Department of Endocrinology and Metabolism and the Institute of Endocrinology, National Health Commission Key Laboratory of Diagnosis and Treatment of Thyroid Diseases, The First Hospital of China Medical University, Shenyang 110001, P. R. China.
J Clin Endocrinol Metab. 2022 Aug 18;107(9):2674-2683. doi: 10.1210/clinem/dgac417.
The impact of abnormal thyroid hormone levels on the cardiovascular system has been explored for decades. Recent emerging evidence suggests that subclinical thyroid dysfunction, especially subclinical hypothyroidism (SCH), significantly affects cardiac indices.
We aimed to determine whether levothyroxine (LT4), commonly used to treat hypothyroidism, affects cardiovascular indices in SCH patients.
This is a systematic review and meta-analysis. We searched online databases for studies analyzing cardiac morphology and functional changes in SCH patients before and after LT4 supplementation. A total of 294 SCH patients participated and finished the follow-up. The standard mean difference and 95% CI were calculated in fixed or random-effects models. The clinical outcomes analyzed in this study included 18 indicators, mainly covering cardiac morphology, myocardial performance (including various indicators of systolic and diastolic function), mitral wave flow, and systemic vascular resistance.
A total of 11 studies met our search criteria. All studies explicitly mentioned that serum thyrotropin levels decreased to normal at follow-up. Our results suggest that the cardiac output (CO), left ventricular ejection fraction (LVEF), and the ratio of peak E velocity/peak A velocity were all significantly increased after LT4 supplementation compared with the baseline level. However, we found no clear evidence of significant morphological changes in the heart.
Judging from the obvious changes in the CO, LVEF, and E/A ratio, LT4 supplementation can effectively improve the cardiac systolic and diastolic dysfunction prevalent in SCH patients. This study provides evidence of the recommendation for LT4 supplementation in adult SCH patients.
几十年来，人们一直在探索甲状腺激素水平异常对心血管系统的影响。最近新出现的证据表明，亚临床甲状腺功能障碍，特别是亚临床甲状腺功能减退症（SCH），会显著影响心脏指数。
我们旨在确定左甲状腺素（LT4），一种常用于治疗甲状腺功能减退症的药物，是否会影响 SCH 患者的心血管指数。
这是一项系统评价和荟萃分析。我们在网上数据库中搜索了分析 SCH 患者在 LT4 补充前后心脏形态和功能变化的研究。共有 294 名 SCH 患者参与并完成了随访。采用固定或随机效应模型计算标准均数差和 95%置信区间。本研究分析的临床结局包括 18 个指标，主要涵盖心脏形态、心肌性能（包括收缩和舒张功能的各种指标）、二尖瓣波流和全身血管阻力。
共有 11 项研究符合我们的检索标准。所有研究都明确提到，随访时血清促甲状腺激素水平降至正常。我们的结果表明，与基线水平相比，LT4 补充后心输出量（CO）、左心室射血分数（LVEF）和峰值 E 速度/峰值 A 速度的比值均显著增加。然而，我们没有发现心脏形态有明显变化的明确证据。
从 CO、LVEF 和 E/A 比值的明显变化来看，LT4 补充可以有效改善 SCH 患者普遍存在的心脏收缩和舒张功能障碍。本研究为成人 SCH 患者推荐 LT4 补充提供了证据。
