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Abstract Background Dilated cardiomyopathy (DCM) is defined as the presence of left ventricular or biventricular dilatation and systolic dysfunction in the absence of abnormal loading conditions or significant coronary heart disease. The diagnostic work-up for patients with DCM includes cardiac imaging and cardiac magnetic resonance (CMR) is the gold-standard method for detailed morphological caracterization. Although there is a limited diagnostic role for radionuclide imaging in DCM, myocardial perfusion single-photon emission computed tomography (SPECT) is commonly performed to exclude ischemic etiology. Purpose The aim of this study was to compare the findings of myocardial perfusion SPECT (MPS) and CMR in non-ischemic DCM. Methods We included 35 patients that had been diagnosed with DCM and underwent MPS and CMR for etiological diagnosis in our institution between January 2020 and December 2023. We evaluated left ventricular motility, thickening and perfusion defects in MPS, the presence of late gadolinium enhancement (LGE) in CMR and the values of left ventricular ejection fraction (LVEF), end-systolic and end-diastolic volumes in both exams. Results 24 patients were male (69%), with a median age of 65,9 ± 11,8 years. Ischemic etiology for DCM was excluded based on CMR in 25 patients, 6 patients were diagnosed with alcoholic DCM, 3 patients with familial DCM and 1 with chemotherapy-induced cardiotoxicity. In 23 patients (66%), MPS showed diffuse motility and thickening abnormalities. In MPS, 34 patients (97%) had perfusion defects and 17 (50%) had reversible defects. 14 patients (41%) had only one perfusion defect while 20 (59%) patients had 2 or more. The septal wall was the most affected (24 patients - 69%). In 24 patients (69%), CMR showed LGE suggestive of fibrosis and in 88% of these patients the fibrosis was seen in the septal wall. A moderate correlation (0,508) was found between LVEF in MPS and CMR. 8 patients (33%) presented LGE in CMR and had non-reversible perfusion defects in the same myocardial wall in MPS while 12 patients (50%) presented with reversible perfusion defects in the same LGE location. Of the 12 patients that presented with LGE in CMR and reversible defects in MPS, 7 (58%) had total or parcial but significant reversibility and 5 (42%) had partial but non-significant reversibility. Conclusions The presence of perfusion defects is common in non-ischemic DCM. In most patients the perfusion defects (MPS) and fibrosis (CMR) were seen in the septal wall. Reversible defects may be explained by microvascular dysfunction known to play a role in DCM pathogenesis. These findings should be taken into account in the interpretation of MPS results in the etiological diagnosis of DCM.
Nunes et al. (Thu,) studied this question.