FAMOUS-NSTEMI MRI Sub-Study

BACKGROUND: Non-ST-segment elevation myocardial infarction (NSTEMI) is the commonest type of acute coronary syndrome (ACS) and has a poor long-term prognosis. Guidewire-based coronary pressure measurement of the myocardial fractional flow reserve (FFR) is validated for measuring the severity of a coronary lesion narrowing in patients with stable angina. FFR measurement in patients with a recent ACS has theoretical limitations and is not fully validated. AIM: To prospectively assess heart muscle blood flow and injury with guide-wire based methods at the time of the clinically-indicated angiogram and compare these results with those from a stress perfusion MRI scan in medically-stabilised NSTEMI.. HYPOTHESIS: 1) FFR measured invasively will correspond closely with findings from stress perfusion MRI, 2) MRI will provide clinically-relevant information on heart muscle injury, function and salvage, 3) Guidewire-derived measurements of coronary microvascular function will be associated with the MRI findings. DESIGN: The MRI study will be performed in patients who give informed consent in the FAMOUS-NSTEMI clinical trial (NCT registration 01764334). All of the clinical data for these participants will be available to link with the MRI results.