Table 4. Single endpoints definitions.

Endpoints definitions	Description
Device success	All of: • Successful delivery, balloon expansion, and deployment of the first assigned device, at the intended target lesion/bifurcation. When deployment of >1 assigned device is planned in advance for a single bifurcation lesion (eg, a 2-stent technique), all assigned devices are assessed and reported as 1 device. In that case, only when all assigned devices are successfully implanted at the intended target lesion is this classified as device success. (Multiple attempts using the same instrument are allowed; for example, success at a second attempt with the same [first] investigational device after rewiring the vessel, use of a support catheter, or additional ballooning, vessel preparation, etc). • Successful withdrawal of the device delivery system. • Attainment of a final in-stent or in-scaffold residual stenosis of <30% (or <50% in case of balloon angioplasty alone) with final data reported by core laboratory QCA using dedicated bifurcation software (preferred methodology when no intravascular imaging is provided wsee Supplemental Appendix])
Cardiovascular death	1. Death caused by acute MI 2. Sudden cardiac, including unwitnessed, death 3. Death resulting from heart failure 4. Death caused by stroke 5. Death caused by cardiovascular procedures 6. Death resulting from cardiovascular hemorrhage (hemorrhage deriving from cardiac and/or vascular disease/injuries)
Periprocedural MI	Evaluation <48 h: • hs-cTn T rise ≥35 URL AND ≥1 of the following criteria: • “Flow-limiting” angiographic complications in a major epicardial vessel (RefD ≥2. 0 mm evaluated by core-lab QCA), at the end of the procedure • New significant Q waves (or equivalent) in 2 contiguous leads, after the procedure • A new wall motion abnormality on echocardiography, after the procedure OR • hs-cTn T rise ≥70 URL (All events should be adjudicated, ideally after core-lab analysis, by an independent CEC)
Cardiac biomarkers rise67	Any CK-MB and/or hs-cTn T rise >6 h after the procedure Type 1: due to SB occlusion a) Intraprocedural, after lesion predilation b) Intraprocedural, after device (stent, scaffold) implantation c) Final result at the end of the procedure Type 2: due to other angiographic complications a) Intraprocedural occlusion of the main branch b) Intraprocedural distal embolization c) Intraprocedural coronary perforation d) Intraprocedural dissection (after predilation, after device implantation) e) Residual dissection at the end of the procedure f) Intraprocedural thrombus g) Residual thrombus at the end of the procedure Type 3: No angiography identifiable causes
Stroke	Neuro-ARC definitions (according to ARC-2 criteria)
Bleeding	BARC definitions (according to ARC-2 criteria)
Target bifurcation-related ischemia	The target bifurcation ischemia is defined in presence of ischemic myocardium supplied by the bifurcation coronary segments treated during the initial procedure. Identification and localization of ischemia requires the use of the same ischemic test, utilized during the inclusion in the study.
Target bifurcation revascularization	The target bifurcation lesion is commonly considered as the treated coronary segment during the index procedure plus 5 mm distance from the stent edges or the balloon angioplasty site, applied both for MV and SB in case of bifurcation lesions. When an SB does not undergo either balloon angioplasty or stent placement at the time of the index procedure, but at the time of angiographic follow-up (either mandated or clinically indicated) has developed a stenosis (%DS ≥50 according to bifurcation QCA) Bif-ARC considers that the region extending up to a 5 mm distance from the ostium of the SB should be included within the target bifurcation definition. Target bifurcation revascularization is defined as a repeat percutaneous intervention of the target bifurcation or bypass surgery of the target vessel performed for restenosis or other complication of the target bifurcation. MEDINA classification of the newly diseased bifurcation segments and the repeat revascularized segments is recommended.
Target vessel revascularization	The target vessel is defined as the entire major intervened coronary vessel, including side branches. In case of LM-LAD/Circ bifurcation treatment, LM-LAD lesion without significant stenosis in LCx / target vessel: LM-LAD only; otherwise LM, LAD, LCx Target vessel revascularization is defined as any repeat percutaneous intervention or surgical bypass of any segment of the target vessel including the target bifurcation.
Target vessel nontarget bifurcation revascularization	Target vessel nontarget bifurcation revascularization is defined as any repeat percutaneous intervention or surgical bypass of the target vessel for pre-existing disease, disease progression, or other reasons unrelated to the target lesion as defined above.
Target bifurcation-related MI	Any MI with angiographic confirmation of culprit lesion corresponding to the target bifurcation previously treated Nonconfirmed bifurcation related MI should be considered as target vessel MI
Definite stent thrombosis	Angiographic confirmation: the presence of a thrombus that originates in the stent or in the segment 5 mm proximal or distal to the stent or in the side branch originating from the stented segment and the presence of at least 1 of the following criteria: 1) Acute onset of ischemic symptoms at rest 2) New electrocardiographic changes suggestive of acute ischemia 3) Typical rise and fall in cardiac biomarkers (refer to definition of spontaneous myocardial infarction) OR Pathological confirmation: 1) Evidence of recent thrombus within the stent determined at autopsy 2) Examination of tissue retrieved following thrombectomy (visual/histology) Early acute: 0-24 h; early subacute: 1 d-30 d; late: 30 d-1 y; very late: >1 y
Probable stent thrombosis	Regardless of the time after the index procedure, any myocardial infarction that is related to documented acute ischemia in the territory of the implanted stent without angiographic confirmation of stent thrombosis and in the absence of any other obvious cause Early acute: 0-24 h; early subacute: 1 d-30 d; late: 30 d-1 y; very late: >1 y
SB occlusion	SB flow impairment: SB TIMI flow less than main vessel TIMI flow after procedure SB occlusion: loss of angiographic visualization of SB PMV TIMI flow 0-1: SB flow not assessable
MV occlusion	PMV or DMV: 1) When TIMI flow grade 3 or 2 at baseline; TIMI flow grade 0 or 1 after the procedure 2) When TIMI flow grade 1 at baseline; TIMI flow grade 0 after the procedure 3) When TIMI flow grade 0 at baseline and vessel patency (TIMI flow grade 2 or 3) established during procedure; TIMI flow grade 0 after procedure
Major dissection (angiographic)	Dissection in the target vessel greater than Type b from National Heart, Lung, and Blood Institute classification110
Perforation	Type 1) extraluminal crater without jet extravasation Type 2) pericardial or myocardial blushing without jet extravasation Type 3) active jet extravasation exit jet >1 mm Type 4) leaking into another cardiovascular cavity Type 5) distal perforation
Late lumen loss or gain	Difference between the MLD immediately after the procedure and the MLD at follow-up
Binary stenosis	>50 %DS at follow-up
ARC: Academic Research Consortium; Bif-ARC: Bifurcation Academic Research Consortium; CEC: clinical event committee; CK-MB: creatine kinase-MB; DMV: distal main vessel; hs-cTn: high- sensitivity cardiac troponin; LCx: left circumflex artery; LAD: left anterior descending artery; LM: left main; PMV: proximal main vessel; URL: upper reference limit; other abbreviations as in Tables 1 to 3.