NSTE-ACS represents the most frequent indication for coronary angiography and percutaneous coronary intervention (PCI) worldwide. PCI permit to reestablished coronary flow but effectiveness of PCI within thrombus containing lesions is limited by the risk of occurrence of distal embolization and no-reflow phenomenon. Distal embolization lead to coronary microcirculation lesions. This complication is related to poor prognosis.

MGuard stent is a stainless-steel closed cell stent covered with an ultra-thin polymer mesh sleeve, which allows to prevent distal embolization during percutaneous coronary intervention in ST-segment-elevation myocardial infarction.

Index of microcirculatory resistance (IMR) is a validated method to assess coronary microcirculation.

Accordingly, the purpose of this study is to demonstrate that MGuard micronet mesh-covered stent prevent distal embolization and microvascular reperfusion impairment during primary PCI, compared with a bare metal stent (BMS) and drug eluting stent (DES) in patients with NSTE-ACS, assessed by Index of microcirculatory resistance.

GUARDIANCORY study is a multicentre, prospective, randomized, non inferiority, open-label trial with a planned inclusion of 52 patients with STE and NSTE ACS and prescribed PCI. Patients will be randomized to benefiting either DES /BMS implantation (n=26) or MGuard stent (n=26) on the culprit lesion. Assessment of coronary microcirculation will be done by IMR immediately after PCI by using a pressure-temperature sensor-tipped coronary wire, thermodilution-derived.

Inclusion Criteria:

• Age > 18 years
• Patients affiliated to social security
• Patients with an NSTEMI or STEMI (1)
• Thrombus containing coronary lesions on angiography (TIMI thrombus grade ≥ 3)
• Eligible patients for revascularization with angioplasty
• Patients consenting to participate in the study.

Exclusion Criteria:

• Age < 18 years
• Prior myocardial infarction
• Prior CABG
• Inability to comply with the protocol
• Major patient protected by law (article L1121-8),
• Person deprived of liberty (article L1121-8),
• Pregnant woman
• Breastfeeding women
• Patient with terminal illness,
• Terminal Renal failure
• Allergy to iodine
• Adenosine's contraindications: Asthmatic patients, Second- or third-degree AV block without a pacemaker or sick sinus syndrome. Systolic blood pressure less than 90mmHg. Recent use of dipyridamole or dipyridamole-containing medications, Methyl xanthenes such as aminophylline caffeine or theobromine block the effect of adenosine and should be held for at least 12 hours prior to the test. Known hypersensitivity to adenosine. Unstable acute myocardial infarction or acute coronary syndrome.