RESUMO
AIM: To estimate the capabilities of 99mTc-pyrphotech single-photon emission computed tomography (SPECT) in the diagnosis of myocardial inflammatory changes in patients with persistent atrial fibrillation (AF). SUBJECTS AND METHODS: Nineteen patients (11 males and 8 females, mean age 47.46 ± 9.92 years) with persistent idiopathic AF underwent preoperative complete clinical and instrumental examination. 99mTc-pyrphotech SPECT was performed to identify foci of myocardial inflammatory changes. After completing 99mTC-pyrphotech scanning, resting myocardial perfusion scintigraphy with 99mTC-methoxyisobutylisonitrile (99mTc-MIBI) was performed in accordance with the standard protocol. The scintigrams obtained in both studies were then combined using the applied programs Jet Stream Workspace Release 2.5 (Philips) and the application Fusion. During invasive intervention, endomyocardial samples were intraoperatively taken from all the patients for histological and immunohistochemical examinations. RESULTS: Abnormal 99mTc-pyrphotech myocardial accumulation was found in 7 (36.8%) of the examinees, multiple foci in 3 cases and single foci in 4. Analysis of perfusion scintigrams indicated that the mean abnormal accumulation of 99mTc-MIBI in the left ventricle was 3.75 ± 0.88% (maximum 9%). Histological examination of endomyocardial samples from 19 patients with persistent AF verified myocarditis in 4 (21%) patients and myocardial sclerosis concurrent with other abnormalities in 15 (78.9%) patients. CONCLUSION: Latent lymphocytic or polymorphic cellular myocarditis of viral etiology is a cause of idiopathic AF in 20% of the cases. 99mTc-pyrphotech scintigraphy may be one of the primary noninvasive diagnostic techniques for the detection of myocardial inflammation in this form of arrhythmia.
