Use of Cardiac Magnetic Resonance Imaging to Distinguish Between Acute Myocarditis and Takotsubo Cardiomyopathy

We present a case of a 62-year-old male with pneumonia who presented with chest pain, ECG changes and troponin elevation. His presentation appeared to be consistent with takotsubo cardiomyopathy (TC), however his cardiac magnetic resonance imaging was highly suggestive of acute myocarditis with regional wall motion abnormalities mimicking those of apical TC. A 62-year-old man was admitted with pneumonia. The following day, he developed acute onset chest pain and ECG demonstrated tombstone-like ST segment elevation in the anterior and lateral leads, without reciprocal changes (Figure 1A). He was intubated for acute pulmonary edema. He was treated with thrombolytic therapy for suspected ST elevation myocardial infarction. Upon arrival to our institution, the ST segment elevation had resolved. He was hemodynamically unstable, requiring vasopressor support. His troponin T was 7000 ng/L, peaking at 15300 ng/L after 5 days (normal <14 ng/L) and his creatinine kinase was 3600 U/L, peaking on admission (normal 52-256 U/L). He underwent coronary angiography which revealed non-obstructive coronary artery disease in the right coronary artery and no evidence of plaque rupture. His ventriculography (LV gram) and transthoracic echocardiogram (TTE) revealed mid-apical akinesis and ballooning (Figure 1A-B, Supplemental Video 1); a pattern commonly seen in Takotsubo cardiomyopathy (TC). The left ventricular ejection fraction was 40-45%. His initial ECG, demographics and profound biomarker elevation were atypical for TC, therefore he underwent cardiac magnetic resonance imaging (CMR) for diagnostic clarification (Figure 1d-e, Figure 2). The CMR findings were not in keeping with TC, but extensive acute myocarditis.Figure 2Cardiac Magnetic Resonance Images short axis (basal, mid and apical) segments. 2A-C. Images with late gadolinium enhancement (LGE) showing diffuse subepicardial and midmyocardial enhancement in basal to mid inferior, inferolateral, anterolateral and inferoseptal and transmural enhancement of the apical segments. D-F. T2 mapping showing increased T2 mapping value, representing inflammation, in the areas corresponding to regions of LGE. T2 relaxation time was increased at 62+/-14 ms. G-I. Extracellular volume (ECV) mapping showing increased ECV fraction (63% ± 25%) in the areas corresponding to LGE and T2. J-L. T1 mapping showing increased native T1 values in the areas corresponding to LGE. T1 relaxation time was increased at 1013 +/-88 ms. Polar maps are included for T2 mapping, ECV and T1 mapping adjacent to the corresponding row.View Large Image Figure ViewerDownload Hi-res image Download (PPT) Takotsubo cardiomyopathy is a reversible condition in which there is transient left ventricular (LV) dysfunction characterized most commonly by basal hyperkinesis and mid to apical LV ballooning and hypokinesis. The clinical presentation of TC is often similar to an acute coronary syndrome with chest pain, cardiac biomarker elevation and ECG changes. Typically, there is a preceding history of a physical or emotional stressor, including acute illness. Though TC is often suspected on LV gram or TTE, the Mayo diagnostic criteria recommends CMR to exclude alternate pathologies like myocarditis1Prasad A. Lerman A. Rihal C.S. Apical ballooning syndrome (Tako-Tsubo or stress cardiomyopathy): a mimic of acute myocardial infarction.Am Heart J. 2008; 155: 408-417Crossref PubMed Scopus (1275) Google Scholar. Two major advantages of CMR over other imaging modalities are myocardial edema detection and tissue characterization. The pattern of myocardial edema, seen as hyperintense T2 weighted signal or increase of native T1 signal or high extracellular volume (EVC), is typically transmural in TC, involving the areas of wall motion abnormality compared to the typical subepicardial or midmyocardial pattern in myocarditis2Haaf P. Garg P. Messroghli D.R. Broadbent D.A. Greenwood J.P. Plein S. Cardiac T1 Mapping and Extracellular Volume (ECV) in clinical practice: a comprehensive review.Journal of Cardiovascular Magnetic Resonance. 2016; 18: 89Crossref PubMed Scopus (0) Google Scholar. In our case, the T2 mapping, T1 mapping and ECV elevation in the mid segments were midmyocardial and epicardial, and transmural at the apex. The most striking differentiating factor in our case was the pattern and extent of late gadolinium enhancement (LGE), which often represents myocardial scar or fibrosis. Unlike in myocarditis, classic literature suggests there is an absence of LGE in TC3Fernández-Pérez G.C. Aguilar-Arjona J.A. de la Fuente G.T. Samartín M. Ghioldi A. Arias J.C. et al.Takotsubo cardiomyopathy: assessment with cardiac MRI.AJR Am J Roentgenol. 2010; 195: 139-145Crossref PubMed Scopus (0) Google Scholar, however focal or patchy LGE has been observed in a minority of cases, usually at a lower signal intensity than in acute myocarditis4Eitel I. von Knobelsdorff-Brenkenhoff F. Bernhardt P. Carbone I. Muellerleile K. Aldrovandi A. et al.Clinical Characteristics and Cardiovascular Magnetic Resonance Findings in Stress (Takotsubo) Cardiomyopathy.JAMA. 2011; ([Internet]) (Available from:): 306https://doi.org/10.1001/jama.2011.992Crossref Scopus (581) Google Scholar, due to the absence of scar formation in the transient TC2Haaf P. Garg P. Messroghli D.R. Broadbent D.A. Greenwood J.P. Plein S. Cardiac T1 Mapping and Extracellular Volume (ECV) in clinical practice: a comprehensive review.Journal of Cardiovascular Magnetic Resonance. 2016; 18: 89Crossref PubMed Scopus (0) Google Scholar. Our case illustrates the utility of CMR to distinguish acute myocarditis from TC. Due to the typical mid-to-apical wall motion abnormalities, the diagnosis may have been missed with LV gram and TTE alone. Once stabilized, he initiated guideline directed medical therapy for heart failure with reduced ejection fraction. His TTE approximately 1 month later showed persistence of the apical akinesis, further evidence against TC, which should have normalized. A CMR was repeated 6 weeks post presentation which demonstrated negative remodelling, extensive LGE, in the same locations, as a result of previous myocarditis without ongoing inflammation.Novel Teaching Points:•Acute myocarditis and takotsubo cardiomyopathy (TC) can present similarly.•CMR is a useful modality to differentiate acute myocarditis and TC, and its use is supported by guidelines5Ghadri J.R. Wittstein I.S. Prasad A. Sharkey S. Dote K. Akashi Y.J. et al.International Expert Consensus Document on Takotsubo Syndrome (Part I): Clinical Characteristics, Diagnostic Criteria, and Pathophysiology.Eur Heart J. 2018; 39: 2032-2046Crossref PubMed Scopus (613) Google Scholar. We suggest considering CMR in cases where clinical findings such as ECG, biomarkers, demographics, and clinical trajectory are atypical for TC.•Key differences on CMR include the pattern of edema being transmural in TC compared to subepicardial and mid wall in myocarditis and the extent of LGE, with TC having no to minimal LGE. None