Delayed-enhancement is not always myocardial infarct scar

Description of Clinical Presentation: A 43-year-old man with no medical history was admitted due to worsening functional class (NYHA II) for 4 weeks. Physical examination revealed bradycardia (HR 40 bpm), BP 146/88 mmHg, and no other abnormalities. ECG: third-degree atrioventricular block. Imaging tests were requested.

Diagnostic Techniques and Their Most Important Findings: Cardiac magnetic resonance (CMR) performed with and without contrast on a 1,5T (Siemens Healthineers, MAGNETOM Sola). Steady state free precession images (SSFP) localizer as well as cine images were performed. Edema-weighted STIR, pre contrast T1 and T2 mapping, myocardial first pass perfusion images were acquired followed by injection of gadolinium, and late-enhancement images were acquired 10 min after contrast injection.

CMR examination revealed normal LV and RV size with normal systolic function (quantitative LVEF: 68%, RVEF: 63%). Tissue characterization demonstrated hyperintensity on T2-weighted STIR images in the myocardium related to edema in the same areas with late gadolinium enhancement. Parametric T1 mapping was normal and T2 mapping was increased (55ms). Myocardial perfusion images were normal . The presence of multifocal LGE with non-ischemic pattern (Figure 1), affecting the mesocardium / subepicardium in the middle and basal segments of the left ventricle.

Given the possibility of infiltrative cardiomyopathy based on the findings described, FDG-PET was requested, revealing areas of abnormal cellular metabolic activity in the cervicothoracic, mediastinal, bilateral hilar, and right iliac bifurcation lymph nodes, as well as in the myocardium (Figure 2).

Once the diagnosis of sarcoidosis – Stage I was made, clinical treatment was initiated and a definitive pacemaker was placed.

Learning Points from this Case: Cardiac sarcoidosis (CS) is an infiltrative cardiomyopathy characterized by granulomatous inflammation of the myocardium. Systemic sarcoidosis can affect any organ in the body. While pulmonary involvement is common, CS specifically carries substantial risks including high-grade conduction disease, ventricular arrhythmias, heart failure, and sudden cardiac death. CS can be the first or even the sole manifestation of sarcoidosis, which may indicate a more severe disease.

This case emphasizes the role of CMR is a fundamental, non-invasive, high-spatial-resolution imaging technique widely used for the diagnosis, risk stratification, and evaluation of CS. It provides precise assessment of cardiac structure and function, including biventricular size and function, and is highly sensitive for detecting myocardial fibrosis and edema.

Figure 1: Hyperintensity on T2-weighted STIR images in the myocardium related to edema and late gadolinium enhancement affecting the mesocardium / subepicardium in the middle and basal segments of the left ventricle.
Figure 2: FDG-PET revealed areas of abnormal cellular metabolic activity in the cervicothoracic, mediastinal, bilateral hilar, and right iliac bifurcation lymph nodes, as well as in the myocardium.