Background <p>Few non-invasive approaches are available for improving coronary function in intermediate-risk chronic coronary syndrome (CCS) patients. Over the past 30&#xa0;years, enhanced external counterpulsation (EECP) has been widely accepted and recommended for treating CCS in clinical guidelines. However, the effect of EECP on coronary function remains to be quantitatively validated in intermediate-risk CCS patients. Fractional flow reserve (FFR) is a gold standard (quantitative index) of coronary artery function, and FFR &lt; 0.80 is regarded as an indicator for percutaneous coronary intervention (PCI) in clinical decision-making. However, FFR is invasive and cannot be performed repeatedly within a short time interval; therefore, FFR is not suitable for large-scale verification of the effect before and after EECP treatment. Conversely, with advancements in numerical theory and computation hardware, FFR derived from coronary computed tomography angiography (FFR_CT) performs similarly to FFR used in coronary artery function measurement. Additionally, FFR_CT is non-invasive and highly acceptable to patients. Therefore, in this study, we aim to explore whether EECP therapy can improve FFR_CT in patients with intermediate-risk CCS and further enhance the long-term prognosis of CCS.</p> Methods <p>This prospective, multicentre, randomised controlled trial is blinded to the examination executors and analysts. One hundred four participants will be recruited, and they will be divided into the EECP and control groups. The primary outcome of this study is the between-group difference in FFR_CT changes from baseline to follow-up. The secondary outcomes refer to between-group differences in ΔFFR_CT, wall shear stress, axial plaque stress, total exercise time, time to 1 mm ST-segment depression, Seattle Angina Questionnaire score, and cardiovascular-related composite endpoint events.</p> Discussion <p>This is the first study to use the non-invasive coronary artery function index, FFR_CT, to evaluate the efficacy of EECP in patients with CCS. It comprehensively evaluates the treatment efficacy from multiple dimensions, including exercise capacity, symptom changes, and prognosis. Therefore, this will potentially provide reliable evidence to inform treatment strategies for CCS.</p> Trial registration <p>Trial registration number: ChiCTR2400079915. Registered on January 16, 2024 (retrospectively registered), <a href="https://www.chictr.org.cn/about.html">https://www.chictr.org.cn/about.html</a>.</p>