Thyroid-stimulating hormone within the normal range and risk of major adverse cardiovascular events in non-ischemic dilated cardiomyopathy patients with severe left ventricular dysfunction.

Background The association between thyroid-stimulating-hormone (TSH) and prognosis of nonischemic dilated cardiomyopathy (NIDCM) in patients with normal thyroid function remains unclear. Hypothesis Our aim was to investigate the association between TSH and major adverse cardiovascular events in euthyroid NIDCM patients. Methods The original cohort consisted of 216 consecutive euthyroid NIDCM patients, with left ventricular ejection fraction (LVEF) <= 35%, who were observed from 2010 to 2013. Patients with persistent ventricular arrhythmia (VA) histories, amiodarone taken for VA prevention, or on heart transplant list within 1 year were excluded. A follow-up evaluation was performed, and VA events, heart failure (HF) exacerbation/heart transplant, cardiac death, or death from any cause were separately evaluated. Results A total of 184 patients were enrolled, and 97.8% (180/184) ultimately received follow-up evaluations. During the median 4.6-year follow-up, 24 VA events, 28 cardiac deaths, 30 all-cause deaths, 40 HF exacerbations, and 11 heart transplant events occurred. Serum TSH levels showed good predictive efficacies for VA events (area under the curve [AUC] = 0.702, 95% confidence interval [CI]: 0.629-0.767), and the risk of VA events increased, according to serum TSH quarters, as determined by Kaplan-Meier analysis (2.2% vs 13.4% vs 21.0% vs 30.0%, Q1-Q4, P = 0.011). Multivariable Cox analysis showed that patients at the Q4 level of serum TSH (>2.67 mIU/L) suffered an increased risk of VA events, compared with those at the Q1 level of TSH (hazard ratio [HR] = 15.88, 95% CI: 2.01-65.15) or those at the other three quarters (HR = 3.17, 95% CI: 1.38-7.26). However, the Q4 TSH level was not associated with other adverse cardiac events. Conclusion An association between TSH levels and the risk of VA events may exist in euthyroid NIDCM patients.