The Effect Of Subclinical Hypothyroidism On The Prognosis Of Patients With Non-ST-Segment Elevation Myocardial Infarction

Objectives To investigate the effect of subclinical hypothyroidism(SH)on the prognosis of non-ST-segment elevation myocardial infarction(NSTEMI).Further explore the effects of thyroid stimulating hormone(TSH),total triiodothyronine(TT3),total thyroxine(TT4)on the prognosis of NSTEMI.Methods 370 Patients with NSTEMI who were treated in Hebei general hospital from January 2016 to August 2018 were collected.A total of 105 patients were excluded due to lack of data,application of thyroid hormones,thyroid metabolic diseases,loss of follow-up and non-SH dysfunction.According to the patient's thyroid hormone(TH)level,subjects were divided into two groups: euthyroid(EU)and SH group: 1 EU group: TSH and TT4 levels were within the reference range,n=237.2 SH group: TSH>4.2 m IU/L,TT4 is within the normal range,n=28.Followed up for 24.6(18.9,31.6)months.Baseline data,echocardiographic indicators,in-hospital arrhythmia events,in-hospital end-point events,major adverse cardiovascular events(MACE)and minor adverse cardiovascular events were collected and compared between the two groups.Results 1 Comparison of baseline data: Compared with the EU group,the TSH level in the SH group was higher(P<0.001),the use of nitrate esters during hospitalization was lower(73% to 50%,P=0.012),and aspartate transferase(P=0.022),creatine kinase(P=0.004),and red blood cell count(P=0.030)were lower,the remaining baseline data were not significantly different.2 Comparison of echocardiographic indexes:Compared with the EU group,the diameter of the left ventricular systole in the SH group was reduced(P=0.020),and the remaining echocardiographic indicators were not significantly different.3 Comparison of arrhythmia events in the hospital:After multivariate logistic regression analysis,the risk of arrhythmia events such as sinus bradycardia(OR 9.564,95%CI1.634-55.989,P=0.012),atrial flutter(OR 7.824,95%CI 1.652-37.055,P=0.010),pre-phase contraction of the atrioventricular junction(OR 4.940,95%CI 1.468-16.625,P=0.010)occurred in the SH group is still high.4 Comparison of in-hospital endpoint events [hospital death and heart failure(HF)]: There was no significant difference between the two groups.5 Comparison of MACE events(all-cause death,cardiac death,nonfatal recurrent myocardial infarction,revascularization,malignant arrhythmia): Kaplan-Meier survival curve analysis showed that compared with the EU group,the survival rate without MACE events was lower in the SH group,but there was no statistically significant difference(Log-rank P=0.222).Divided into four groups according to TSH levels,theresults showed that compared with TSH 1.59-2.89 m IU/L group,TSH 2.90-4.20 m IU/L group and TSH>4.20 m IU/L group increased the risk of MACE events(Log-rank P values are P=0.022,P=0.041,respectively).Cox univariate analysis showed that TT3 ?1.75ng/m L was associated with increased risk of MACE events(P=0.007).After factor P<0.05 was included in the multivariate Cox regression,the incidence of MACE events at TT4 104.34-142.63 ug/ml was low(HR 0.440,P=0.046).6 Comparison of all-cause death:The multivariate cox proportional hazard regression model showed that as the level of TT3 increased,the risk of all-cause death decreased(HR 0.362,95% CI 0.136-0.964,P=0.042).7 Comparison of minor adverse cardiovascular events(HF,repeat coronary angiography,bleeding,stroke,cardiogenic readmission)and cardiogenic readmission: Cox analysis also showed that SH and upper tertiles of TSH in the normal range(TSH 1.59-2.89 m IU/L P=0.019,TSH 2.90-4.20 m IU/L P=0.030,TSH> 4.20 m IU/L P=0.011)increased the risk of minor adverse cardiovascular events.The SH group(TSH>4.20 m IU/L)(HR 2.911,95% CI 1.422-5.962,P=0.003),the middle and upper tertiles TSH levels were also related to increased cardiogenic readmission risk(TSH 1.59-2.89 m IU/L P=0.007,TSH 2.90-4.20 m IU/L P=0.013).Conclusions In the SH group,there was a downward trend in the survival rate without MACE events,and there was an increased risk of minor adverse cardiovascular events and cardiogenic readmissions.The risk of arrhythmias such as sinus bradycardia,atrial flutter,and pre-phase contraction of the atrioventricular junction increased in the SH group.Even if thyroid function is within the normal reference range,an increase in TSH levels are associated with decreased survival rates without MACE events and increased risk of minor adverse cardiovascular events and cardiogenic readmission rates,whereas the TT4 level in the middle tertile of the normal range is a protective factor for MACE events.In general,it is necessary to identify the presence of SH in advance and monitor the thyroid function of patients with NSTEMI,which helps to identify and manage high-risk patients in advance,thereby benefiting more patients.Figure [2];Table [10];Reference [196].