Comparison of Cardiopulmonary Exercise Test Variables to Predict Adverse Events in Patients with Heart Failure.

Purpose: Given the rising burden of heart failure (HF), stratification of patients at increased risk for adverse events is critical. We aimed to compare the predictive value of various maximal and submaximal cardiopulmonary exercise test (CPET) variables for adverse events in patients with HF.

Methods: A total of 237 patients with HF (66 (58-73) yr, 30% women, 70% HF with reduced ejection fraction) completed a CPET and had 5 yr of follow-up. Baseline characteristics and clinical outcomes (all-cause mortality, major adverse cardiovascular events, and cardiovascular-related hospitalization) were extracted from electronic patient files. Receiver operating characteristics curves for maximal (e.g., peak V̇O 2 ) and submaximal CPET variables (e.g., VE/V̇CO 2 slope, cardiorespiratory optimal point (COP), V̇O 2 at anaerobic threshold) were compared using the Akaike Information Criterion (AIC) method, whereas their calibration was assessed.

Results: One hundred three participants (43%) reached the composite endpoint, and 55 (23%) died. Percent predicted peak V̇O 2 was the best predictor for adverse outcomes (AIC: 302.6) followed by COP (AIC: 304.3) and relative peak V̇O 2 (mL·(kg·min) -1 , AIC: 304.4). Relative peak V̇O 2 (AIC: 217.1) and COP (AIC: 224.4) were also among the three best predictors for mortality, together with absolute peak V̇O 2 (mL·min -1 , AIC: 220.5). A good calibration between observed and predicted event rate was observed for these variables.

Conclusions: Percent predicated and relative peak V̇O 2 had the best predictive accuracy for adverse events and mortality, but the submaximal COP had a noninferior predictive accuracy for adverse events in patients with HF. These findings highlight the potential of submaximal exercise testing in patients with HF.