PMC10401478_01
Non-sustained ventricular tachycardia in the continuous electrocardiographic monitoring report. Selected four electrocardiographic (ECG) strips at 25 mm/s, each showing three leads, as a part of the 6-lead ECG holter recorder DMS 300-4l 24 h report (DM Systems Co., Ltd., Beijing, China) after visualization with Holter Analyzer Software version 4.0076 (DM Systems Co., Ltd., Beijing, China).
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The 24 h continuous electrocardiographic monitoring (cECG) revealed non-sustained ventricular tachycardia (Figure 1). The cECG showed ventricular heterotopy of 310 solitary and 80 pairs of ventricular extrasystoles, as well as 114 paroxysms of NSVT with a heart rate of up to 200 bpm and a duration of up to 20 s (Figure 1, Supplementary Table S1). In the late gadolinium enhancement (LGE) sequences with phase-sensitive inversion recovery (PSIR), there were an LGE midwall striae in the basal and midseptums (Supplementary Figure S1). The left ventricular ejection fraction was mildly reduced (LVEF 46%), but the mid-ventricular imbibition of the interventricular septum and its insertion in segment 9 in late post-contrast sequences was minimal then (Supplementary Figure S1). Based on new terminology, the patient most likely has dilated cardiomyopathy with excessive trabeculation of the myocardium, according to increased volume of both ventricles and decreased systolic function of the left ventricle with signs of myocardial fibrosis typical for dilated cardiomyopathy (Supplementary Figure S1). The difference in LGE observed between the two CMR imaging time points may suggest disease progression of dilated cardiomyopathy with excessive trabeculation (Supplementary Figure S1) but does not fully explain the observed cECG report.
Cine cardiac magnetic resonance images of left ventricular cardiomyopathy with excessive trabeculation. Representative images of cine cardiac magnetic resonance imaging (CMR) steady-state free precession (SSFP) sequences at the time of diagnosis of cardiomyopathy with excessive trabeculation (left panel) and the onset of amiodarone-induced thyroiditis (right panel). The first row of images represents the four-chamber view through the horizontal long axis, whereas the second row consists of the short-axis pre-contrast scan (left panel) and vertical long-axis scan (right panel). Magnetic Resonance Imaging Scanner Siemens Magnetom  Avanto 1.5T (Siemens Medical Solutions, Inc., Hoffman Estates, IL, USA) was used to acquire CMR scans.
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Cine cardiac magnetic resonance (CMR) steady-state free precession sequences showed a dilated left ventricle with septum hypo-dyskinesia and an ejection fraction of 48%, as well as excessive trabeculation in segments 13, 15, and 16, and a part of segments 7 and 10 with a non-compact to compact myocardium (NC/C) ratio higher than 2.3 in end-diastole (Figure 2). Differential diagnosis also included status post myocarditis, but pathognomonic imaging signs of acute myocarditis were not detected at relevant time points (Supplementary Figure S2).
99mTc-sestamibi thyroid scintigraphy confirming the diagnosis of type II amiodarone-induced thyroiditis. Neck and thorax scintigraphy was recorded in the anterior projection at 10 (on the left) and 60 min (on the right) after intravenous administration of 375 MBq of 99mTc-sestamibi. Radiopharmaceutical 99mTc-sestamibi was prepared using a commercially available kit Stamicis  (Curium, Gif-sur-Yvette Cedex, France) and freshly eluted 99mTc pertechnetate (375 MBq; Mallinckrodt, Petten, Netherlands). Symbia T2 dual-head hybrid gamma-camera equipped with multipurpose low-energy high-resolution collimators (Siemens Medical Solutions, Inc., Hoffman Estates, IL, USA) was used for recording.
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Moreover, scintigraphic imaging after intravenous injection of 375 MBq 99mTc-sestamibi showed decreased thyroid uptake (Figure 3).
Dynamics of free thyroid hormone concentrations before, during, and after immunomodulatory treatment of amiodarone-induced thyroiditis. Data are presented as individual values of free thyroxine (FT4) and triiodothyronine (FT3) concentrations before, during, and after prednisone treatment. The treatment duration is marked as a grey background area ranging from day 1 to day 15. Reference intervals for FT4 and FT3 levels are indicated by blue and purple transparent areas, respectively. Serum concentrations of FT4 and FT3 were determined by electrochemiluminescence immunoassay (ECLIA) using commercially available assays Elecsys FT3 III (Roche Diagnostics GmBH, Manheim, Germany) and Elecsys FT4 IV (Roche Diagnostics GmBH, Manheim, Germany) on the Cobas  8000 analyzer series cobas  e 801 analytical unit (Roche Diagnostics International, Ltd, Rotkreuz, Switzerland).
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After only a week of corticosteroid treatment, TSH was 0.01 mIU/L and free thyroxine level dropped to 26 pmol/L (Figure 4). After 2 weeks, the target levels of thyroid hormones were reached, and prednisone treatment was gradually de-escalated until complete discontinuation (Figure 4).