Presentation
History of viral infection. Admitted with acute coronary syndrome 10 days prior. Elevated high-sensitivity troponin and C-reactive protein. Obstructive CAD ruled out by coronary angiography. Pericardial effusion on TTE.
Patient Data
Heart rate: 68 bpm, haematocrit: 0.44
Image quality: mild respiratory artifacts, otherwise no limitations
Morphology and functional analysis (endo-volume):
LV-EDVI: 100 mL/m²
LV-ESVI: 42 mL/m²
LV-SVI: 59 mL/m²
LV-EF: 58%
cardiac output: 9.1 L/min
cardiac index: 3.9 L/min/m²
LV-ED wall mas index (without papillary muscles): 57 g/cm²
septum thickness: 9 mm
Findings:
no regional left ventricular wall motion abnormalities
visually normal atrial size
no significant cardiac valve pathology
no intracavitary thrombi
minimal pericardial enhancement adjacent to the left ventricular free wall
no pericardial effusion
minimal right pleural effusion
Myocardial tissue properties (according to Lake Louise criteria 2018)1:
Regional myocardial oedema is visible in the lateral wall from midventricular to apical.
Subepicardial and patchy intramyocardial late gadolinium enhancement (LGE) best visible in the lateral anterior and inferior segments of the left midventricular and apical myocardium
T1 mapping native: >1100 in the midventricular and apical lateral wall
extracellular volume (ECV): >31% in the midventricular and apical lateral wall
T2 mapping: 56-68 ms (z-score: ~2-6)
*normal reference ranges based on local data:
-
native T1: 940-1060 ms; ECV: >32%; T2: 44-56 ms
Impression:
Cardiac MRI findings are consistent with extensive acute inflammatory changes of the myocardium or acute myocarditis.
Exam courtesy: Kirsten Fleckstein & Jeanette Moses (radiographer)
Case Discussion
MR imaging findings of severe myocardial inflammation in a young patient admitted with acute coronary syndrome 10 days earlier.
Both main criteria of the updated new Lake Louise criteria are fulfilled in this case 1:
myocardial oedema (on T2w images and T2 mapping)
non-ischaemic myocardial injury (abnormal native T1, ECV and LGE)
Apart from minimal pericardial enhancement, there are no supportive criteria (pericarditis, systolic dysfunction) present.
In view of the clinical presentation and diagnostic criteria from different categories and the absence of coronary artery disease and any known cardiovascular disease or extracardiac aetiologies that could explain the condition, the diagnosis of myocarditis can be confidently made 2,3.
A follow-up MRI was recommended due to the extent of the myocardial injury visible on late gadolinium enhancement and the involvement of the interventricular septum the latter being associated with a less favourable prognosis 4.
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