[Beta-blockers after myocardial infarction with preserved systolic function: useful or redundant?]

Given the lack of adequately sized randomized clinical trials (RCTs) testing the value of maintenance beta-blockers for post-myocardial infarction (MI) patients without reduced left ventricular ejection fraction and treated according to current standards, several observational studies have tried to address this highly relevant issue. However, results from observational studies have yielded opposite conclusions, with some suggesting that beta-blockers are associated with clinical benefit and others suggesting that they have no benefit. Due to the observational nature of these studies, the risk of bias is very high. In particular the existence of a confounding by indication factor is present when the prescription of the therapy is not random and is instead based on patients' clinical characteristics. Some randomness is needed to ensure that individuals with identical characteristics can be observed in both states (with or without beta-blockers). The only chance, therefore, to solve the question of benefits of beta-blockers is the execution of adequately sized RCTs. Currently, four large RCTs are ongoing in Europe, and, among them, the REBOOT-CNIC trial is already beyond three quarters of the expected cohort to be enrolled (6000/8648 revascularized MI patients without left ventricular dysfunction). An Italian cohort (1800 patients) will be included, enrolled by the Italian REBOOT Network. Enrollment is expected to be complete by the end of 2022, and the first results will become available by the end of 2025.