in these patients.
authors.affiliation: Pulmonary and Critical Care Medicine Department, Cardiopulmonary Exercise Testing And Rehabilitation Laboratory, Evgenidio Hospital, National and Kapodestrian University of Athens, Greece. snanas@cc.uoa.gr
authors.forename: Serafim N
authors.initials: SN
authors.lastname: Nanas
authors.forename: John N
authors.initials: JN
authors.lastname: Nanas
authors.forename: Dimitrios Ch
authors.initials: DCh
authors.lastname: Sakellariou
authors.forename: Stavros K
authors.initials: SK
authors.lastname: Dimopoulos
authors.forename: Stavros G
authors.initials: SG
authors.lastname: Drakos
authors.forename: Smaragdo G
authors.initials: SG
authors.lastname: Kapsimalakou
authors.forename: Christina A
authors.initials: CA
authors.lastname: Mpatziou
authors.forename: Ourania G
authors.initials: OG
authors.lastname: Papazachou
authors.forename: Anargyros S
authors.initials: AS
authors.lastname: Dalianis
authors.forename: Maria I
authors.initials: MI
authors.lastname: Anastasiou-Nana
authors.forename: Charis
authors.initials: C
authors.lastname: Roussos
mesh_terms: D000328:Adult; D002245:Carbon Dioxide / Q000032:analysis*; D002303:Cardiac Output, Low / Q000503:physiopathology*; D005080:Exercise Test; D005260:Female; D006439:Hemodynamics; D006801:Humans; D008297:Male; D008875:Middle Aged; D010101:Oxygen Consumption; D011379:Prognosis; D016019:Survival Analysis
chemical_list: D002245:Carbon Dioxide