EECP intervention and coronary flow reserve in chronic coronary syndrome: a protocol of a multicentre, randomised controlled study in China (ECP-Core Trial)

Abstract Background The goal of chronic coronary syndrome (CCS) treatment is to improve the function of coronary arteries affected by lesions. Over the past 30 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 still requires quantitative validation. Fractional flow reserve (FFR) is a gold standard (quantitative index) of coronary artery function, and FFR < 0.80 is regarded as an indicator for percutaneous coronary intervention (PCI) in clinical decision-making. However, FFR is an invasive examination, and the interval between the two tests is too short; 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 CCS, and further enhance the long-term prognosis of CCS. Methods This prospective, multicentre, randomised controlled trial is blinded to the examination executors and analysts. 118 participants will be recruited, and they will be divided into the EECP and control groups. The primary outcome of this study is FFR CT . The secondary outcomes include △FFR CT , wall shear stress, axial plaque stress, myocardial perfusion imaging, late gadolinium enhancement, global work index, global work efficiency, total exercise time, time to 1 mm ST-segment depression, cardiac power output, Seattle Angina Questionnaire score, and cardiovascular-related composite endpoint events. Discussion 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 myocardial perfusion, exercise capacity, symptom changes, and prognosis. Therefore, this will potentially provide reliable evidence to inform treatment strategies for CCS. Trial registration: Trial registration number: ChiCTR2400079915. Registered on January 16, 2024 (retrospectively registered), https://www.chictr.org.cn/about.html.