Imaging and Physiology for Intermediate Left Main Stem Stenosis

Inclusion Criteria:

• age >/= 18 years;
• patients who have an intermediate (40-70% diameter stenosis) lesion located in the LMSand a concomitant significant (>/=70% diameter stenosis) in one of the two majordownstream vessels (the LAD or the LCx). The severity of LMS and downstream lesionswill be assessed by visual estimation of the coronary angiography;
• need of complementary diagnostic work up to ascertain the functional/physiologicalsignificance of the LMS lesion, that is not possible from the analysis of angiographicimages only:
• Intermediate severity of LMS lesion, or angiographic ambiguity;
• Impossibility to conclusively associate the LMS lesion with the patient'ssymptoms/clinical presentation due to confounders introduced by the significantdownstream lesion;
• Impossibility to conclusively determine the severity and functional/physiologicalsignificance of the LMS lesion solely by the visual analysis of the coronaryangiography;
• Impossibility to conclusively determine the relative contribution of the LMSlesion to the ischemic burden determined by non-invasive functional tests due tothe presence of a significant downstream lesion;
• Clinical indication for PCI of the downstream lesion located in the LAD or LCx:
• stable angina unresponsive to optimized medical treatment;
• important ischemic burden (> 10% of myocardial mass in territories supplied bythe diseased vessels);
• Reduced FFR/iFR values indicative of myocardial ischemia with significantpressure gradient across the downstream lesion;
• Acute coronary syndrome without ST elevation or stabilized (>7 days) acutemyocardial infarction;
• Downstream lesion anatomically suited for PCI;
• LMS anatomy suited for PCI, with a low or intermediate SYNTAX score (< 32);
• Lack of contra-indications for second-generation drug-eluting stents and/or use ofdual antiplatelet therapy for at least 6 months.

Exclusion Criteria: Left ventricular ejection fraction £ 40%;

• Renal dysfunction with a glomerular filtration rate £ 45 mL/min;
• Concomitance of right coronary artery occlusion supplied by collateral circulationfrom the left coronary;
• Prior coronary artery bypass graft with at least on patent graft to any vessel of theleft coronary;
• Concomitant significant valvular heart disease;
• The first 7 days of an acute myocardial infarction;
• Downstream lesion located only in branches from the major downstream vessels (e.g.diagonal branches of LAD or obtuse marginal branches of the LCx);
• Downstream lesions located in the distal segments of LAD or LCx;
• Significant tortuosity of the downstream vessels in which difficulty to navigate withthe physiology wire and/or intravascular imaging catheter is anticipated