Myocardial injury aggravated by hypothyroidism in patients with idiopathic dilated cardiomyopathy: the evidence based on 99Tcm-MIBI SPECT/18F-FDG PET imaging and cardiac MRI / 中华核医学与分子影像杂志

ABSTRACT

Objective To explore the relationship between hypothyroidism and myocardial injury in patients with idiopathic dilated cardiomyopathy (IDC) by 99Tcm-MIBI SPECT/18 F-FDG PET and late-gadolinium enhancement cardiac magnetic resonance imaging (cMRI-LGE).Methods Sixty-three consecutive patients (42 males and 21 females,(52±11) years) with IDC were enrolled from October 2010 to December 2012.Serum TT3,TT4,FT3,FT4 and TSH were determined using a fully automated chemiluminescence immunoassay.All patients underwent 99Tcm-MIBI myocardial perfusion SPECT/18F-FDG myocardial metabolism PET imaging and cMRI-LGE.Seventeen segments model was used for segmental analysis.Patterns of perfusion/metabolism were classified as normal,mismatch,mild-to-moderate match and complete match.cMRI-LGE was classified into 3 categories (non-LGE,mid-wall LGE and transmural LGE).x2 test was used for data analysis.Results All patients were divided into euthyroid group (n =53) and hypothyroidism group (n =10) according to the levels of serum thyroid hormones.The percentage of normal perfusion/metabolism segments in the euthyroid group was apparently higher than that in the hypothyroidism group71.8％ (647/901) vs 57.6％ (98/170),x2 =13.50,P＜0.001 ; whereas the percentage of perfusion/metabolism mismatch segments in the euthyroid group was significantly lower than that in the hypothyroidism group17.8％ (160/901) vs 31.2％ (53/170),x2=16.20,P＜0.001.The euthyroid group had a higher percentage of non-LGE segments (88.0％ (793/901) vs 69.4％ (118/170),x2 =35.70,P＜0.001) and a lower percentage of mid-wall LGE segments (4.8 ％ (43/901) vs 24.1％ (41 / 170),x2 =74.70,P＜ 0.001) compared to hypothyroidism group.Conclusions Hypothyroidism has a detrimental effect on myocardium.99Tcm-MIBI SPECT/18F-FDG PET imaging is sensitive in detecting viable/ischemia myocardium,and cMRI-LGE is good at detecting moderate fibrosis.Combining SPECT/PET imaging and cMRI-LGE for assessing myocardial injury would provide more comprehensive information.