Using High-Sensitivity Cardiac Troponin T for Acute Cardiac Care

The recent approval of the fifth-generation cardiac troponin T assay, which has characteristics clinically of a high-sensitivity assay, has led to concern that the problems of increased sensitivity will be greater than the benefits. This will not be the case if cardiology, emergency medicine, and laboratory medicine combine to develop procedures for use of the assay. We advocate sex-specific 99th percentile upper reference limit values of 15 ng/L for men and 10 ng/L for women. We suggest a 2-hour rule-out strategy, including a value less than the 99th percentile upper reference limit and the lack of a change in values of <4 ng/L. Those with values >100 ng/L and or a changing pattern of values ≥10 ng/L are a population much more likely to have acute myocardial infarction. Most of the increment in elevated values will occur not in those with acute coronary problems but in those with primary cardiac disease like heart failure and those with primary noncardiac problems. The former belong on a cardiac service because they are at high risk. The latter should have therapy on the service most apt to provide optimal care for their primary diagnosis, with cardiac consultation as needed.     

Single High-Sensitivity Cardiac Troponin I to Rule Out Acute Myocardial Infarction

Background

This study examined the performance of single high-sensitivity cardiac troponin I (hs-cTnI) measurement strategies to rule out acute myocardial infarction.

Early Diagnosis of Myocardial Infarction With Point-of-Care High-Sensitivity Cardiac Troponin I

BackgroundUntil now, high-sensitivity cardiac troponin (hs-cTn) assays were mainly developed for large central laboratory platforms.ObjectivesThis study aimed to assess the clinical performance of a point-of-care (POC)-hs-cTnI assay in patients with suspected myocardial infarction (MI).MethodsThis study enrolled patients presenting to the emergency department with symptoms suggestive of MI. Two cardiologists centrally adjudicated the final diagnosis using all clinical data including cardiac imaging. The primary objective was to directly compare diagnostic accuracy of POC-hs-cTnI-TriageTrue versus best-validated central laboratory assays. Secondary objectives included the derivation and validation of a POC-hs-cTnI-TriageTrue–specific 0/1-h algorithm.ResultsMI was the adjudicated final diagnosis in 178 of 1,261 patients (14%). The area under the curve (AUC) for POC-hs-cTnI-TriageTrue at presentation was 0.95 (95% confidence interval [CI]: 0.93 to 0.96) and was at least comparable to hs-cTnT-Elecsys (AUC: 0.94; 95% CI: 0.93 to 0.96; p = 0.213) and hs-cTnI-Architect (AUC: 0.92; 95% CI: 0.90 to 0.93; p < 0.001). A single cutoff concentration <3 ng/l at presentation identified 45% of patients at low risk with a negative predictive value (NPV) of 100% (95% CI: 99.4% to 100%). A single cutoff concentration >60 ng/l identified patients at high risk with a positive predictive value (PPV) of 76.8% (95% CI: 68.9% to 83.6%). The 0/1-h algorithm ruled out 55% of patients (NPV: 100%; 95% CI: 98.8% to 100%), and ruled in 18% of patients (PPV: 76.8%; 95% CI: 67.2% to 84.7%). Ruled-out patients had cumulative event rates of 0% at 30 days and 1.6% at 2 years. This study confirmed these findings in a secondary analysis including hs-cTnI-Architect for central adjudication.ConclusionsThe POC-hs-cTnI-TriageTrue assay provides high diagnostic accuracy in patients with suspected MI with a clinical performance that is at least comparable to that of best-validated central laboratory assays. (Advantageous Predictors of Acute Coronary Syndromes Evaluation Study [APACE]; NCT00470587)     

Type 1 and 2 Myocardial Infarction and Myocardial Injury: Clinical Transition to High-Sensitivity Cardiac Troponin I

Background

Studies addressing patients with type 2 myocardial infarction and myocardial injury, including the impact of using high-sensitivity (hs) cardiac troponin (cTn) assays on their incidence are needed.

