Diagnostic and prognostic value of cardiac magnetic resonance imaging in assessing myocardial viability.

Assessment of viability is pivotal to the prognosis of patients with chronic coronary artery disease (CAD) and left ventricular dysfunction. Patients with viable myocardium have a better prognosis with revascularization; however, patients with nonviable myocardium have worse outcomes with higher perioperative morbidity and mortality subsequent to revascularization. Cardiac magnetic resonance (CMR) imaging not only is the current reference standard technique in measuring cardiac chamber size and function and myocardial mass and volume but also provides spatially registered 2- or 3-dimensional data sets in myocardial perfusion and myocardial contrast enhancement in the same imaging session. Late gadolinium enhancement by CMR is the best current technique in discriminating myocardial scar versus viable myocardium. An extensive body of preclinical evidence has validated the detection and characterization of the morphology of infarcted tissue. In clinical studies, infarct characteristics by CMR has demonstrated a strong clinical utility in the prediction of left ventricular functional recovery and patient prognosis. In this paper, we aim to review the current CMR techniques in characterizing the spectrum of myocardial changes because of CAD, in the prediction of myocardial viability, and the current evidence of CMR's role in patient prognosis. In addition, we will also review the current literature comparing the clinical utility of CMR with other established imaging modalities in the assessment of CAD.