美国一项研究显示，随着一种高敏感性检测方法的使用，在血液中检测到心肌肌钙蛋白T（这是一种心肌特异性蛋白）与结构性心脏病及全因死亡风险的增加有关。研究论文12月8日发表于《美国医学会杂志》上。
心肌肌钙蛋白T（cTnT）是一种更好的诊断心梗的生物标志物，人们越来越认识到肌钙蛋白浓度的增加会在数种慢性疾病状态中被检测到，其中包括冠状动脉疾病（CAD）、心衰及慢性肾病（CKD）。根据文章的背景资料，某些研究提示，肌钙蛋白可能对发现亚临床的心血管疾病及在一般人群中评估心血管疾病的风险有用；然而，标准化检测的低敏感度会限制人们对肌钙蛋白测定的临床应用。
文章的作者写道：“最近，一种对cTnT的高敏感检测方法已经研发出来，它可以检测到比标准测试所能探测到的浓度低大约10倍的cTnT。在罹患慢性心衰和慢性冠心病的患者中，该高度敏感的测试方法在几乎所有的人中都能找到其循环血液中的cTnT。而较高浓度的cTnT与心血管死亡率的增加有着很强的关联性。”
达拉斯德州大学西南医学中心的James A. de Lemos及其同事开展了一项研究，旨在确定用高敏感性检测来探测人群中cTnT的流行程度，并对用这一新的测试方法所测得的cTnT浓度是否与心脏异常及随后的死亡有关进行了评估。研究人员在3546名有着多种族裔背景的年龄30-65岁的人中用标准测试法及高敏感性测试法对心肌肌钙蛋白T进行了检测。这些人是在2000至2002年期间参加达拉斯心脏研究的人。对这些人的死亡率跟踪是在2007年完成的。参与者根据其cTnT的浓度被分置于5个类别之中。这些人的心脏结构及功能是通过磁共振成像来测定的。
研究人员发现，在达拉斯县的成年人中，高敏感性检测可检测到的cTnT流行率为25%，而在标准检测中，其流行率为0.7%。按照性别和种族来分，该流行率会有很大的差异：男性被探测到的机会要比女性高3倍（37.1% 对 12.9%），而在黑人参与者中探测到cTnT的可能性要比在西语裔或白人显著要高。 可探测到的cTnT的比例会随着年龄而变化，其变化范围为：从40-50岁的14%至60-65岁时的57.6%。
文章的作者提示，他们在一般人群中所发现的可探测到的cTnT的高比例可能会对使用高敏感性肌钙蛋白测试以诊断医院中患者的心梗有着重要且复杂的影响。“在那些有着疑似心肌梗塞表现的患者中，高敏感性检测可提高诊断的敏感性，特别是在症状出现的早期；但高敏感性测试会降低检验的特异性。当其被用于在临床上高度疑似心肌梗塞的病人时，其最终结果是改善检测的精确性。”
研究人员补充说，这些发现提示，需要开展进一步的研究以评估用高敏感性检测来测定cTnT浓度是否会增加传统心血管风险因子的价值。
推荐原文出处：
JAMA. doi: 10.1001/jama.2010.1768
Association of Troponin T Detected With a Highly Sensitive Assay and Cardiac Structure and Mortality Risk in the General Population
James A. de Lemos, MD; Mark H. Drazner, MD, MSc; Torbjorn Omland, MD, PhD; Colby R. Ayers, MS; Amit Khera, MD, MSc; Anand Rohatgi, MD; Ibrahim Hashim, PhD, MSc; Jarett D. Berry, MD, MS; Sandeep R. Das, MD, MPH; David A. Morrow, MD, MPH; Darren K. McGuire, MD, MHSc
AbstractContext Detectable levels of cardiac troponin T (cTnT) are strongly associated with structural heart disease and increased risk of death and adverse cardiovascular events; however, cTnT is rarely detectable in the general population using standard assays.
Objectives To determine the prevalence and determinants of detectable cTnT in the population using a new highly sensitive assay and to assess whether cTnT levels measured with the new assay associate with pathological cardiac phenotypes and subsequent mortality.
Design, Setting, and Participants Cardiac troponin T levels were measured using both the standard and the highly sensitive assays in 3546 individuals aged 30 to 65 years enrolled between 2000 and 2002 in the Dallas Heart Study, a multiethnic, population-based cohort study. Mortality follow-up was complete through 2007. Participants were placed into 5 categories based on cTnT levels.
Main Outcome Measures Magnetic resonance imaging measurements of cardiac structure and function and mortality through a median of 6.4 (interquartile range, 6.0-6.8) years of follow-up.
Results In Dallas County, the prevalence of detectable cTnT (≥0.003 ng/mL) was 25.0% (95% confidence interval [CI], 22.7%-27.4%) with the highly sensitive assay vs 0.7% (95% CI, 0.3%-1.1%) with the standard assay. Prevalence was 37.1% (95% CI, 33.3%-41.0%) in men vs 12.9% (95% CI, 10.6%-15.2%) in women and 14.0% (95% CI, 11.2%-16.9%) in participants younger than 40 years vs 57.6% (95% CI, 47.0%-68.2%) in those 60 years and older. Prevalence of left ventricular hypertrophy increased from 7.5% (95% CI, 6.4%-8.8%) in the lowest cTnT category (&0.003 ng/mL) to 48.1% (95% CI, 36.7%-59.6%) in the highest (≥0.014 ng/mL) (P & .001); prevalence of left ventricular systolic dysfunction and chronic kidney disease also increased across categories (P & .001 for each). During a median follow-up of 6.4 years, there were 151 total deaths, including 62 cardiovascular disease deaths. All-cause mortality increased from 1.9% (95% CI, 1.5%-2.6%) to 28.4% (95% CI, 21.0%-37.8%) across higher cTnT categories (P & .001). After adjustment for traditional risk factors, C-reactive protein level, chronic kidney disease, and N-terminal pro-brain-type natriuretic peptide level, cTnT category remained independently associated with all-cause mortality (adjusted hazard ratio, 2.8 [95% CI, 1.4-5.2] in the highest category). Adding cTnT categories to the fully adjusted mortality model modestly improved model fit (P = .02) and the integrated discrimination index (0.010 [95% CI, 0.002-0.018]; P = .01).
Conclusion In this population-based cohort, cTnT detected with a highly sensitive assay was associated with structural heart disease and subsequent risk for all-cause mortality.
KEYWORDS: BIOLOGICAL ASSAY, CARDIOVASCULAR DISEASES, MORTALITY, RISK FACTORS, TROPONIN T.
