Acute coronary syndromes (ACS) are frequently associated with multivessel coronary artery disease (CAD), and current guidelines recommend complete revascularization beyond the culprit lesion. Angiography-guided PCI is the standard approach, but anatomical assessment does not always reflect the functional significance of intermediate lesions, while FFR-guided strategies are limited by the need for pressure wires and hyperemia. Murray-law-based quantitative flow ratio (μFR) is a wire-free angiography-derived physiological index that may improve decision-making for revascularization in ACS patients.
The Core-μFR is an investigator-driven, multicenter, randomized, open-label and prospective trial designed to evaluate whether μFR can act as a gatekeeper for complete revascularization in patients with ACS and multivessel disease by identifying non-culprit lesions that truly require PCI.
Patients with ACS (either STEMI or NSTE-ACS) undergoing primary PCI will be considered eligible if they present multivessel CAD on visual assessment with the intention to treat the non-culprit vessel in a staged procedure within the same hospitalization. After the pPCI, eligible patients will be randomized to either group A or group B and μFR will be performed in a blinded fashion with the operator unaware of the functional result. Patients in group A will undergo a staged PCI of all NCVs guided by coronary angiography, as per standard of care. In group B, μFR will be used as a gatekeeper for staged revascularization. Operators will only be informed whether at least one non-culprit vessel is μFR-positive, without disclosure of the specific vessel involved or the μFR values. If at least one non-culprit vessel has μFR ≤0.80, patients will undergo angiography-guided PCI of all non-culprit vessels previously deemed suitable for treatment by visual assessment. If μFR is \>0.80 in all non-culprit vessels, staged PCI will be deferred and the patient will be discharged without further revascularization. Finally, to test the functional reproducibility, a blinded post-hoc μFR assessment will be performed on the baseline angiograms of the staged procedures in all the patients undergoing complete revascularization. Clinical follow-up will be performed at 30 days and 1 year from randomization.
Patients presenting with ACS within 72 hours of successful culprit PCI
at least 50% diameter stenosis by visual assessment
a vessel diameter of at least 2.5 mm
amenable to successful PCI
Cardiogenic shock or severe heart failure (NYHA class ≥III)
Severely impaired renal function: creatinine >2 mg/dl or estimated glomerular filtration rate (eGFR) <30 ml/min/1,73 m²
Allergy to iodine-containing contrast agents which cannot be adequately pre-medicated
Pregnancy or intention to become pregnant during the trial