Validation of vFFR as Compared to FFR to Guide Revascularization of Non-culprit Lesions in STEMI Patients

The FAST STEMI II study is an investigator-initiated, multicenter, single-arm, observational cohort study aiming to include 111 patients presenting with ST-elevation myocardial infarction (STEMI). The study is designed to assess the diagnostic performance of acute-setting angiography-based fractional flow reserve (e.g. vessel fractional flow reserve (vFFR)) for the physiological assessment of intermediate non-culprit lesions, with acute-setting fractional flow reserve (FFR) and acute-setting non-hyperemic pressure ratio (NHPR) (e.g. resting full-cycle ratio (RFR)) as the reference standards. Angiography-based FFR has the potential to guide complete revascularization in STEMI patients with multivessel disease, thereby reducing the need for invasive pressure wires and hyperemic agents. However, dedicated data regarding the diagnostic performance of acute-setting angiography-based FFR, with acute-setting FFR and NHPR as the reference standards, is currently lacking for this subset of patients. Of note, FFR slightly underestimates the hemodynamic significance of non-culprit lesions in the acute setting due to microvascular constriction and a blunted hyperemic response, while NHPR slightly overestimates the functional lesion significance. Angiography-based fractional flow reserve is not affected by changes in the microvasculature. Potential discrepancies between acute-setting angiography-based FFR, FFR and NHPR might be explained by the microvascular state, expressed as coronary flow reserve (CFR) and the index of microvascular resistance (IMR). Main objectives: 1. To study the diagnostic performance of acute-setting vFFR for the physiological assessment of intermediate non-culprit lesions in STEMI patients, with acute-setting FFR as the reference standard. 2. To study the diagnostic performance of acute-setting vFFR for the physiological assessment of intermediate non-culprit lesions in STEMI patients, with acute-setting RFR as the reference standards. 3. To study the impact of CFR and IMR on the potential discrepancies between acute-setting vFFR, FFR and RFR.