Cardiovascular magnetic resonance in patients with myocardial infarction: current and emerging applications

In patients with known or suspected myocardial infarction (MI), cardiovascular magnetic resonance (CMR) provides a comprehensive, multifaceted view of the heart. The data, including that from a recent multicenter clinical trial, indicate that delayed-enhancement cardiac magnetic resonance imaging (DE-CMR) is a well-validated, robust technique that can be easily implemented on scanners that are commonly available worldwide, with an effectiveness that clearly rivals the best available imaging techniques for the detection and assessment of acute and chronic MI. When patients present outside the diagnostic window of cardiac troponins, DE-CMR may be especially useful. Moreover, because DE-CMR can uniquely differentiate between ischemic and various nonischemic forms of myocardial injury, it may be helpful in cases of diagnostic uncertainty, such as in patients with classical features of MI in whom coronary angiography does not show a culprit lesion. Even after the diagnosis of MI has been made, CMR provides clinically relevant information by identifying residual viability, microvascular damage, stunning, and right ventricular infarction. In addition, post-MI sequelae, including left ventricular thrombus and pericarditis, are easily identified. Given that quantification of infarct size by DE-CMR is highly reproducible, this technique may provide a useful surrogate end point for clinical trials with appreciable reductions in sample size compared with alternative methods.