Diagnostic value of routine clinical parameters in acute myocardial infarction: a comparison to delayed contrast enhanced magnetic resonance imaging.

Contrast enhanced magnetic resonance imaging (ceMRI) has advanced to a well accepted diagnostic tool for the identification of acute and chronic myocardial infarction. There is now a large body of evidence that, after the application of a gadolinium based extracellular contrast agent, areas with high signal intensity (enhancement), using a Tl weighted inversion recovery gradient echo technique, represent infarcted necrotic myocardium when compared to histology [1], scintigraphic imaging [2–5] and improvement of wall motion after revascularization [6, 7]. In comparison, normal, stunned and hibernating myocardium do not enhance and can therefore be regarded as non-necrotic myocardium. Due to the high spatial resolution of MR, evaluation of the transmural extent of infarction in addition to its pure existence is possible. In both, acute and chronic infarction, there is a good correlation of the transmurality and the likelihood of contractile improvement after revascularization [6, 7]. Even very small infarcts can be detected, which for example may occur after balloon angioplasty [8]. Such defects may be missed by SPECT or PET [4, 9]. In the present issue of this journal Petersen et al. present a study comparing the value of routine clinical markers for the diagnosis of acute myocardial infarction to ceMRI. In 24 patients with known myocardial infarction (invasive coronary angiography) enhancement was always found in the territory of the infarct related artery suggesting, that ceMRI correctly identified the location of the infarct, a moderate correlation between mass of hyperenhancement and peak creatine kinase (CK) (r 1⁄4 0.65) or between hyperenhancement and endsystolic volume index (ESVI) (r 1⁄4 0.55) and a moderate inverse correlation to ejection fraction (EF) (r =)0.50). Additionally, no relationship between transmurality defined by ceMRI and the development of early ST-elevation or late Q-waves were found. They conclude, that ceMRI, due to its good spatial resolution is the better tool to define transmurality of infarction and may identify small areas of infarction that may be missed by ECG. This study adds important additional evidence that ceMRI is feasible in patients with acute myocardial infarction and that direct visualisation of the infarct is more accurate than the routine clinical markers used in the early and late assessment of patients presenting with acute myocardial infarction.