Pilot Study on the Effect of Intracoronary Cryotherapy on Stabilization of Vulnerable Plaque at Risk of Rupture

Inclusion Criteria: * Men or women at least 18 years old. * Acute cardiac pain/angina consistent with acute coronary syndrome eligible for coronary angiography meeting one of the following criteria: 1. Non ST-segment elevation myocardial infarction (NSTEMI) with rise/fall of cardiac enzymes (troponin I or T) with at least one value above the 99th percentile of the upper reference limit requiring Percutaneous Coronary Intervention (PCI) within 72 hours from diagnosis 2. Stabilized ST-segment elevation myocardial infarction (STEMI) with at least one value above the 99th percentile of the upper reference limit requiring PCI within \< 12 hours from symptoms onset. 3. Unstable angina with new or worsening angina symptoms over the last 2 weeks requiring PCI within 72 hours. * Patient must have one, two or three-vessel disease in native coronary arteries. * PCI of the culprit lesion on all patients. * At least one lesion meeting the criteria below: 1. Located in a non-culprit vessel, or proximal to the culprit lesion if located in the culprit vessel with at least 10 mm distance from the culprit lesion. 2. Lesion stenosis ≤ 70% of the reference vessel diameter by visual assessment on coronary angiogram. 3. Plaque-level maxLCBI4mm ≥ 325 by NIRS (Near-Infrared Spectroscopy). 4. Plaque burden ≥ 65% by IVUS (IntraVascular UltraSound). 5. Not intended for revascularization based on angiographic criteria and negative physiology assessment (FFR\>0.80 or iFR/RFR\>0.89). 6. Lesion-level balloon to artery ratio \> 1.0. 7. Lesion length ≤ 20 mm. 8. Investigator considers that lesions are accessible. 9. If more than two suitable lesions available, investigator will select two lesions for randomization. * Subject able to consent and has a signed and dated the informed consent form. Exclusion Criteria: * Unstable patients (cardiogenic shock, hypotension needing inotropes, hypoxia needing intubation, refractory ventricular arrhythmias, and IABP). * Patients with ongoing ST-segment elevation myocardial infarction. * Patients that had a procedural complication during the PCI procedure, such as coronary dissection, perforation or a complication that would necessitate immediate and/or unplanned surgical revascularization. * History of Coronary Artery Bypass Graft (CABG) or planned CABG within 12 months after the index procedure. * Known ejection fraction \< 30%. * Known severe valvular heart disease. * Known severe renal insufficiency (eGFR \<30 ml/min/1.72 m2). * Any life-threatening conditions or medical comorbidity resulting in life expectancy \< 12 months. * Participation in any investigational study that has not yet reached its primary endpoint. * Women who are pregnant or lactating, or NOT surgically sterile (tubal ligation or hysterectomy) or NOT postmenopausal for at least 6 months or women with childbearing potential without effective contraception (pill, patch, ring, diaphragm, implant and intrauterine device). Angiographic exclusion criteria: * Visible distal embolization/no-reflow following culprit PCI. * Left main coronary artery disease (visual diameter stenosis \> 50%). * Stent thrombosis/restenosis as a culprit lesion. * Index lesion involving a bifurcation. * Angiographic evidence of severe calcification and/or marked tortuosity of the index vessel and/or lesion.