This trial is designed to associate angiography-based fractional flow reserve (3D-angio-based FFR) values with optical coherence tomography findings in pre- and post-percutaneous coronary intervention in patients with non-ST segment elevation acute coronary syndromes.

Prospective, multicenter, international, no-randomized, single-arm, investigator-initiated study, enrolling up to 200 patients with intermediate to severe coronary stenosis (30-90% diameter stenosis) in patients presenting with NST-ACS requiring coronary angiography assessment.

Patients will receive ad-hoc OCT evaluation of the target vessels and offline 3D-angio-based FFR evaluation.

The primary study parameter is the association between 3D-angio-based FFR values and OCT detected minimum luminal area pre- and post-PCI

Inclusion Criteria:

• 18 years or older
• Presenting with NST-ACS
• At least one coronary vessel with intermediate to severe coronary stenosis (30% to 90% by visual estimation or online QCA)
• Target vessel with a reference vessel diameter (RVD) ≥2.5 and ≤ 5.0 mm as assessed by QCA or visual estimation
• The patient is willing to participate in the study
• Target vessel suitable for OCT imaging

Exclusion Criteria:

• Target vessel with a distal Thrombolysis In Myocardial Infarction (TIMI) flow <3
• Target lesion located within 5.0 mm of vessel origin
• Severe tortuosity
• Chronic total occlusion of the target vessel
• Target lesion is located in or supplied by an arterial or venous bypass graft.
• Impaired renal function (eGFR <30ml/min) *
• Pregnant or breastfeeding patients *
• Patient has a known allergy to contrast medium *
• Contraindication for the use of nitrates *
• Life expectancy <12 months