This study is prospective, randomized, multicentre, open label study in patients with ST elevation myocardial infarction (STEMI) with multivessel coronary artery disease (MVD) defined as >70% stenosis in a non-culprit vessel, initially treated with culprit only primary PCI. The patients will be enrolled in four high volume PCI centers after successful culprit only primary PCI and then randomly assigned to one of three treatment arms:1. complete revascularization of all non-culprit significant lesions in a single session during initial hospitalization; 2. same revascularization in a single session after 30 days; 3.revascularization or it's deferral based on ischemia testing using Dobutamin stress echocardiography. The study will explore differences in occurrence of major adverse cardio-cerebral events (cardiac death, repeated myocardial infarction, cerebrovascular accident and repeated revascularization) and complications of interventions during 12 months follow-up.