Clinical Utility of the Cardiorespiratory Optimal Point in Patients with Heart Failure

KROESEN, S. H., E. A. BAKKER, J. A. SNOEK, R. R. J. VAN KIMMENADE, J. MOLINGER, C. G. ARAUJO, M. T. E. HOPMAN, and T. M. H. EIJSVOGELS. Clinical Utility of the Cardiorespiratory Optimal Point in Patients with Heart Failure. Med. Sci. Sports Exerc., Vol. 55, No. 10, pp. 1727-1734, 2023. Introduction: We assessed the cardiorespiratory optimal point (COP)-the minimal. V E/V. O2 in a given minute of an incremental cardiopulmonary exercise test-in patients with heart failure (HF) and aimed to determine 1) its association with patient and disease characteristics, 2) changes after an exercise-based cardiac rehabilitation program (CR), and 3) the association with clinical outcomes. Methods: We studied 277 HF patients (67 (58-74) yr, 30% female, 72% HF with restricted ejection fraction) between 2009 and 2018. Patients participated in a 12- to 24-wk CR program, and COP was assessed pre- and post-CR. Patient and disease characteristics and clinical outcomes (mortality and cardiovascular-related hospitalization) were extracted from patient files. The incidence of clinical outcomes was compared across COP tertiles (low, <26.0; moderate, 26.0-30.7; high, >30.7). Results: Median COP was 28.2 (24.9-32.1) and was reached at 51%+/- 15% of V. O2peak. Lower age, female sex, higher body mass index, the absence of a pacemaker or the absence of chronic obstructive pulmonary disease, and lower N-terminal prohormone brain natriuretic peptide concentrations were associated with a lower COP. Participation in CR reduced COP (-0.8; 95% confidence interval, -1.3 to -0.3). Low COP had a reduced risk (adjusted hazard ratio, 0.53; 95% confidence interval, 0.33-0.84) for adverse clinical outcomes as compared with high COP. Conclusions: Classic cardiovascular risk factors are associated with a higher, more unfavorable, COP. CR-based exercise training reduces COP, whereas a lower COP is associated with a better clinical prognosis. As COP can be established during a submaximal exercise test, this may offer novel risk stratification possibilities for HF care programs.