TITLE:
Cardiopulmonary Exercise and Respiratory Function Testing and Their Association with Mortality and Heart Transplantation in Patients with Heart Failure
AUTHORS:
Alam Merchant, Jason Li, Michael Fong, Ahmet Baydur
KEYWORDS:
Cardiopulmonary Exercise Testing, Heart Failure, Heart Transplantation, Oxygen Pulse, Oxygen Uptake Efficiency Slope, Ventilatory Equivalents
JOURNAL NAME:
Open Journal of Respiratory Diseases,
Vol.15 No.4,
September
28,
2025
ABSTRACT: Background: Among cardiopulmonary exercise testing (CPET) variables, maximum oxygen uptake (VO2max) and ventilatory efficiency (VE/VCO2 slope) are frequently used predictive indices for mortality and heart transplantation in patients with advanced heart failure. Objective: To identify less commonly used variables associated with mortality and eventual transplantation for heart failure patients and assess their reliability. Methods: Patients identified with stable advanced heart failure underwent symptom-limited CPET using the Godfrey protocol. We compared variables between eventually transplanted and non-transplanted, and, separately, between living and deceased patients. Derived variables included Ve/VCO2, Ve/VCO2/O2, chronotropic index (CI), and oxygen uptake efficiency slope (OUES). Results: One hundred sixty-six individuals (52 ± 15.6 y) were identified with heart failure. Left ventricular ejection fraction (LVEF) was 38 ± 17%. Eighteen (11%) patients subsequently underwent transplantation. Two (12%) transplanted and 26 (18%) non-transplanted patients expired during the study. Expired patients exhibited significantly lower VO2peak, VO2 at AT, VCO2peak, and O2/pulse, and higher peak Ve/VCO2, Ve/VCO2/O2, Ve/VCO2 slope, and Ve/VCO2/VO2 than living patients. Oxygen uptake efficiency slope (OUES) was lower in the deceased group (p 2 was 7.7% less in expired patients (p = 0.01). VO2peak was 28% lower in patients who subsequently underwent transplantation. These individuals also exhibited significantly lower OUES and peak PetCO2, and 94% higher CI than the non-transplanted group. Conclusions: Our findings confirm the potential utility of less commonly used indices of CPET, such as Ve/VCO2/O2, OUES, and CI, in strengthening the identification of suitable candidates for heart transplantation in the context of heart failure management.