High-sensitivity cardiac troponins: no more 'negatives'

Kinetics of plasma von Willebrand factor in acute myocardial infarction patients: a meta-analysis

Previous studies have shown a variation in plasma level of von Willebrand factor (vWF) in acute myocardial infarction (AMI) patients but with contentious results. In this study, we performed a meta-analysis to evaluate the kinetics of plasma vWF after AMI. A total of 11 qualified studies were obtained through systematical search in PubMed, Web of science, Cochrane Library database and CNKI, followed by search of reference lists, involving 519 AMI patients and 466 non-AMI controls. The standard mean difference (SMD) and 95% confidence intervals (95% CI) were calculated using random-effects model. Results indicated that the plasma vWF was significantly increased in the first several hours after onset of AMI (SMD = 1.94, 95% CI = 1.39-2.48, P < 0.001) and stayed at high level until 24 h (SMD = 1.17, 95% CI = 0.45-1.89, P = 0.001). Elevated level of vWF appeared to persist for one week and reduced to normal until the fourteenth day after AMI (SMD = 0.44, 95% CI = -0.14-1.02, P = 0.14). Subgroup analysis revealed that the high level of vWF lasted just for 1 day in patients with a symptom duration ≤ 6 h before admission. For patients with a symptom duration > 6 h, elevated vWF was found in all 7 days except day 1. Our findings determined the kinetics of plasma vWF after AMI, and might provide a new insight in monitoring AMI progression.

High-sensitivity cardiac troponin testing in routine practice: economic and organizational advantages

Very seldom, if ever, a single laboratory test has provided such a paradigm shift in the managed care as cardiac troponin (cTn) testing. More than twenty years of improvements in test design and analytical features have contributed to revolutionize the clinical recommendations and guidelines, and the diagnosis of myocardial infarction (MI) is now highly dependent upon the kinetics of cTn within a suggestive clinical setting. Despite the advent of high-sensitivity cTn (HS-cTn) immunoassays has allowed a more accurate and timely diagnosis as well as a higher prognostic accuracy, the focus is now shifting on the most suitable algorithms and on a comprehensive approach to the clinical management of acute coronary syndrome (ACS). In this article we aim to discuss the implications of HS-cTn testing for ruling out and ruling in ACS. In the latter instance, main improvements are related to ACS diagnosis in women, in whom this pathology is still often underdiagnosed or misdiagnosed. A quick and accurate rule out will also regarded as a great advantage from both an organizational and economic standpoint. The advantages that will stem from this new approach have been recently assessed, and shortening of repeated testing 1 or 2 h from conventional algorithms entailing blood sampling at 3 and 6 h seems attainable. The larger benefits will definitely occur in clinical settings where the actual diagnosis rate of MI among patients with suspect ACS is lower and, consequently, the negative predictive value (NPV) of HS-cTn is the highest.

An historical approach to the diagnostic biomarkers of acute coronary syndrome

Suspected acute myocardial infarction (AMI) is one of the leading causes of admission to the emergency departments in Western countries but also an increasing cause in many other nations. The diagnosis of AMI involves the evaluation of clinical signs and symptoms, electrocardiographic assessment, and measurement of cardiac circulating biomarkers. In the last sixty years, the use of laboratory markers has changed considerably. Early biomarkers assessment has entailed testing for total enzyme activity of aspartate aminotransferase (AST), lactate dehydrogenase (LDH) and creatine kinase (CK). Advances in electrophoresis allowed the identification of more cardio-specific isoenzymes of both CK and LDH, thus leading to the introduction of the CK-MB and LDH-1 activity assays. Soon thereafter, the development of immunoassays, as well as technical advances in automation, allowed the measurements of the CK-MB in mass rather than in activity and myoglobin. Currently, cardiac troponins have the highest sensitivity and specificity for myocardial necrosis and represent the biochemical gold standard for diagnosing AMI. This review provides a chronology of the major events which marked the evolution of cardiac biomarkers testing and the development of the relative assays from the first introduction of AST in the 1950s to the last high sensitivity troponin immunoassays in the 2010s.

Recent advances in the diagnosis and treatment of acute myocardial infarction

The Third Universal Definition of Myocardial Infarction (MI) requires cardiac myocyte necrosis with an increase and/or a decrease in a patient’s plasma of cardiac troponin (cTn) with at least one cTn measurement greater than the 99^th percentile of the upper normal reference limit during: (1) symptoms of myocardial ischemia; (2) new significant electrocardiogram (ECG) ST-segment/T-wave changes or left bundle branch block; (3) the development of pathological ECG Q waves; (4) new loss of viable myocardium or regional wall motion abnormality identified by an imaging procedure; or (5) identification of intracoronary thrombus by angiography or autopsy. Myocardial infarction, when diagnosed, is now classified into five types. Detection of a rise and a fall of troponin are essential to the diagnosis of acute MI. However, high sensitivity troponin assays can increase the sensitivity but decrease the specificity of MI diagnosis. The ECG remains a cornerstone in the diagnosis of MI and should be frequently repeated, especially if the initial ECG is not diagnostic of MI.

