Extent and predictors of guideline-directed medical therapy optimization during cardiac rehabilitation in patients with heart failure.

Background: Cardiac rehabilitation (CR) may offer a structured framework for guideline-directed medical therapy (GDMT) optimization, but its real-world impact is uncertain. We aimed to quantify GDMT optimization and identify its clinical predictors during CR. Methods: This retrospective single-centre study included patients hospitalized for acute HF with reduced (HFrEF) or mildly reduced (HFmrEF) ejection fraction who subsequently underwent first inpatient or ambulatory CR at Nancy University Hospital (2021-2024). Changes in GDMT optimization were evaluated using the HF prescription and the KCMO scores and expressed as adjusted standardized differences (ASD). Multivariable linear regression identified independent predictors of optimization. Results: Among the 106 patients included (84 % HFrEF, mean age 59 years; 75 % male), baseline GDMT use was high, but doses were suboptimal. During CR, significant uptitration occurred across all major drug classes, including angiotensin receptor-neprilysin inhibitors (ASD: +22 %), beta-blockers (ASD: +21 %), mineralocorticoid receptor antagonists (ASD: +43 %), and sodium-glucose cotransporter 2 inhibitors (ASD: +45 %) (all p < 0.001). Overall GDMT optimization improved significantly, as evidenced by increases in both the KCMO (ASD: +39.9) and HF prescription (ASD: +1.27) scores (both p < 0.001), with consistent effects across inpatient and ambulatory settings. In multivariable analysis, higher loop-diuretic dose and prior treatment by HF specialists were associated with less optimization, whereas hypertension predicted greater intensification. Conclusions: Cardiac rehabilitation after HF hospitalization promoted substantial GDMT optimization, especially in hypertensive patients. Higher loop-diuretic dose at admission predicted less optimization, suggesting that minimizing diuretic doses may ease GDMT titration.