Fractional Flow Reserve Versus Angiographically Guided Management to Optimise Outcomes in Unstable Coronary Syndromes

Background: In patients with acute non-ST elevation myocardial infarction (NSTEMI) coronary arteriography is usually recommended however visual interpretation of the coronary angiogram is subjective. A complementary diagnostic approach involves measuring the pressure drop across a coronary stenosis (fractional flow reserve, FFR) with a pressure-sensitive guidewire. Hypothesis: Routine FFR measurement is feasible in NSTEMI patients and has additive diagnostic, clinical and health economic utility, as compared to angiography-guided standard care. Design: A prospective multi-center randomized controlled trial in 350 NSTEMI patients with ≥1 coronary stenosis ≥30% severity (threshold for FFR measurement). Patients will be randomized immediately after coronary angiography to the FFR-guided group or angiography-guided group (FFR measured, not disclosed). All patients will then undergo FFR measurement in all vessels with a coronary stenosis ≥30% severity. FFR will be measured in culprit and non-culprit lesions in all patients. FFR will be disclosed to guide treatment in the FFR guided-group but not disclosed in the \'angiography-guided\' group. In the FFR-guided group, an FFR\>0.80 will be an indication for medical therapy whereas an FFR≤0.80 will be an indication for revascularization by percutaneous coronary intervention (PCI) or coronary artery bypass surgery (CABG), as appropriate. The primary endpoint is the between-group difference in the proportion of patients allocated to medical management compared to revascularization. A key secondary composite outcome is the occurrence of cardiac death or hospitalization for myocardial infarction or heart failure. Other secondary outcomes include quality of life, hospitalization for unstable angina, coronary revascularization or stroke, and healthcare costs. Exploratory analyses will also assess the relationships between FFR and angiographic lesion characteristics (severity, culprit status). The minimum and average follow-up periods for the primary analysis are 6 and 18 months respectively. A secondary analysis with longer term follow-up (minimum 3 years) is planned. Screen failures who gave informed consent will be entered into a registry. Importance: Our developmental clinical trial will address the feasibility of FFR measurement in NSTEMI and the influence of FFR disclosure on treatment decisions and health and economic outcomes.