Inhibition of late sodium current (INa) to prevent coronary MICROvascular dysfunction in patients presenting with ST-elevation myocardial infarction and multivessel disease: A phase IIb multicenter, randomized, controlled and open label study (INaMICRON)

INTRODUCTION: Residual coronary microvascular dysfunction (CMD) is common after STEMI despite successful primary PCI and may contribute to ongoing ischemia and impaired recovery. INaMICRON will test the hypothesis that early late I METHODS AND RESULTS: INaMICRON is a prospective, multicenter, randomized (1:1), open-label phase IIb trial enrolling adults with STEMI treated with successful primary PCI and at least one significant non-culprit lesion suitable for staged PCI. Participants will be randomized to standard therapy plus ranolazine (500 mg bid for 7 days, then 750 mg bid up to 42 ± 7 days) or standard therapy alone. Coronary microvascular function will be assessed using IMR and/or angioIMR in the culprit vessel after primary PCI (baseline) and during staged PCI (follow-up); non-culprit vessel physiology will also be assessed during the staged procedure. Complementary evaluations include peripheral endothelial function testing (EndoPAT), a single CMR at 42 ± 7 days, and paired blood sampling for translational multi-omics analyses. The planned sample size is 100 patients (50 per group), and analyses will compare between-group differences in physiology and related measures and explore predefined correlations. The study is designed to estimate the magnitude of microvascular modulation in the experimental group. CONCLUSIONS: This trial will provide feasibility data and an estimate of the magnitude of microvascular modulation achievable with early ranolazine after STEMI, informing the design of larger outcome-oriented studies and future precision approaches to post-MI care.