There have been significant advances in adjunctive pharmacotherapy, procedural techniques and stent technology in the treatment of patients with MIs. The routine use of antiplatelet agents such as clopidogrel, prasugrel or ticagrelor, in addition to aspirin, reduces patient morbidity and mortality. Percutaneous coronary intervention (PCI) in a timely manner is the primary treatment of patients with acute ST segment elevation MI. Drug eluting coronary stents are safe and beneficial with primary coronary intervention. Treatment with direct thrombin inhibitors during PCI is non-inferior to unfractionated heparin and glycoprotein IIb/IIIa receptor antagonists and is associated with a significant reduction in bleeding. The intra-coronary use of a glycoprotein IIb/IIIa antagonist can reduce infarct size. Pre- and post-conditioning techniques can provide additional cardioprotection. However, the incidence and mortality due to MI continues to be high despite all these recent advances. The initial ten year experience with autologous human bone marrow mononuclear cells (BMCs) in patients with MI showed modest but significant increases in left ventricular (LV) ejection fraction, decreases in LV end-systolic volume and reductions in MI size. These studies established that the intramyocardial or intracoronary administration of stem cells is safe. However, many of these studies consisted of small numbers of patients who were not randomized to BMCs or placebo. The recent LateTime, Time, and Swiss Multicenter Trials in patients with MI did not demonstrate significant improvement in patient LV ejection fraction with BMCs in comparison with placebo. Possible explanations include the early use of PCI in these patients, heterogeneous BMC populations which died prematurely from patients with chronic ischemic disease, red blood cell contamination which decreases BMC renewal, and heparin which decreases BMC migration. In contrast, cardiac stem cells from the right atrial appendage and ventricular septum and apex in the SCIPIO and CADUCEUS Trials appear to reduce patient MI size and increase viable myocardium. Additional clinical studies with cardiac stem cells are in progress.

Chest pain and high-sensitivity troponin: What is the evidence?

The number of attendances and admissions of patients with chest pain to hospitals in England and Wales is increasing. Initial assessment may be unrewarding. Consequently, cardiac troponin has become the mainstay of investigation for non-ST-segment-elevation myocardial infarction and unstable angina, although only a small proportion of patients are eventually diagnosed as such. Current National Institute for Healthcare and Clinical Excellence guidance recommends measuring cardiac troponin levels on presentation and 10-12 h after onset of symptoms. A more effective diagnostic tool is needed. The aims are twofold: to increase accuracy of acute coronary syndrome diagnosis thus implementing the most appropriate management at an earlier stage while reducing costs and to provide a more rapid diagnosis to ease the anxieties of patients. Three key issues have been highlighted. The first is that many current studies do not have a 'normal/reference' population, making comparison between two studies difficult to interpret. Second, whether newer 'high-sensitivity' cardiac troponin tests can be used to rule out a myocardial infarction in a patient with chest pain is discussed. Third, whether a 'high-sensitivity' cardiac troponin has great enough specificity to differentiate between the number of other causes of raised troponin in a single test or whether serial testing is needed is assessed. A strategy for such serial testing is discussed. Finally, use of 'high-sensitivity' cardiac troponin in risk stratification of other disease processes is highlighted, which is likely to become common practice, changing the way we manage patients with, and without, chest pain.

Continuous cardiac troponin I release in Fabry disease

BACKGROUND

Fabry disease (FD) is a rare lysosomal storage disorder also affecting the heart. The aims of this study were to determine the frequency of cardiac troponin I (cTNI) elevation, a sensitive parameter reflecting myocardial damage, in a smaller cohort of FD-patients, and to analyze whether persistent cTNI can be a suitable biomarker to assess cardiac dysfunction in FD.

METHODS

cTNI values were determined at least twice per year in 14 FD-patients (6 males and 8 females) regularly followed-up in our centre. The data were related to other parameters of heart function including cardiac magnetic resonance imaging (cMRI).

RESULTS

Three patients (21%) without specific vascular risk factors other than FD had persistent cTNI-elevations (range 0.05-0.71 ng/ml, normal: <0.01). cMRI disclosed late gadolinium enhancement (LGE) in all three individuals with cTNI values ≥0.01, while none of the 11 patients with cTNI <0.01 showed a pathological enhancement (p<0.01). Two subjects with increased cTNI-values underwent coronary angiography, excluding relevant stenoses. A myocardial biopsy performed in one during this procedure demonstrated substantial accumulation of globotriaosylceramide (Gb3) in cardiomyocytes.

CONCLUSION

Continuous cTNI elevation seems to occur in a substantial proportion of patients with FD. The high accordance with LGE, reflecting cardiac dysfunction, suggests that cTNI-elevation can be a useful laboratory parameter for assessing myocardial damage in FD.