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Background Microvascular obstruction commonly affects patients with acute ST-segment elevation myocardial infarction and is independently associated with adverse outcomes. Objective To determine whether or not a strategy involving low-dose intracoronary fibrinolytic therapy infused early after coronary reperfusion will reduce microvascular obstruction. Design This was a multicentre, randomised, double-blind, parallel-group, placebo-controlled, dose-ranging trial. Setting The trial took place at 11 hospitals in the UK between 17 March 2016 and 21 December 2017. Participants Patients with acute ST-segment elevation myocardial infarction and a symptom onset to reperfusion time of ≤ 6 hours were eligible for randomisation. Radial artery access was a requirement, and further angiographic criteria included a proximal-to-middle coronary artery occlusion or impaired coronary flow in the presence of a definite thrombus in the culprit coronary artery. Exclusion criteria included a functional coronary collateral supply to the infarct-related artery, any contraindication to fibrinolysis and lack of informed consent. Additional exclusion criteria for safety were (1) requirement for immunosuppressive drug therapy for ≤ 3 months and (2) treatment with an antimicrobial agent. Intervention A total of 440 participants were randomly assigned 1 : 1 : 1 to treatment with placebo (n = 151), 10 mg of alteplase (n = 144) or 20 mg of alteplase (n = 145) administered by manual infusion directly into the infarct-related coronary artery over 5–10 minutes. The intervention was scheduled to happen after reperfusion and before stent implantation. Outcomes The primary outcome was the amount of microvascular obstruction (percentage of left ventricular mass) demonstrated by contrast-enhanced cardiac magnetic resonance imaging at 2–7 days after enrolment. The primary analysis was the comparison between the 20 mg of alteplase group and the placebo group; if this comparison was not significant, the comparison of the 10 mg of alteplase group with the placebo group was considered as a secondary analysis. Sample size A total of 618 patients (minimum of 558 patients). Recruitment was halted on 21 December 2017 given that conditional power for the primary outcome based on a prespecified analysis of the first 267 randomised participants was Methods The primary outcome was compared between groups using a stratified Wilcoxon rank-sum test (van Elteren test), stratified by the location of the myocardial infarction. Results Among the 440 patients (mean age of 60.5 years; 15% women), the primary end point was measured in 396 (90%) patients, 17 (3.9%) withdrew, seven died and all other patients were followed up to 3 months. The amount (mean percentage of left ventricular mass) of microvascular obstruction was 2.3% versus 2.6% versus 3.5% in the placebo, 10 mg of alteplase and 20 mg of alteplase groups, respectively. In the primary analysis, microvascular obstruction did not differ between the 20 mg of alteplase group and the placebo group: 3.5% versus 2.3%, estimated difference 1.16% (95% confidence interval –0.08% to 2.41%; p = 0.32). In the secondary analysis, microvascular obstruction did not differ between the 10 mg of alteplase group and the placebo group: 2.6% versus 2.3%, estimated difference 0.29% (95% confidence interval –0.76% to 1.35%; p = 0.74). By 3 months, major adverse cardiac events (cardiac death, non-fatal myocardial infarction and unplanned hospitalisation for heart failure) had occurred in 15 (10.1%) patients in the placebo group, 18 (12.9%) in the 10 mg of alteplase group and 12 (8.2%) in the 20 mg of alteplase group. Conclusions Adjunctive low-dose intracoronary alteplase given during the primary percutaneous intervention did not reduce microvascular obstruction compared with placebo. Limitations Premature discontinuation of enrolment limited the power of the secondary and safety analyses. Future work Low-dose intracoronary alteplase or tenecteplase could be compared with placebo at the end of primary percutaneous coronary intervention in patients with an ischaemic time of Trial registration This trial is registered as ClinicalTrials.gov NCT02257294. Funding This project was funded by the Efficacy and Mechanism Evaluation (EME) programme, a Medical Research Council (MRC) and National Institute for Health Research (NIHR) partnership. This will be published in full in Efficacy and Mechanism Evaluation; Vol. 7, No. 5. See the NIHR Journals Library website for further project information.

Background COVID-19 is typically a primary respiratory illness with multisystem involvement. The prevalence and clinical significance of cardiovascular and multisystem involvement in COVID-19 remain unclear. Methods This is a prospective, observational, multicentre, longitudinal, cohort study with minimal selection criteria and a near-consecutive approach to screening. Patients who have received hospital care for COVID-19 will be enrolled within 28 days of discharge. Myocardial injury will be diagnosed according to the peak troponin I in relation to the upper reference limit (URL, 99th centile) (Abbott Architect troponin I assay; sex-specific URL, male: >34 ng/L; female: >16 ng/L). Multisystem, multimodality imaging will be undertaken during the convalescent phase at 28 days post-discharge (Visit 2). Imaging of the heart, lung, and kidneys will include multiparametric, stress perfusion, cardiovascular magnetic resonance imaging, and computed tomography coronary angiography. Health and well-being will be assessed in the longer term. The primary outcome is the proportion of patients with a diagnosis of myocardial inflammation. Conclusion CISCO-19 will provide detailed insights into cardiovascular and multisystem involvement of COVID-19. Our study will inform the rationale and design of novel therapeutic and management strategies for affected patients. Clinical trial registration ClinicalTrials.gov identifier NCT04403607.

