Liu Chunhua, Lv Haihong, Li Qian, Fu Songbo, Tan Jiaojiao, Wang Chenyi, Wang Xiaoqian, Ma Yuping
Department of Endocrinology, The First Hospital of Lanzhou University, Lanzhou, Gansu, P.R. China.
Medicine (Baltimore). 2020 Jul 10;99(28):e21190. doi: 10.1097/MD.0000000000021190.
The effects of thyrotropin (TSH) suppressive therapy on autonomic regulation and ventricular repolarization in patients with differentiated thyroid cancer (DTC) have not been elucidated. The aim of present study was to evaluate variation in heart rate variability (HRV) and QT dispersion after TSH suppressive therapy in patients with DTC.Cases, defined as 271 patients with DTC within 1 year of exogenous levothyroxine, and all patients underwent a full history, physical examination, including standard 12 lead electrocardiogram (ECG), and 24 h ambulatory ECG monitoring (Holter) with normal free thyroxine (FT4) and free triiodothyronine (FT3) with levothyroxine. To evaluate effects of TSH suppressive therapy on HRV and QT dispersion, patients were divided into three groups according to different levels of TSH: TSH < 0.1 mIU/L group and 0.1 ≤ TSH < 0.5 mIU/L group were as TSH suppression groups, and 0.5 ≤ TSH < 2.0 mIU/L group was as TSH replacement group.Comparing with 0.5 ≤ TSH < 2.0 mIU/L group, significant changes in both time and frequency domain of HRV and QT dispersion were observed in TSH < 0.1 mIU/L group (P < .001: SDNN, SDANN, HF, LF/HF, QTd, and QTcd; P < .05: rMSSD) and 0.1 ≤ TSH < 0.5 mIU/L group (P < .001: SDNN, HF, LF/HF, QTd, and QTcd), and especially were more pronounced in TSH < 0.1 mIU/L group. Moreover, we found that TSH level was proportional to SDNN (β = 15.829, P < .001), but inversely proportional to LF/HF (β = -0.671, P < .001), QTd (β = -16.674, P < .001) and QTcd (β = -18.314, P < .001) in DTC patients with exogenous levothyroxine.Compared with euthyroid state, patients with suppressed serum TSH have increased sympathetic activity in the presence of diminished vagal tone, ultimately showed sympathovagal imbalance and with an increased inhomogeneity of ventricular recovery times. These findings revealed that TSH suppression therapy had a significant impact on cardiovascular system and had certain guiding role in the treatment and management of patients with DTC.
促甲状腺素（TSH）抑制疗法对分化型甲状腺癌（DTC）患者自主神经调节和心室复极的影响尚未阐明。本研究旨在评估DTC患者接受TSH抑制治疗后心率变异性（HRV）和QT离散度的变化。
病例为271例在接受外源性左甲状腺素治疗1年内的DTC患者，所有患者均接受了全面的病史、体格检查，包括标准12导联心电图（ECG），以及24小时动态心电图监测（Holter），且游离甲状腺素（FT4）和游离三碘甲状腺原氨酸（FT3）水平正常并接受左甲状腺素治疗。为评估TSH抑制疗法对HRV和QT离散度的影响，根据TSH不同水平将患者分为三组：TSH＜0.1 mIU/L组和0.1≤TSH＜0.5 mIU/L组为TSH抑制组，0.5≤TSH＜2.0 mIU/L组为TSH替代组。
与0.5≤TSH＜2.0 mIU/L组相比，TSH＜0.1 mIU/L组（P＜0.001：SDNN、SDANN、HF、LF/HF、QTd和QTcd；P＜0.05：rMSSD）和0.1≤TSH＜0.5 mIU/L组（P＜0.001：SDNN、HF、LF/HF、QTd和QTcd）的HRV和QT离散度在时域和频域均有显著变化，尤其在TSH＜0.1 mIU/L组更为明显。此外，我们发现外源性左甲状腺素治疗的DTC患者中，TSH水平与SDNN呈正相关（β = 15.829，P＜0.001），但与LF/HF（β = -0.671，P＜0.001）、QTd（β = -16.674，P＜0.001）和QTcd（β = -18.314，P＜0.001）呈负相关。
与甲状腺功能正常状态相比，血清TSH受抑制的患者在迷走神经张力降低的情况下交感神经活动增加，最终表现为交感-迷走失衡以及心室恢复时间的不均一性增加。这些发现表明，TSH抑制疗法对心血管系统有显著影响，对DTC患者的治疗和管理具有一定的指导作用。
