Study objectives:~To determine the optimal timing of non-infarct related artery (IRA) percutaneous coronary intervention (PCI) with the aid of FFR (fractional flow reserve) (immediate complete revascularization during primary angioplasty vs. staged procedure for non-IRA PCI) in patients with ST-segment elevation myocardial infarction with multivessel disease (MVD).~Study hypothesis:~Complete revascularization (CR) at index procedure is not inferior to staged in-hospital CR in patients with STEMI and MVD who undergoing FFR-guided revascularization for non-IRA.~Background:~Multivessel coronary artery disease (MVD) is a common clinical condition, about 40-65% of all primary angioplasty, encountered by interventional cardiologists in ST-segment elevation myocardial infarction (STEMI), and it is associated with poorer clinical outcomes than single-vessel disease. Older guidelines recommended culprit-vessel only revascularization (CVR) during primary angioplasty, except in patient that are hemodynamically unstable. Several recent studies have reported improved clinical outcomes in these patients with multivessel percutaneous coronary intervention (PCI), and others reported promising results from CVR followed by elective second-stage PCI at non-infarct related artery (non-IRA) with significant stenosis. However, there has been no consensus of optimal revascularization strategy in this circumstance.~Recently, several large-scaled randomized controlled trials were conducted about this issue, and confirmed the benefit of immediate complete revascularization during primary angioplasty compared to CVR. Furthermore, fractional flow reserve (FFR)-guided PCI at non-IRA was more effective than angiography-guided PCI at non-IRA for reducing repeat revascularization by either immediate multivessel PCI strategy or staged PCI strategy in the other trials.~Although FFR is a well-known tool to evaluate significant ischemia of moderate stenosis, the most studies regarding FFR enrolled patients without acute myocardial infarction (AMI). Timing of non-IRA PCI is also uncertain. After promising results of above-mentioned randomized trials, current guideline recommendation of multivessel PCI (immediate or staged) was upgraded. However, current guidelines simply mentioned about the timing of non-IRA PCI which recommends complete revascularization during initial hospitalization by either of immediate of staged PCI strategy.~Therefore, the investigators planned to perform prospective, open-label, multicenter, non-inferiority trial to evaluate the efficacy and safety of immediate complete revascularization (PCI for both IRA and non-IRA during primary angioplasty) compared to staged PCI strategy of non-IRA (primary angioplasty for IRA followed by non-IRA PCI after several days). PCI procedure at non-IRA with diameter stenosis between 50 and 70% should be conducted with the aid of FFR, and non-IRA with diameter stenosis ≥ 70% will be revascularized without FFR.~Study procedure:~Patients will be randomized after primary PCI for IRA. Non-IRA lesion which have equal or more than 70% diameter stenosis by visual estimation will be revascularized without FFR evaluation. Non-IRA lesion with diameter stenosis 50-70% by visual estimation will be evaluated using FFR device. In case of FFR value more than 0.8, non-IRA lesion wll be deferred without PCI. If FFR value was equal or less than 0.8, non-IRA lesion will be revascularized.
Patients with STEMI (ST-segment elevation myocardial infarction) with multivessel disease which have PCI (percutaneous coronary intervention)-suitable non-IRA (infarct related artery) will be randomized to immediate complete revascularization group or staged revascularization group by 1:1 fashion. Non-IRA lesion which have equal or more than 70% diameter stenosis by visual estimation will be revascularized without FFR (fractional flow reserve) evaluation. Non-IRA lesion with diameter stenosis 50-70% by visual estimation will be evaluated using FFR device. In case of FFR value more than 0.8, non-IRA lesion wll be deferred without PCI. If FFR value was equal or less than 0.8, non-IRA lesion will be revascularized.