Effects Of Thyroid Function On Myocardial Damage And Long - Term Prognosis In Patients With Cardiovascular Disease

The free triiodothyronine level correlates with the degree of myocardial injury and long-term prognosis in patients with acute myocardial infarctionBackground:Previous studies have suggested that hypothyroidism correlated with coronary heart diseases (CHD) mortality in long-term cohort, but whether the thyroid function status is associated with myocardial injury in acute myocardial infarction (AM) has not been investigated sufficiently.Methods:One thousand one hundred and twelve hospitalized patients from January 2010 to December 2011, with the diagnosis of AM, were enrolled in this study. All patients underwent testing for thyroid function status, cTnI, cardiac enzymes, C-reactive protein (CRP). We investigated the association between thyroid hormone levels and cardiac markers (creatine kinase-MB and cTnI), and thus evaluated the potential role of thyroid function status in predicting the myocardial injury. The risk of mortality was evaluated based on fT3 and TSH, respectively.Results:There were 222 patients (20.0%) who had thyroid dysfucntion including low-T3-syndrome (90 patients,8.1%), subclinical hyperthyroidism (73 patients,6.6%), subclinical hypothyroidism (51 patients,4.6%) and clinical hypothyroidism (8 patients, 0.7%) and. After adjusting for conventional risk factors (age, gender, smoking, diabetes mellitus, dyslipidemia, hypertension), free triiodothyronine (FT3) was significantly and negatively correlated with log-CKMB (r=-0.251, P<0.001) and log-cTnI (r=-0.287, P<0.001), indicating that the lower thyroid hormone level correlates with the severer cardiac injury in STEMI patients. FT3 also had a moderate negative correlation with CRP (r=-0.469, P<0.001), which might indicate that hypothyroidism may activate the inflammation response. No significant correlation was found between other thyroid parameters (TSH, FT4) and cardiac markers. In patients with moderate-and high-dosage statin therapy, FT3 is negatively related with the levels of total cholesterol (moderate dosage:Liner Coeff=-0.105, P=0.031; high dosage:Liner Coeff=-0.172, P=0.029) and LDL-c (moderate dosage:Liner Coeff=-0.082, P=0.001; high dosage:Liner Coeff=-0.113, P=0.005). In patients with low-dosage statin therapy, no correlation was found. In two-year follow-up, low FT3 groups (<1.79 group and 1.80-2.42 group) were the independent risk factors for MACE (HR:3.37,95%CI:1.66-6.85; HR:2.28,95%CI: 1.23-4.20). In addition, patients with elevated TSH level suffered high risk for MACE, while suppressed TSH group did not show significant impact (HR:1.545,95%CI: 0.91-2.61).Conclusions:As the lower FT3 level correlates with higher level of cardiac markers and lower LVEF, the hypothyroidism may be a predictor for myocardial injury in AMI. In AMI patients with moderate or high dosage statin therapy, FT3 is negatively related with cholesterol levels. Both low FT3 and high TSH are the risk factors of MACE in AMI. These results may warrant further study to investigate whether reversing the hypothyroidism could benefit the AMI patients.Thyroid Status, Cardiac Function and Mortality in Patients with Idiopathic Dilated CardiomyopathyBackground:Previous studies claiming a relationship between thyroid dysfunction and poor prognosis of heart failure (HF) had a major limitation in that they included patients with different etiologies. With complete information of thyroid function profile from four hundred and fifty eight consecutive patients with idiopathic dilated cardiomyopathy, we tested the hypothesis that thyroid status can independently influence mortality in patients with HF.Methods:The original cohort consisted of 572 consecutive patients with idiopathic dilated cardiomyopathy (IDCM) and 458 patients remained at the end of follow-up. All patients took thyroid function tests and other regular examinations in hospital. The risk of mortality was evaluated based on fT3, TSH, and the whole thyroid function profile, respectively.Results:The most frequent thyroid dysfunction was subclinical hypothyroidism (n=41), followed by subclinical hyperthyroidism (n=35,9%), low-T3 syndrome (n=17,74%), and hypothyroidism (n=12,3%). Compared with NYHA Ⅰ-Ⅱ group, patients with NYHA III-IVhad significantly lower FT3 (2.89±0.45 vs 2.68±0.54, P=0.05) and higher log-TSH (2.18±0.36 vs 2.30±0.45, P=0.02). No difference was found with