Zhang, Ming

Hypothyroidism, also called&nbsp;underactive thyroid&nbsp;or&nbsp;low thyroid, is a&nbsp;disorder of the endocrine system&nbsp;in which the&nbsp;thyroid gland&nbsp;does not produce enough&nbsp;thyroid hormone.&nbsp;It can cause a number of symptoms, such as&nbsp;poor ability to tolerate cold, a&nbsp;feeling of tiredness,&nbsp;constipation,&nbsp;depression, and&nbsp;weight gain.&nbsp;Occasionally there may be swelling of the front part of the neck due to&nbsp;goiter.&nbsp;Untreated cases of hypothyroidism during&nbsp;pregnancy&nbsp;can lead to delays in&nbsp;growth and intellectual development&nbsp;in the baby or&nbsp;congenital iodine deficiency syndrome.<br /> Worldwide,&nbsp;too little iodine&nbsp;in the diet is the most common cause of hypothyroidism.&nbsp;Hashimoto's thyroiditis&nbsp;is the most common cause of hypothyroidism in countries with sufficient dietary iodine.&nbsp;Less common causes include previous treatment with&nbsp;radioactive iodine, injury to the&nbsp;hypothalamus&nbsp;or the&nbsp;anterior pituitary&nbsp;gland, certain medications,&nbsp;a lack of a functioning thyroid at birth, or previous&nbsp;thyroid surgery.&nbsp;The diagnosis of hypothyroidism, when suspected, can be confirmed with&nbsp;blood tests&nbsp;measuring&nbsp;thyroid-stimulating hormone&nbsp;(TSH) and&nbsp;thyroxine&nbsp;levels.

AbstractBackgroundLarge cohort studies provide conflicting evidence regarding the prognostic value of early repolarization pattern (ERP) in the general population, complicated by the complex or heterogeneous definitions of ERP applied in different studies.HypothesisWe hypothesized that ERP was associated with increased cardiovascular risk with the definition of ERP recommended by the expert consensus statements.MethodsA total of 13673 middle‐aged subjects from the prospective, population‐based Atherosclerosis Risk in Communities (ARIC) study were included in this analysis. Cox models were used to estimate the hazard ratios (HRs) adjusted for possible confounding factors. ERP was defined as ST‐segment elevation ≥0.1mV at the end of the QRS or J wave on the QRS downstroke in two or more contiguous leads.ResultsCompared with those without ERP, subjects with ERP had a significantly increased risk of developing sudden cardiac death (SCD) (HR, 1.48; 95% CI, 1.08–2.04) and death from coronary heart disease (CHD) (HR, 1.45; 95% CI, 1.10–1.92) after a median follow‐up of 20.1 years. ERP was significantly predictive of SCD in females, whites, younger people, and subjects with relatively low cardiovascular risk. ERP with ST‐segment elevation appeared to indicate poor cardiovascular outcomes. ERP was associated with an absolute risk increase of 93.3 additional SCDs per 100 000 person‐years.ConclusionsOur findings suggest that ERP was an independent predictor of SCD and CHD death in the middle‐aged biracial population.

Background Hypothyroidism is associated with an increased risk of coronary artery disease, beyond that which can be explained by its association with conventional cardiovascular risk factors. Coronary endothelial dysfunction precedes atherosclerosis, has been linked to adverse cardiovascular events, and may account for some of the increased risk in patients with hypothyroidism. The aim of this study was to determine whether there is an association between epicardial and microvascular coronary endothelial dysfunction and hypothyroidism. Methods and Results In 1388 patients (mean age 50.5 [12.3] years, 34% male) presenting with stable chest pain to Mayo Clinic, Rochester, MN for diagnostic coronary angiography, and who were found to have nonobstructive coronary artery disease (<40% stenosis), we invasively assessed coronary artery endothelial‐dependent microvascular and epicardial function by evaluating changes in coronary blood flow (% Δ CBF Ach) and diameter (% Δ CAD Ach), respectively, in response to intracoronary infusions of acetylcholine. Patients were divided into 2 groups: hypothyroidism, defined as a documented history of hypothyroidism or a thyroid‐stimulating hormone ( TSH ) >10.0 mU / mL , n=188, and euthyroidism, defined as an absence of a history of hypothyroidism in the clinical record and/or 0.3< TSH ≤10.0 mU / mL , n=1200. Subjects with a history of hypothyroidism had a significantly lower % Δ CBF Ach (48.26 [80.66] versus 64.58 [128.30]) compared to patients with euthyroidism, while the % Δ CAD Ach did not vary significantly between groups. After adjusting for covariates, females with hypothyroidism still had a significantly lower % Δ CBF Ach (estimated difference in % Δ CBF Ach [ SE ]: −16.79 [8.18]). Conclusions Hypothyroidism in women is associated with microvascular endothelial dysfunction, even after adjusting for confounders, and may explain some of the increased risk of cardiovascular disease in these patients.

Background The study compared downstream coronary and conduit disease progression in the left anterior descending coronary artery treated with coronary artery bypass grafting using the left internal mammary artery ( LIMA ) versus percutaneous coronary intervention with bare metal stent ( BMS ) or drug eluting stent ( DES ). Methods and Results A total of 12 301 consecutive patients underwent isolated primary coronary revascularization, of which 2386 met our inclusion criteria (Percutaneous coronary intervention, n=1450; coronary artery bypass grafting, n=936). Propensity score analysis matched 628 patients, of which 468 were treated to the left anterior descending with coronary artery bypass grafting with LIMA (n=314), percutaneous coronary intervention with BMS (n=94), and DES (n=60). Coronary angiograms were analyzed by quantitative coronary angiography ( QCA ; n=433). Cumulative downstream coronary and conduit disease progression were estimated by Kaplan–Meier method and effect of treatment type by Cox proportional hazard models. Patients treated with LIMA had significantly lower risk of downstream coronary disease progression at follow‐up angiogram compared with BMS and DES (hazard ratio [ HR ] [95% CI ], 0.34; [0.20–0.59]; P =0.0002; and HR [95% CI ], 0.39; [0.20–0.79]; P =0.01, respectively). LIMA was associated with a lower risk of conduit disease progression compared to BMS and DES ( HR [95% CI ], 0.18; [0.12–0.28]; P <0.001; and HR [95% CI ], 0.27; [0.16–0.46]; P <0.001, respectively). BMS was associated with higher HR for downstream coronary and conduit disease progression compared with DES , but the difference did not reach statistical significance ( HR [95% CI], 1.13; [0.57–2.36]; P =0.73; and HR [95% CI ], 1.46; [0.88–2.50]; P =0.14, respectively). Conclusions LIMA grafting to left anterior descending is associated with significantly lower risk of downstream coronary and conduit disease progression compared to percutaneous coronary intervention with BMS and DES .