*3.1.3. Statistical analysis*

We examined patients with STEMI and multivessel CAD undergoing primary PCI. Between October 2011 and October 2014 in our 24 h catheterization laboratory randomized 136 patients with multivessel CAD (defined as ≥70% diameter stenosis of two or more epicardial coronary arteries or their major branches by visual estimation with diameter ≥2.5mm). Inclusion criteria were (1) Subject must be at least 18 years of age; (2) Subject is able to verbally confirm under‐ standings of risks and benefits of treatment of either multivessel stenting or staged PCI using the zotarolimus‐eluting stent (Resolute Integrity™ Stent, Medtronic) and he or she or his or her legally authorized representative provides written informed consent prior to any study‐related procedure; (3) Subject must have significant stenoses (≥70%) of two or more than two coronary arteries and requiring primary PCI for acute ST elevation myocardial infarction (STEMI) within 12 h; (4) Target lesions must be located in a native coronary artery with visually estimated diameter of less than 2.5 mm and more than 4.0 mm; (5) Target lesion(s) must be amenable for

Exclusion criteria were as follows: (1) Single lesions; (2) Acute heart failure Killip III‐IV; (3) ≥50% left main stenosis; (4) Small vessels' diameter (<2.5mm); (5) The patient has a known hypersen‐ sitivity or contraindication to any of the following medications: heparin, aspirin, clopidogrel or ticagrelor, zotarolimus. Included were patients with the presence of prolonged (more than30min) chest pain, started less than 12 h before hospital arrival and ST elevation of at least 1 mm in two

Procedure success was defined as the achievement of an angiographic residual stenosis of less than 20% and a thrombolysis in myocardial infarction (TIMI) flow grade 3 after treat‐ ment of the lesions. Before the procedure patients were treated with loading doses of aspirin, clopidogrel or ticagrelor, unfractioned heparin. Post‐PCI medical oral treatment included aspirin, statins, and clopidogrel or ticagrelor, which was recommended for 12 months in all cases after second‐generation zotarolimus‐eluting stent implantation. Signed informed con‐ sent for primary PCI and for the study was obtained from all patients before the procedure. Soon after every diagnostic angiography, the eligible patients were randomly allocated to two different strategies: 1. Multivessel stenting in primary PCI (MS primary): the IRA was opened followed by dilatation of other significantly narrowed arteries during the same pro‐ cedure. 2. Multivessel stenting in staged revascularization (MS staged): the IRA only was treated during the primary intervention while the complete revascularization was planned in a second procedure (10.1 ± 5.1 days). The study protocol conforms to the ethical guidelines of the 1975 Declaration of Helsinki and was approved by the institution's human research

Clinical and procedural data were collected by reviewing hospital records and angiographic runs stored in DICOM CDs. The primary endpoint of the study was the incidence of major adverse cardiac events (MACE) defined as cardiac or noncardiac death, reinfarction, and repeat coronary revascularization. For repeat revascularization we included all PCI or CABG occur‐ ring after the baseline procedure and justified by recurrent symptoms, reinfarction, or objective

or more contiguous limb electrocardiographic leads or 2 mm in precordial leads.

percutaneous coronary intervention.

20 Interventional Cardiology

committee.

*3.1.2. Definitions and endpoints*

Continuous variables are presented as mean ± SD, categorical variables as percentages. For the endpoint "death" patients were censored at death or December 2015 if alive. For MACE patients were censored at the date of first MACE or at the end of follow‐up. Follow‐up was 100% complete. We used Chi Squared and Mann Whitney "U" test for statistical analysis to compare clinical, demographic, angiographic, PCI characteristics, and outcomes in groups. All analyses were performed using STATISTICA 8.0 (StatSoft, Tulsa, OK, USA).