respect of FT4 level. Logistic analysis showed both log-TSH (OR:2.189,95%CI:1.217-3.938) and FT3 (OR:0.483,95%CI:0.301-0.775) were independent predictors of exacerbated cardiac function (NYHA Ⅲ-Ⅳ vs NYHA Ⅰ-Ⅱ). During the follow-up (17±8 months),111 cumulative deaths occurred. In analysis based on FT3 level, low FT3 was a strong predictor of mortality (HR 3.18,95%CI:1.96-5.16). In analysi based on TSH level, elevated TSH showd independent predicting value for all-cause mortality (HR:2.828, 95%CI:1.902-4.206), while suppressed TSH had no impact (HR:0.883,95%CI: 0.426-1.827). In analysis based on the whole thyroid profile, hypothyroidism was the strongest predictor of mortality (hazard ratio (HR),4.189; 95%CI,2.118-8.283), followed by low-T3 syndrome (HR,3.147; 95%CI,1.558-6.355) and subclinical hypothyroidism (HR,2.869; 95%CI,1.817-4.532). Subclinical hyperthyroidism showed no significant impact.Conclusions:We found clear association between thyroid dysfunction and increased risk of mortality in IDCM with HF. These results suggest that monitoring thyroid function in HF patients is necessary, and further studies on treatment of HF with thyroid dysfunction is needed.Free Triiodothyronine Level Correlates with Myocardial Injury and Prognosis in Idiopathic Dilated Cardiomyopathy:Evidence from Cardiac MRI and SPECT/PET ImagingBackground:Previous studies have showed that thyroid hormone levels correlate with cardiac function and thyroid dysfunction is associated with poor prognosis in heart failure. But theories of mechanisms are mainly based on animal experiments but not on human level. Clinically, myocardial fibrosis could be detected by cardiac magnetic resonance imaging (MRI). Myocardial perfusion and metabolism could be evaluated by single-photon emission computed tomography (SPECT) and positron emission tomography (PET), respectively. In the present study, we aimed to explore the relation between thyroid hormone levels and myocardial injuries in idiopathic dilated cardiomyopathy (IDCM) using cardiac MRI and SPECT/PET imaging.Methods:Seventy-one consecutive patients diagnosed with IDCM were enrolled prospectively. Myocardial fibrosis was detected by late gadolinium enhancement (LGE) MRI, and myocardial perfusion/metabolism was evaluated by 99mTc-MIBI SPECT /18F-FDG PET imaging. Presence of different types of myocardial injuries were compared according to levels of thyroid hormone. An identical 17-segment model was used to divide the LV into six basal, six mid-ventricular, four distal segments, and the apex. Areas of LGE were classified into three categories:non-LGE, mid-wall LGE and transmural LGE. Segmental 99mTc-MIBI and 18F-FDG uptake were divided into four groups with different patterns of perfusion/metabolism:normal perfusion/metabolism, perfusion/metabolism mismatch, mild-to-moderate perfusion/metabolism match, and severe perfusion/metabolism match. Endpoints of the study were cardiac death and all-cause death.Results:From quartile 1 to 4, significant decreasing trend could be detected with respect to the percentage of segments with LGE (23.53%,16.54%,5.22%,3.11%, respectively; P<0.001) and perfusion abnormalities (20.88%,16.54%,14.05%,9.69%, respectively; P<0.001). As for segments with metabolic abnormalities, the lowest percentage was detected in the quartile 3 group, while those in quartile 1 and 2 were still much higher than quartile 3 (8.82%,7.35% vs 1.63%; P=0.032). Segments of normal perfusion/metabolism pattern were more frequent in higher FT3 level groups, with total percentage of perfusion/metabolism abnormalities lower in these groups. However, no significant trend could be found if we compared the mismatch, mild-moderate match and severe match separately. As for FT4 and TSH levels, no significant distribution trend of myocardial injuries could be detected. In logistic analysis, FT3 was independently associated with the presence of LGE (OR:0.140,95%CI:0.035 - 0.567), perfusion abnormalities (OR:0.172,95%CI:0.040 - 0.738) and metabolism abnormalities (OR: 0.281,95%CI:0.081 - 0.971). After a median follow-up of 46 months, LGE-positive and FT3<2.77 pg/mL was identified as the strongest predictor of cardiac events (HR:8.623, 95%CI:3.626-16.438).Conclusions:Low FT3 level is associated with myocardial fibrosis and perfusion/metabolism abnormalities in patients with IDCM. The combination of FT3 level and LGE provides useful information for assessing the prognosis of IDCM.