Journal of Cardiac and Pulmonary Rehabilitation
Open Access

Cardiopulmonary exercise testing; Surgical risk assessment; Heart failure; Peak vo₂; Ventilatory efficiency; Prognostic markers; Preoperative evaluation; Functional capacity; Risk stratification; Cardiac surgery outcomes

Introduction

Heart failure (HF) remains a global health challenge, characterized by impaired cardiac output, reduced exercise tolerance, and significant morbidity and mortality. For patients with advanced HF, surgical interventions such as heart transplantation, left ventricular assist device (LVAD) implantation, or valvular surgery may be indicated to improve survival and quality of life [1-5]. However, the perioperative risk associated with these procedures is considerable, necessitating precise risk stratification tools. Cardiopulmonary exercise testing (CPET) has emerged as a valuable, non-invasive modality for evaluating functional capacity and cardiovascular reserve in this context. CPET integrates respiratory gas exchange with hemodynamic response to exertion, yielding objective parameters such as peak oxygen consumption (peak VO₂), ventilatory efficiency (VE/VCO₂ slope), and oxygen pulse—each offering prognostic insight. This study investigates the predictive value of key CPET parameters in assessing surgical risk among heart failure patients. The objective is to determine which CPET-derived metrics most accurately correlate with post-surgical outcomes, including mortality, length of hospital stay, and incidence of complications, thereby informing perioperative decision-making and individualized care planning [6-10].

Discussion

The analysis of CPET parameters in the context of surgical risk prediction for heart failure patients yielded several significant findings. Among the tested metrics, peak VO₂ emerged as the strongest single predictor of both early postoperative mortality and prolonged intensive care unit (ICU) stay. Patients with peak VO₂ values below 10 mL/kg/min demonstrated significantly higher risk for adverse surgical outcomes, supporting existing guideline thresholds for transplant eligibility and advanced heart failure therapies. The VE/VCO₂ slope also showed strong prognostic value, with steeper slopes (>35) correlating with increased likelihood of ventilatory inefficiency and poor perioperative tolerance. Additionally, a reduced oxygen pulse, representing diminished stroke volume response to exercise, was associated with higher postoperative complication rates, including arrhythmias and low cardiac output syndrome. Multivariate regression confirmed that these three variables independently predicted surgical risk after adjusting for age, ejection fraction, and comorbidities. Interestingly, the predictive power of CPET extended beyond mortality to other clinical endpoints, such as prolonged mechanical ventilation, hospital readmission within 30 days, and delayed functional recovery. Patients classified as high risk based on CPET results also exhibited longer rehabilitation timelines and slower return to baseline activity levels. These findings highlight the utility of CPET not only in preoperative clearance but also in forecasting postoperative resource needs and planning targeted interventions. Moreover, CPET may assist clinicians in identifying patients who could benefit from prehabilitation strategies to enhance fitness and improve surgical candidacy. Despite its strengths, the study also acknowledged limitations, including variability in CPET protocols across centers and the influence of beta-blocker therapy on test results. The need for standardized testing conditions and clinician training in CPET interpretation remains crucial. Nevertheless, as a functional and integrative assessment tool, CPET provides a physiological dimension that complements traditional imaging and biomarker-based evaluations, offering a comprehensive approach to risk stratification in surgical heart failure patients.

Conclusion

Cardiopulmonary exercise testing offers robust predictive value in assessing surgical risk among heart failure patients. Parameters suchs as peak VO₂, VE/VCO₂ slope, and oxygen pulse provide critical insights into cardiopulmonary reserve and correlate strongly with surgical outcomes, including mortality and postoperative complications. Incorporating CPET into routine preoperative evaluation enables more accurate risk stratification, enhances patient selection for advanced therapies, and facilitates proactive perioperative planning. Given the complexity of managing heart failure patients undergoing cardiac surgery, CPET serves as a powerful tool for guiding clinical decisions, improving safety, and optimizing long-term recovery. Future research should focus on refining CPET cut-off thresholds, exploring integration with machine learning models for dynamic risk prediction, and evaluating its role in personalized surgical pathways for this high-risk population.