Vol 59, No 8 (2003)
Other
Published online: 2005-12-12
The role of exercise ventilation in clinical evaluation and risk stratification in patients with chronic heart failure
DOI: 10.33963/v.kp.82072
Kardiol Pol 2003;59(8):121-126.
Abstract
Background: Patients with chronic heart failure (CHF) are characterised by an increased ventilatory response to exercise. The role of exercise ventilation in the risk stratification and evaluation of patients with CHF has not yet been established.
Aim: To examine the relationship between exercise ventilation indices and clinical parameters of CHF and to assess the prognostic value of the ventilatory response to exercise.
Methods: The study group consisted of 87 patients with CHF (72 males, mean age 58 years) with a mean left ventricular ejection fraction of 32%. Ten patients were in NYHA class I, 38 - in NYHA class II, 34 - in NYHA class III, and 5 - in NYHA class IV. The control group consisted of 20 patients without CHF (13 males, mean age 58 years, mean LVEF - 61%). All studied subjects underwent maximal exercise test with gas-exchange measurement. The following parameters were analysed: peak exercise oxygen consumption [peak VO2 (ml/kg/min)], VE-VCO2 index [a coefficient of linear regression analysis depicting an association between ventilation (VE) and carbon dioxide production (VCO2) during exercise] and VE/VCO2 ratio at peak exercise to VE/VCO2 ratio while at rest (VE/VCO2 peak/rest).
Results: Ventilatory response indices were significantly higher in patients with CHF compared with controls: VE-VCO2 - 37.9±11.1 vs 27.1±4.1; VE-VCO2 peak/rest - 0.89±0.14 vs 0.75±0.10 (p<0.001). In CHF patients a significant positive correlation between ventilatory response parameters and NYHA class (VE-VCO2 - r=0.52; VE/VCO2 peak/rest - r=0.47) and a negative correlation with peak VO2 (VE-VCO2 - r=-0.52; VE/VCO2 peak/rest - r=-0.49) were noted (p<0.0001 for all correlations). No correlation was found between ventilatory parameters and echocardiographic variables or CHF aetiology. During the follow-up period lasting at least 12 months, 17 (22%) patients died. In the univariate Cox model, NYHA class III-IV, decreased peak VO2 and increased VE-VCO2 and VE/VCO2 peak/rest values were significantly associated with the risk of death. The multivariate analysis revealed that VE/VCO2 peak/rest ≥1.0 was the adverse prognostic factor, independent of peak VO2 (p=0.02) and NYHA class (p=0.01). The Kaplan-Meier analysis showed that prognosis during the 18-month follow-up period in patients with enhanced exercise ventilation was worse than in the remaining patients (59% survival in patients with VE/VCO2 peak/rest ≥1.0 59% vs 91% survival in patients with VE/VCO2 peak/rest <1.0, p=0.001).
Conclusions: In patients with stable CHF simple exercise ventilation parameters may provide important clinical and prognostic information.
Aim: To examine the relationship between exercise ventilation indices and clinical parameters of CHF and to assess the prognostic value of the ventilatory response to exercise.
Methods: The study group consisted of 87 patients with CHF (72 males, mean age 58 years) with a mean left ventricular ejection fraction of 32%. Ten patients were in NYHA class I, 38 - in NYHA class II, 34 - in NYHA class III, and 5 - in NYHA class IV. The control group consisted of 20 patients without CHF (13 males, mean age 58 years, mean LVEF - 61%). All studied subjects underwent maximal exercise test with gas-exchange measurement. The following parameters were analysed: peak exercise oxygen consumption [peak VO2 (ml/kg/min)], VE-VCO2 index [a coefficient of linear regression analysis depicting an association between ventilation (VE) and carbon dioxide production (VCO2) during exercise] and VE/VCO2 ratio at peak exercise to VE/VCO2 ratio while at rest (VE/VCO2 peak/rest).
Results: Ventilatory response indices were significantly higher in patients with CHF compared with controls: VE-VCO2 - 37.9±11.1 vs 27.1±4.1; VE-VCO2 peak/rest - 0.89±0.14 vs 0.75±0.10 (p<0.001). In CHF patients a significant positive correlation between ventilatory response parameters and NYHA class (VE-VCO2 - r=0.52; VE/VCO2 peak/rest - r=0.47) and a negative correlation with peak VO2 (VE-VCO2 - r=-0.52; VE/VCO2 peak/rest - r=-0.49) were noted (p<0.0001 for all correlations). No correlation was found between ventilatory parameters and echocardiographic variables or CHF aetiology. During the follow-up period lasting at least 12 months, 17 (22%) patients died. In the univariate Cox model, NYHA class III-IV, decreased peak VO2 and increased VE-VCO2 and VE/VCO2 peak/rest values were significantly associated with the risk of death. The multivariate analysis revealed that VE/VCO2 peak/rest ≥1.0 was the adverse prognostic factor, independent of peak VO2 (p=0.02) and NYHA class (p=0.01). The Kaplan-Meier analysis showed that prognosis during the 18-month follow-up period in patients with enhanced exercise ventilation was worse than in the remaining patients (59% survival in patients with VE/VCO2 peak/rest ≥1.0 59% vs 91% survival in patients with VE/VCO2 peak/rest <1.0, p=0.001).
Conclusions: In patients with stable CHF simple exercise ventilation parameters may provide important clinical and prognostic information.
Keywords: exercise ventilation - chronic heart failure - prognosis
