Authors: N Selcuk Yelgec Steven Dymarkowski Javier Ganame Jan Bogaert
Publish Date: 2007/03/15
Volume: 17, Issue: 9, Pages: 2211-2217
Abstract
The diagnosis of myocarditis is difficult and is generally one of exclusion Moreover endomyocardial biopsy EMB is not a sensitive technique Magnetic resonance imaging MRI however has shown promising results in diagnosing myocarditis We evaluated 20 patients with a clinical suspicion of acute myocarditis Troponin I levels were elevated in 17/20 patients Cardiac catheterization n = 13 showed no evidence of coronary artery disease while normal findings were reported in all five patients who underwent EMB MRI performed 98 ± 75 days after the onset of symptoms showed an LVEDV of 172 ± 50 ml and LVEF of 57 ± 10 Abnormalities on delayed contrastenhanced MRI were found in 15/20 patients involving 37 ± 21 segments using the 17segment model The lateral LV wall was most frequently involved 61 of enhanced segments The enhancement was most frequently subepicardial less often transmural or midwall respectively 67 22 and 11 of enhanced segments Mild to moderate systolic wall motion abnormalities were invariably found in the abnormally enhancing myocardium on MRI Associated pericardial effusion was found in six pericardial enhancement in nine patients In conclusion the present study suggests an important role for MRI in evaluating patients with clinical suspicion of acute myocarditis Not only can the myocardial damage be precisely depicted but also concomitant involvement of the pericardium and impact on regional and global ventricular function can be assessedThe diagnosis of myocarditis remains difficult Myocarditis is rarely recognized clinically mainly because of lack of specific clinical signs and the diagnosis is generally one of exclusion 1 Myocarditis is basically an inflammation of the cardiac muscle associated with necrosis of adjacent myocytes but different from those seen after ischemic changes Dallas criteria for classification 1 It is most commonly caused by viral infections but may also result from hypersensitivity trauma radiation and chemical and physical agents 2 Endomyocardial biopsy EMB is still considered the reference technique for diagnosis of myocarditis However there remain many limitations with EMB For example in the Myocarditis Treatment Trial assessing 2233 patients with unexplained heart failure the EMB criteria for active myocarditis were only met in 9 of patients 3 Myocarditis usually presents not as a generalized but as a focal or patchy inflammation often not involving the right ventricle thus questioning the value of a right ventricular EMB 4 Moreover some patients have purely humoral and cytokine mediated forms of myocarditis with little or no cellular infiltrate Even in postmortem hearts with proven myocarditis the probability to meet the Dallas criteria with one biopsy is only 17–28 and with more than five biopsies approximately twothirds of patients met the Dallas criteria 1 3Clearly EMB is not a sensitive diagnostic tool with a very high false negative rate emphasizing the need for more accurate preferably noninvasive methods to diagnose myocarditis Among these antimyosin scintigraphy and Gallium67 imaging have shown promise in detecting myocyte injury However these methods have low specifity and low positive predictive values 5 Echocardiography has a limited role in the diagnosis of myocarditis but it can help to identify with fulminant myocarditis at presentation These patients generally have thickened myocardial walls due to edema In some patients this increase in wall thickness may mimic hypertrophic cardiomyopathy in early course of the disease Echocardiographic analysis of changes in myocardial texture in acute myocarditis is a new but not yet established approach Recently magnetic resonance imaging MRI and also multidetector computed tomography have shown promising results in the diagnosis and followup of myocarditis 4 6 7 8 9 10 11 12 13 The aim of the present study was to assess the MRI findings and relate them to the clinical technical and other imaging findings in patients with a clinical suspicion of acute myocarditis
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