Abstract
BACKGROUND: Microvascular injury in patients with ST-segment elevation myocardial infarction (STEMI) occurs in up to 50%, yet no therapeutic target exists. Inflammation contributes directly to myocardial damage in STEMI and may also cause deleteriously effects on the microcirculation. The aim of this prespecified sub-study was to determine the effect of prehospital pulse-dose glucocorticoid on the microcirculation determined by index of microvascular resistance (IMR) and its relation to inflammation. The PULSE-MI trial was a 1:1 randomized, blinded, placebo-controlled clinical trial in patients with STEMI transferred for primary percutaneous coronary intervention (PCI) investigating the cardioprotective effects of prehospital pulse-dose glucocorticoid (methylprednisolone 250 mg) compared with placebo. In this prespecified sub-study, we investigated microvascular function as IMR by thermodilution after primary PCI and inflammation defined by C-reactive protein (CRP) at 24 hours after onset of STEMI. RESULTS: Of 530 patients included in the PULSE-MI trial, 295 (56%) were assessed with coronary physiology of whom 142 (48%) were treated with glucocorticoid and 153 (52%) with placebo. Baseline characteristics were overall well-balanced in both groups. The median IMR in the glucocorticoid group was 23 (interquartile range (IQR), 11-38) and 18 (IQR, 11-42) in the placebo group (p=0.49). CRP upon arrival did not differ between treatment groups (p=0.81), but CRP at 24 hours was significantly lower in the glucocorticoid group compared to placebo (p<0.001). CONCLUSIONS: Prehospital glucocorticoid did not impact IMR assessed immediately after primary PCI, albeit this compound, demonstrated significant anti-inflammatory effects as determined by CRP levels at 24 hours. TRIAL REGISTRATION: http://www. CLINICALTRIALS: gov ; Unique Identifier: NCT05462730.