The role of cardiovascular magnetic resonance in non-ST-elevation-myocardial infarction

Background: myocardial infarction (MI) and its related complications remain the leading cause of death in Switzerland. Non-ST-segment elevation myocardial infarction (NSTEMI) is projecting to double between 2015 and 2030. Since it is a life-threatening situation, current guidelines include ICA is indicated in current guidelines as first diagnostic exam to rule out coronary atherosclerosis but exposing patients to all the risk of an invasive procedure. So, on one hand if ICA is necessary to rule out the need for achieving a complete coronary revascularisation, on the other hand it has been demonstrated how, in more than a third of patients, an alternative diagnosis needs to be considered since ICA is normal. To avoid exposing patients to unnecessary invasive tests, recently an imaging strategy guided by computed tomography angiography (CTA) prior to ICA has proven to be an effective strategy in patients with low or intermediate risk CAD, but only 40% of patients are eligible for this approach. Cardiovascular Magnetic Resonance (CMR) is a non-invasive method that provides information on global and regional cardiac function, presence of myocardial oedema and myocardial scar as well as the presence and extent of inducible ischemia. However, the role of CMR imaging to evaluate the need of an invasive strategy remains unclear in the acute setting, despite its potentials. The present project will explore the effectiveness of a CMR guided strategy in patients diagnosed with NSTEMI with the aim to reach a more personalised approach.Objectives and aims: a) to investigate the reclassification rate, defined as the number of patients in whom the information provided by pre-angiography CMR affects revascularisation strategy or the final diagnosis; b) to evaluate the accuracy of CMR to detect obstructive CAD on ICA in patients with NSTEMI; c) to evaluate whether a CMR guided strategy may reduce the number of patients referred to ICA; e) to evaluate the cost-effectiveness of a CMR guided strategy compared to standard care. Methods: this is a prospective interventional study investigating the role of CMR in NSTEMI. Eligible patients will undergo CMR imaging prior to ICA and the standard of care (SOC) decision-making on revascularization strategy and diagnosis will be declared by the treating physician blinded to CMR results. The treating physician will then be informed about the CMR findings and the CMR-modified SOC and diagnosis will be collected. All CMR will be also analyzed blinded to ICA results in a dedicated core-lab and an external committee will independently elaborate on SOC and CMR-modified SOC and diagnosis. The primary endpoint of the study is CMR-based reclassification rate on revascularisation strategy and diagnosis. Secondary endpoints include the sensibility and specificity of detecting haemodynamically significant obstructive CAD in patients with NSTEMI. Expected results and potential impact for the field: this research provides the first attempt to investigate the impact of CMR, preceding an invasive management for NSTEMI, on resource utilization, treatment strategy and final diagnosis with the ultimate goal to avoid unnecessary ICA and better inform decision making on revascularization in patients with obstructive CAD in the future.