Peak VO2 and VE/VCO2 exhibit differential prognostic capacity for predicting cardiac events

Abstract

Abstract Background Cardiopulmonary exercise testing (CPET) are commonly used to assess the functional capacity of patients with heart failure. While both peak oxygen uptake (VO2) and ventilatory efficiency (VE/CO2) are significant prognostic factors in heart failure, their values may not always be concordant. Methods This retrospective study included 688 patients who underwent both CPET and supine bicycle echocardiography (SBE) simultaneously. The primary endpoint of the study was defined as heart failure hospitalization or cardiac death. The patients were categorized into subgroups based on their VO2 and VE/VCO2 slope values. Results After median follow-up of 89 months, 111 (16.4%) patients developed cardiac events. The mean age and ejection fraction were 58 years and 59%. In multivariate analysis, both VO2 and VE/VCO2 remained powerful predictors of cardiac events after adjusting for age, ejection fraction, baseline or exercise E/e’, and peak TR velocity. Subgroup analysis revealed that Group III (VO2 >20 and VE/VCO2 >30) and IV (VO2 <20 and VE/VCO2 >30) had a significantly higher risk of cardiac events, with hazard ratios of 3.38 (CI 1.36-8.40) and 8.40 (CI 3.86-18.34), respectively, compared to Group I (VO2 >20 and VE/VCO2 <30). Group II (VO2 <20 and VE/VCO2 <30) had a non-significantly increased risk of cardiac events with a hazard ratio of 2.04 (CI 0.80-5.21) compared to Group I (Fig). Conclusion Both VO2 and VE/VCO2 slope were found to be excellent predictors of cardiac events in patients who underwent CPET and SBE. However, there is a slight difference between the two parameters, and poorer ventilatory inefficiency was found to be more associated with a worsened prognosis. The study suggests that the risk stratification using the VE/VCO2 slope and peak VO2 values can provide valuable information for clinicians in managing patients with heart failure.