不稳定性心绞痛和急性心肌梗塞肌钙蛋白T变化的比较

目的 :比较不同急性冠状动脉综合征患者肌钙蛋白 T(Tn T)变化。　　方法 :不稳定性心绞痛 (UAP)、Q波型和非 Q波型急性心肌梗塞 (AMI)患者于急诊就诊时、住院后第 2、第 3和第 6日取血测定 Tn T水平。　　结果 :35 %的 UAP患者 Tn T表现为升高 ,其升高的幅度 (均 <3.0 ng/ ml)明显 <非 Q波型 AMI(2 4% >3.0 ng/ml)和 Q波型 AMI(90 % >3.0 ng/ ml) ,且一般 3天后即转为阴性 ,而 AMI患者 6天后多数仍为阳性。非 Q波型 AMI和Q波型 AMI急诊就诊时 Tn T的阳性率分别为 79.1%和 90 .7% ,住院后第 2日均达 10 0 % ,均明显高于同时间谷草转氨酶和肌酸激酶同工酶的阳性率 ,两组 Tn T阳性在持续时间上相似 ,但在升高幅度上有明显的区别。再灌注治疗可能会影响 Q波型 AMI患者 Tn T的自然变化规律。　　结论 :UAP患者 Tn T的变化与非 Q波型 AMI和 Q波型 AMI有显著的不同。     

High-Sensitivity Cardiac Troponin T levels in prehypertensive patients

Background: High-sensitivity cardiac troponin T (hs-cTNT) is an important non-invasive laboratory-based marker of subclinical myocardial injury. Prehypertension, which may be a precursor of hypertension, is a major public health issue. Our aim was to evaluate the importance of serum hs-cTnT as a marker predicting prehypertension.

Methods: A total of 100 subjects (45 women and 55 men) consisting of 50 consecutive prehypertensive patients with blood pressures between 120/80 and 139/89 mmHg and 50 normotensive patients with blood pressures < 120/80 mmHg were enrolled prospectively. The hs-cTNT level was calculated and compared between the two groups. Echocardiographic examinations were performed in all patients.

Results: The hs-cTnT level was significantly higher in the prehypertensive group (p < 0.001) and was positively correlated with prehypertension (r = 0.625, p < 0.001). Hs-cTnT was an independent predictor of prehypertension (odds ratio = 1.043, 95% confidence interval [CI] 1.019–1.067, p < 0.001). An Hs-cTnT level of 0.55 ng/L was predictive of prehypertension with a sensitivity of 86% and specificity of 60% (area under the curve = 0.861; 95% CI, 0.787–0.935; p < 0.001).

Conclusion: hs-cTnT may complement other diagnostic biomarkers in predicting prehypertension.

Abbrevations: high-sensitivity cardiac troponin T, prehypertension, subclinical myocardial injury     

冠状动脉旁路移植术治疗肌钙蛋白I恢复正常后急性心肌梗死

目的 急性心肌梗死(AMI)后肌钙蛋白I(cTnI)的升高和降低可以指导治疗和预测冠状动脉旁路移植术(CABG)围手术期并发症及预后,探讨急性心肌梗死在肌钙蛋白I恢复正常后行冠状动脉旁路移植术的手术效果。方法 2011年1月至2015年12月236例患者在急性心肌梗死后肌钙蛋白I恢复正常后30天内行CABG术,所有病人均测定术前、术后cTnI变化和持续时间。其中,男138例、女98例,年龄43～86岁,平均(63.53±9.26)岁;非ST段抬高性心肌梗死189例,ST段抬高性心肌梗死47例。术中行非体外循环CABG(OPCABG)229例,体外循环辅助心脏不停跳下CABG(on pump beating heart CABG)术7例。 结果 心梗后肌钙蛋白I恢复正常时间为2-18天,平均(5.41±3.25)天,心梗后手术时间4-29天,平均(9.32±7.15)天,搭桥数1-5支,平均(2.61±1.23)支,应用主动脉内球囊反搏(IABP)8例,住院死亡3例,死亡率1.69%(3/236)。结论 血流动力学相对稳定的AMI患者cTnI正常后尽早行CABG可以取得良好的治疗效果。     

Early Diagnosis of Myocardial Infarction Using Absolute and Relative Changes in Cardiac Troponin Concentrations

Background

Absolute changes in high-sensitivity cardiac troponin T (hs-cTnT) seem to have higher diagnostic accuracy in the early diagnosis of acute myocardial infarction compared with relative changes. It is unknown whether the same applies to high-sensitivity cardiac troponin I (hs-cTnI) assays and whether the combination of absolute and relative change might further increase accuracy.

