Relationship of low FT3 levels and prognosis in patients with acute coronary syndrome

Abstract

Objective To evaluate the association between free triiodothyronine(FT3)levels and the prognosis of patients with acute coronary syndrome(ACS). Methods A total of 489 ACS patients who were admitted into our hospital during 2012 to 2014 were included to measure serum thyroid hormone levels.Patients were divided into normal FT3 group and low FT3 group according to FT3 levels.All patients underwent a follow-up for one year to compare the mortality and major adverse cardiac events(MACE)between the two groups. Results Patients with low FT3 had higher level of total cholesterol, apolipoprotein E, fasting plasma glucose serum and creatinine than normal FT3 group [(6.79±3.17)mmol/L vs.(4.57±2.92)mmol/L, P<0.01; (4.53±1.47)mmol/L vs.(4.03±1.06)mmol/L, P<0.01; (6.64±3.82)mmol/L vs.(5.88±2.24)mmol/L, P<0.01; (116.64±43.20)μmol/L vs.(97.99±30.85)μmol/L, P<0.01], while they also had a lower level of HDL cholesterol [(0.98±0.17)mmol/L vs.(1.03±0.26)mmol/L, P=0.04]. Meanwhile, low FT3 group had a lower level of left ventricular ejection fraction(54.74%±10.03% vs. 58.71%±7.96%, P<0.01), a higher level of NT-proBNP [739(304, 4 922)pg/ml vs. 140(62, 462)pg/ml, P<0.01] and a higher proportion of three-vessel disease than normal FT3 group(73.3% vs. 43.8%, P<0.01). During 1 year follow-up, the mortality(13.1% vs. 5.9%, P=0.03)and the rates of revascularization(15.4% vs. 7.6%, P=0.02)and MACE(27.4% vs. 14.0%, P<0.01)were higher in low FT3 patients.Kaplan-Meier analysis showed that cumulative survival freedom from MACE was significantly reduced in low FT3 patients(72.6% vs. 86%, log rank P <0.01). Multivariable Cox proportional hazards model revealed the low FT3 level was an independent predictor of MACE(HR=0.010, P=0.01). Conclusions The low serum FT3 is prevalent in ACS patients, and ACS patients with low FT3 are more likely to have a poorer prognosis. Key words: Acute coronary syndrome; Thyroid function; Triiodothyronine; Prognosis