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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 CO2 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 O2p), (16.5±4.9 vs. 20.2±6.1, ml/kg/min, p =0.003), a steeper V E/V CO2 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 CO2 slope as a continuous variable was an independent prognostic factor (χ 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 CO2 slope ≥34 and 18% in those with V E/V CO2 slope <34 (log rank: 18.5, p <0.001). In a subgroup of patients (V O2p: 10–18 ml/kg/min), V E/V CO2 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 CO2 slope had higher resting PCWP (19.9±9.1 vs. 11.3±5.7 mmHg, p <0.001) and V E/V CO2 slope correlated significantly with PCWP (r: 0.57, p <0.001). Conclusions: The V E/V CO2 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. [Copyright &y& Elsevier]

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.