Department of Cardiology, Division of Medicine, Akershus University Hospital, Lørenskog, Norway.
Clin Chem. 2012 Nov;58(11):1565-73. doi: 10.1373/clinchem.2012.190868. Epub 2012 Sep 20.
Whether cardiac troponin concentrations are increased by reversible myocardial ischemia is controversial. Differences in the structure of cardiac troponin I (cTnI) and cTnT may have implications for diagnostic utility.
cTnI was measured with a prototype high-sensitivity (hs) assay in 198 patients referred for myocardial perfusion imaging (MPI) before exercise stress testing, immediately after, and 1.5 and 4.5 h later. We categorized patients according to MPI results and compared hs-cTnI concentrations with hs-cTnT concentrations.
Baseline hs-cTnI was higher in patients with reversible myocardial ischemia (n = 19) vs the other patients (n = 179): median 4.4 (quartiles 1-3: 2.3-7.1) vs 2.5 (1.4-4.3) ng/L, P = 0.003. Baseline hs-cTnI and hs-cTnT concentrations were correlated (r = 0.46, P < 0.001) and the areas under the ROC curve for hs-cTnI and hs-cTnT in diagnosing reversible ischemia were similar: 0.71 vs 0.69, P = 0.77. Whereas hs-cTnI increased immediately after exercise (P < 0.001 vs baseline measurements) in patients without ischemia, it increased after 4.5 h in patients with reversible ischemia (P = 0.01). The increment in hs-cTnI concentrations was comparable between groups; thus, measuring hs-cTnI after exercise stress testing did not improve diagnostic accuracy over baseline measurements, and hs-cTnI concentrations were not found to be associated with reversible myocardial ischemia in multivariate analysis. By linear regression analysis, age, male sex, history of hypertension, angiotensin-converting enzyme inhibitor use, and lower left ventricular ejection fraction were associated with higher baseline hs-cTnI concentrations.
In patients referred to MPI, hs-cTnI concentrations were not closely associated with reversible myocardial ischemia, but rather were influenced by variables associated with structural alterations of the myocardium.
心肌顿抑导致的可逆性心肌缺血是否会引起心肌肌钙蛋白浓度升高目前仍存在争议。心肌肌钙蛋白 I（cTnI）和 cTnT 的结构差异可能对诊断的实用性有影响。
在运动负荷试验前、运动后即刻以及 1.5 和 4.5 h 后，我们使用高敏（hs）检测方法对 198 例因疑似心肌灌注成像（MPI）而行心肌灌注成像检查的患者的 cTnI 进行了检测。我们根据 MPI 结果对患者进行了分类，并比较了 hs-cTnI 与 hs-cTnT 浓度。
与其他患者（n = 179）相比，可逆性心肌缺血患者（n = 19）的基线 hs-cTnI 更高：中位数为 4.4（1 四分位距3 四分位距：2.37.1）ng/L 比 2.5（1.4~4.3）ng/L，P = 0.003。基线 hs-cTnI 和 hs-cTnT 浓度呈正相关（r = 0.46，P < 0.001），hs-cTnI 和 hs-cTnT 对诊断可逆性缺血的 ROC 曲线下面积相似：0.71 比 0.69，P = 0.77。无缺血患者的 hs-cTnI 在运动后即刻升高（与基线测量值相比，P < 0.001），而可逆性缺血患者的 hs-cTnI 在 4.5 h 后升高（P = 0.01）。两组之间 hs-cTnI 浓度的增加幅度相似；因此，运动应激试验后测量 hs-cTnI 并未提高基线测量值的诊断准确性，并且在多变量分析中，hs-cTnI 浓度与可逆性心肌缺血并无关联。通过线性回归分析，年龄、男性、高血压病史、血管紧张素转换酶抑制剂的使用和较低的左心室射血分数与较高的基线 hs-cTnI 浓度相关。
在接受 MPI 检查的患者中，hs-cTnI 浓度与可逆性心肌缺血并无密切关联，而是受与心肌结构改变相关的变量影响。
