Background: Coronary microvascular dysfunction (CMD) predicts mortality after ST‐elevation–myocardial infarction (STEMI). Arginine vasopressin (AVP) may be implicated, but data in humans are lacking, and no study has investigated the link between arginine vasopressin and invasive measures of CMD. Methods and Results: We invasively assessed CMD in 55 patients with STEMI treated with primary percutaneous coronary intervention (PPCI), by measuring the index of microcirculatory resistance after PPCI. In a separate group of 45 patients with STEMI/PPCI, recruited for a clinical trial, we measured infarct size and microvascular obstruction with cardiac magnetic resonance (CMR) imaging at 1 week and 12 weeks post‐STEMI. Serum copeptin was measured at 4 time points before and after PPCI in all patients with STEMI. Plasma copeptin levels fell from 92.5 pmol/L before reperfusion to 6.4 pmol/L at 24 hours. Copeptin inversely correlated with diastolic, but not systolic, blood pressure (r=−0.431, P =0.001), suggesting it is released in response to myocardial ischemia. Persistently raised copeptin at 24 hours was correlated with higher index of microcirculatory resistance (r=0.372, P =0.011). Patients with microvascular obstruction on early CMR imaging showed a trend toward higher admission copeptin, which was not statistically significant. Copeptin levels were not associated with infarct size on either early or late CMR. Conclusions: Patients with CMD after STEMI have persistently elevated copeptin at 24 hours, suggesting arginine vasopressin may contribute to microvascular dysfunction. Arginine vasopressin receptor antagonists may represent a novel therapeutic option in patients with STEMI and CMD.

Background: Human cytomegalovirus is a herpes virus that affects most individuals globally and may increase the risk of cardiovascular disease. Whether cytomegalovirus influences outcomes after ST‐segment–elevation myocardial infarction (STEMI) is unknown. Our objective was to investigate the association between latent cytomegalovirus infection and outcomes after STEMI. Methods: This study includes 354 patients with STEMI who were recruited to T‐TIME (A Trial of Low‐Dose Adjunctive Alteplase During Primary PCI) and had blood samples cryopreserved. Participants underwent immediate percutaneous coronary intervention, serial cardiovascular magnetic resonance imaging at 2 to 7 days and 3 months post‐STEMI, and assessment of health‐related quality of life with the EuroQol 5‐Dimension visual analog scale. Cytomegalovirus Ig (immunoglobulin) G titer was measured in cryopreserved baseline samples from each patient. Results were adjusted for age and other possible confounders. Results: One hundred seventy‐five patients (49.4%) were cytomegalovirus IgG titer‐negative, 89 (25.1%) were low‐positive, and 90 (25.4%) were high‐positive. Patients who were cytomegalovirus‐positive were older (62.5 versus 58.7 years of age) and more likely to be non‐White (6.7% versus 2.3%). Myocardial reperfusion, measured by ST‐segment resolution, was less successful in patients who were cytomegalovirus‐positive (38.7% resolution versus 48.4%; adjusted P =0.032). Left ventricular ejection fraction was lower in patients who were cytomegalovirus‐positive in the first week (42.6% versus 45.3%; adjusted P =0.006) and at 3 months (47.8% versus 49.7%; adjusted P =0.033). Over 3 months, patients who were cytomegalovirus‐positive had less improvement in health‐related quality of life (change in EuroQol 5‐Dimension visual analog scale: +3.38 versus +9.93; adjusted P <0.001). Conclusions: Patients who are cytomegalovirus‐positive with STEMI have impaired reperfusion, reduced left ventricular function, and less improvement in health‐related quality of life over 3 months.

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.