Background Impaired microcirculatory reperfusion worsens prognosis following acute ST ‐segment–elevation myocardial infarction. In the T‐ TIME (A Trial of Low‐Dose Adjunctive Alteplase During Primary PCI) trial, microvascular obstruction on cardiovascular magnetic resonance imaging did not differ with adjunctive, low‐dose, intracoronary alteplase (10 or 20 mg) versus placebo during primary percutaneous coronary intervention. We evaluated the effects of intracoronary alteplase, during primary percutaneous coronary intervention, on the index of microcirculatory resistance, coronary flow reserve, and resistive reserve ratio. Methods and Results A prespecified physiology substudy of the T‐ TIME trial. From 2016 to 2017, patients with ST ‐segment–elevation myocardial infarction ≤6 hours from symptom onset were randomized in a double‐blind study to receive alteplase 20 mg, alteplase 10 mg, or placebo infused into the culprit artery postreperfusion, but prestenting. Index of microcirculatory resistance, coronary flow reserve, and resistive reserve ratio were measured after percutaneous coronary intervention. Cardiovascular magnetic resonance was performed at 2 to 7 days and 3 months. Analyses in relation to ischemic time (P =0.013), resistive reserve ratio ( P =0.026), and microvascular obstruction ( P =0.022), but not index of microcirculatory resistance. Conclusions In ST ‐segment–elevation myocardial infarction with ischemic time ≤6 hours, there was overall no difference in microvascular function with alteplase versus placebo. Clinical Trial Registration URL : https://www.clinicaltrials.gov . Unique identifier: NCT 02257294.

Key Points Question: In patients undergoing primary percutaneous coronary intervention for acute ST-segment elevation myocardial infarction (STEMI), does adjunctive fibrinolytic therapy with low-dose intracoronary alteplase given after reperfusion and before stent implant reduce microvascular obstruction? Findings: In this randomized clinical trial that included 440 participants randomized to receive alteplase 20 mg, alteplase 10 mg, or placebo, the primary analysis demonstrated that the amount of microvascular obstruction (% left ventricular mass) revealed by magnetic resonance imaging was 3.5% in the alteplase 20-mg group and 2.3% in the placebo group, a difference that was not statistically significant. Meaning: Adjunctive low-dose intracoronary alteplase given early during primary percutaneous coronary intervention for acute ST-segment elevation myocardial infarction did not reduce microvascular obstruction. Abstract Importance: Microvascular obstruction commonly affects patients with acute ST-segment elevation myocardial infarction (STEMI) and is associated with adverse outcomes. Objective: To determine whether a therapeutic strategy involving low-dose intracoronary fibrinolytic therapy with alteplase infused early after coronary reperfusion will reduce microvascular obstruction. Design, Setting, and Participants: Between March 17, 2016, and December 21, 2017, 440 patients presenting at 11 hospitals in the United Kingdom within 6 hours of STEMI due to a proximal–mid-vessel occlusion of a major coronary artery were randomized in a 1:1:1 dose-ranging trial design. Patient follow-up to 3 months was completed on April 12, 2018. Interventions: Participants were randomly assigned to treatment with placebo (n = 151), alteplase 10 mg (n = 144), or alteplase 20 mg (n = 145) by manual infusion over 5 to 10 minutes. The intervention was scheduled to occur early during the primary PCI procedure, after reperfusion of the infarct-related coronary artery and before stent implant. Main Outcomes and Measures: The primary outcome was the amount of microvascular obstruction (% left ventricular mass) demonstrated by contrast-enhanced cardiac magnetic resonance imaging (MRI) conducted from days 2 through 7 after enrollment. The primary comparison was the alteplase 20-mg group vs the placebo group; if not significant, the alteplase 10-mg group vs the placebo group was considered a secondary analysis. Results: Recruitment stopped on December 21, 2017, because conditional power for the primary outcome based on a prespecified analysis of the first 267 randomized participants was less than 30% in both treatment groups (futility criterion). Among the 440 patients randomized (mean age, 60.5 years; 15% women), the primary end point was achieved in 396 patients (90%), 17 (3.9%) withdrew, and all others were followed up to 3 months. In the primary analysis, the mean microvascular obstruction did not differ between the 20-mg alteplase and placebo groups (3.5% vs 2.3%; estimated difference, 1.16%; 95% CI, −0.08% to 2.41%; P = .32) nor in the analysis of 10-mg alteplase vs placebo groups (2.6% vs 2.3%; estimated difference, 0.29%; 95% CI, −0.76% to 1.35%; P = .74). Major adverse cardiac events (cardiac death, nonfatal MI, unplanned hospitalization for heart failure) occurred in 15 patients (10.1%) in the placebo group, 18 (12.9%) in the 10-mg alteplase group, and 12 (8.2%) in the 20-mg alteplase group. Conclusions and Relevance: Among patients with acute STEMI presenting within 6 hours of symptoms, adjunctive low-dose intracoronary alteplase given during the primary percutaneous intervention did not reduce microvascular obstruction. The study findings do not support this treatment. Trial Registration: ClinicalTrials.gov Identifier: NCT02257294