To determine whether, on a background of optimal medical therapy, including ticagrelor, opening of all suitable narrowings or blockages found at the time of primary PCI for an acute heart attack is better than treating only the culprit lesion in patients with multi-vessel disease.

To determine if a strategy of multivessel revascularization involving PCI of all suitable non-infarct related artery lesions plus optimal medical therapy is superior to a strategy of optimal medical therapy alone in reducing (1) the composite outcome of cardiovascular (CV) death or new myocardial infarction (MI), or (2) the composite of CV death, new MI or ischemia driven revascularization (IDR) in patients with multivessel disease who have undergone early successful culprit lesion PCI for STEMI.

Inclusion Criteria:

1. Men and women within 72 hours after successful PCI (preferably using a drug eluting stent) to the culprit lesion for STEMI. PCI for STEMI can be either primary PCI or rescue PCI for failed fibrinolysis or a combination strategy where PCI is performed routinely 3-12 hours after fibrinolysis AND

2. Multi-vessel disease defined as at least 1 additional non-infarct related coronary artery lesion that is at least 2.5 mm in diameter that has not been stented as part of the primary PCI and that is amenable to successful treatment with PCI and has:

   • At least 70% diameter stenosis (visual estimation) or
   • At least 50% diameter stenosis (visual estimation) with fractional flow reserve (FFR) ≤ 0.80

Exclusion Criteria:

1. Planned revascularization of non-culprit lesion
2. Planned surgical revascularization
3. Non-cardiovascular co-morbidity reducing life expectancy to < 5 years
4. Any factor precluding 5 year follow-up
5. Prior Coronary Artery Bypass Graft (CABG) Surgery