Special article
Cardiac magnetic resonance assessment of regional ventricular function in ischemic heart disease

Introduction
Prior to the availability of percutaneous coronary intervention (PCI) and thrombolysis (TL), few tools were available to interrupt an acute myocardial infarction (MI) and thereby limit infarct size. Currently, we are faced with making decisions regarding prognosis and the potential risks and benefits of revascularization strategies in patients with recent PCI or TL and an admixture of stunned, infarcted, and normal myocardium. Our understanding of the post-infarction remodeling process has changed significantly in the last decade. Data from the SAVE trial [1] have proven the benefits of angiotensin converting enzyme inhibitor (ACEI) therapy in attenuating the maladaptive remodeling which occurs following moderate or large infarctions. Long term data from this group of patients also demonstrated the importance of left ventricular (LV) size and shape on outcome [2]. In the mid-1990’s, additional support for the benefits of an open infarct-related artery was elucidated [3, 4]. Some of the salutary effects are likely related to delivery of cytokines and signaling factors to the healing ultrastructure of the injured myocardium and border zone of the infarct. In fact, the presence of microvascular obstruction at the infarct core is a predictor of poor myocardial functional recovery and is followed by cardiovascular complications [5-7]. Patients in the early post-infarction period often require multiple imaging modalities to assess cardiac structure and function, infarct size, the status of the coronary arteries, and the location and degree of residual inducible ischemia. Cardiac magnetic resonance (CMR) has emerged as a technique which provides excellent definition of cardiac anatomy and function. CMR can assess both global and regional function accurately and reproducibly. Methods have been developed to perform stress testing in the CMR scanner, and studies of viability and inducible ischemia have been validated in animal models and in patients with coronary artery disease. Recent advances in magnetic resonance perfusion imaging serve to make CMR an ideal noninvasive technique to study patients with ischemic heart disease [8]. Furthermore, new approaches to evaluate the integrity of the microcirculation, particularly microvascular obstruction and perhaps in the future 23Na imaging, can provide novel prognostic information and accurate assessment of infarct size noninvasively. Finally, the potential for evaluating not only...


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