Methods

In a prospective, international multicenter study, high-sensitivity cardiac troponin (hs-cTn) was measured with 3 novel assays (hs-cTnT, Roche Diagnostics Corp, Indianapolis, Ind; hs-cTnI, Beckman Coulter Inc, Brea, Calif; hs-cTnI, Siemens, Munich, Germany) in a blinded fashion at presentation and after 1 and 2 hours in a blinded fashion in 830 unselected patients with suspected acute myocardial infarction. The final diagnosis was adjudicated by 2 independent cardiologists.

Results

The area under the receiver operating characteristic curve for diagnosing acute myocardial infarction was significantly higher for 1- and 2-hour absolute versus relative hs-cTn changes for all 3 assays (P < .001). The area under the receiver operating characteristic curve of the combination of 2-hour absolute and relative change (hs-cTnT 0.98 [95% confidence interval {CI}, 0.97-0.99]; hs-cTnI, Beckman Coulter Inc, 0.97 [95% CI, 0.96-0.99]; hs-cTnI, Siemens, 0.96 [95% CI, 0.93-0.99]) were high and provided some benefit compared with the use of absolute change alone for hs-cTnT, but not for the hs-cTnI assays. Reclassification analysis confirmed the superiority of absolute changes versus relative changes.

Conclusions

Absolute changes seem to be the preferred metrics for both hs-cTnT and hs-cTnI in the early diagnosis of acute myocardial infarction. The combination of absolute and relative changes provides a small added value for hs-cTnT, but not for hs-cTnI.     

心肌肌钙蛋白T与急性冠状动脉综合征

急性冠状动脉综合征代表冠状动脉病变程度不同的一组疾病 ,其临床表现为不稳定性心绞痛 ,急性心肌梗死和猝死。其共同的病理生理基础为急性粥样斑块破裂、血小板激活、血栓形成导致血管腔不同程度的阻塞[1] 。其结局和治疗措施不同 ,但是其临床诊断和预后分级常很困难。心肌肌钙蛋白 T( cardiac troponin T,c Tn T)是心肌细胞肌钙蛋白复合物的亚单位。心肌细胞受损时 ,c Tn T释放入血液 ,其浓度与心肌损伤程度紧密联系 [2 ]。 c Tn T与心肌细胞损伤的传统生化指标CK- MB相比 ,c Tn T有以下几个优点 :c Tn T的氨基酸序列不同于骨骼肌…     

Clinical Impact of High-Sensitivity Cardiac Troponin T Implementation in the Community

BackgroundLimited U.S. data exist regarding high-sensitivity cardiac troponin (cTn) implementation.ObjectivesThis study sought to evaluate the impact of high-sensitivity cardiac troponin T (cTnT) implementation.MethodsObservational U.S. cohort study of emergency department (ED) patients undergoing measurement of cTnT during the transition from 4th (pre-implementation March 12, 2018, to September 11, 2018) to 5th generation (Gen) cTnT (post-implementation September 12, 2018, to March 11, 2019). Diagnoses were adjudicated following the Fourth Universal Definition of Myocardial Infarction (MI). Resources evaluated included length of stay, hospitalizations, and cardiac testing.ResultsIn this study, 3,536 unique patients were evaluated, including 2,069 and 2,491 ED encounters pre- and post-implementation. Compared with 4th Gen cTnT, encounters with ≥1 cTnT >99th percentile increased using 5th Gen cTnT (15% vs. 47%; p < 0.0001). Acute MI (3.3% vs. 8.1%; p < 0.0001) and myocardial injury (11% vs. 38%; p < 0.0001) increased. Although type 1 MIs increased (1.7% vs. 2.9%; p = 0.0097), the overall MI increase was largely due to more type 2 MIs (1.6% vs. 5.2%; p < 0.0001). Women were less likely than men to have MI using 4th Gen cTnT (2.3% vs. 4.4%; p = 0.008) but not 5th Gen cTnT (7.7% vs. 8.5%; p = 0.46). Overall length of stay and stress testing were reduced, and angiography was increased (all p < 0.05). Among those without cTnT increases, there were more ED discharges and a reduction in length of stay, echocardiography, and stress tests (all p < 0.05).ConclusionsHigh-sensitivity cTnT implementation resulted in a marked increase in myocardial injury and MI, particularly in women and patients with type 2 MI. Despite this, except for angiography, overall resource use did not increase. Among those without cTnT increases, there were more ED discharges and fewer cardiac tests.