Rationale and Design of a Randomised Proof-of-Concept Trial to Assess the Safety of Early Discharge Using Index Microcirculatory Resistance in Patients with Acute Myocardial Infarction: SECURE Study

Background: Current guidelines acknowledge that early discharge is not associated with late mortality and that in-hospital length of stay (LOS) of 48–72 h should be considered following successful primary percutaneous coronary intervention (PPCI) in low-risk patients. Recent studies have highlighted the safety of very early discharge after PPCI in highly selected low-risk patients; however, objective tools to guide discharge timing remain limited. The Index of Microcirculatory Resistance (IMR) offers a quantitative assessment of microvascular function and may help identify patients suitable for very early discharge. We aimed to evaluate the feasibility of using IMR to guide very early discharge in patients who underwent uncomplicated PPCI. Study design and objectives: The Safety of Early Discharge Using Index Microcirculatory Resistance in Patients with Acute Myocardial Infarction (SECURE) study is designed to assess the feasibility of using IMR, measured immediately following successful PPCI, to guide early discharge from hospital within 24 h. The SECURE study is a prospective, proof-of-concept, functional non-inferiority, single-centre, randomised, open-label trial to determine if patients with low IMR can be safely discharged when compared to standard discharge policy. The SECURE study will recruit 82 patients with low IMR following successful PPCI. Participants will be 1:1 randomised to either standard discharge timing or very early discharge (within 24 h). The left ventricle ejection fraction will be assessed using cardiac magnetic resonance imaging. A telephone follow-up at 3 months will be arranged. Clinical events are collected as secondary and exploratory safety endpoints. Conclusions: The SECURE study will provide proof-of-concept data about the feasibility of using IMR to guide very early discharge following PPCI. If successful, this study will provide data to plan for a larger study to determine the safety of this personalised approach.