Circulatory reserve determines recovery potential during inpatient cardiac rehabilitation
T Sugimoto, S Yamashita, T Adachi, M Kato, Y SeoAbstract
Background
Achieving functional independence is a central goal of inpatient cardiac rehabilitation. While the Barthel Index (BI) reflects a patient’s current functional status, it may not capture recovery potential. The role of circulatory reserve assessed by exercise stress echocardiography in predicting rehabilitation outcomes remains unclear.
Purpose
To determine whether exercise-derived circulatory reserve improves prediction of functional independence at discharge beyond baseline functional status.
Methods
Fifty-three consecutive patients with cardiovascular comorbidities were enrolled from a Japanese convalescent rehabilitation ward and underwent exercise stress echocardiography at the initiation of inpatient cardiac rehabilitation. The median baseline BI was 55 (IQR 40–70), and the median hospital stay was 66 days. Functional independence at discharge was defined as BI ≥85. The ESE-ADL Score (0–3 points) was derived from peak work rate ≥20 W, peak cardiac power output ≥1.1 W, and resting SpO₂ ≥97%. The ESE-ADL Plus Score (0–4 points) additionally incorporated baseline BI ≥65. Model performance was evaluated using discrimination (AUC), calibration (Brier score), reclassification (integrated discrimination improvement [IDI], continuous net reclassification improvement [NRI]), and decision curve analysis.
Results
Patients achieving functional independence demonstrated significantly greater exercise-derived circulatory reserve, including higher peak cardiac power output, stroke volume, work rate, and resting SpO₂, despite similar resting left ventricular ejection fraction. The ESE-ADL Score improved discrimination compared with baseline BI alone (AUC 0.841 vs 0.808), while the ESE-ADL Plus Score further enhanced predictive performance (AUC 0.886) and demonstrated superior reclassification and net benefit across clinically relevant threshold probabilities. These findings suggest that circulatory reserve provides incremental prognostic information beyond baseline functional assessment.
Conclusions
Baseline BI reflects current functional status, whereas exercise-derived circulatory reserve reflects recovery potential. Integration of both domains improves prediction of functional independence and may support individualized intensity and resource allocation strategies in cardiac rehabilitation.Table 1Table 2