Cardiac troponin T in pregnant women having intravenous tocolytic therapy

Reference intervals for clinical biochemistry and haematology tests during normal pregnancy

BACKGROUND

Pregnancy induces physiological changes which affect biochemical and haematological parameters. As the significance of laboratory test results change throughout pregnancy, the reference interval (RI) or key result interpretive guide should be specific to pregnancy. This study sought to establish trimester-specific-RIs for routine biochemical and haematological tests in healthy white European women with singleton pregnancies with comparison to RIs for non-pregnant European adults.

METHODS

A retrospective analysis of a prospective longitudinal single-centre study of healthy pregnant women conducted between November 2018 and December 2020 in a tertiary academic hospital with approximately 3000 births annually. Inclusion criteria: signed informed consent, age ≥18 years, white European, body mass index (BMI) <25 kg/m2, blood pressure <140/90mmHg, non-smoker, no previous pathology or gestational diabetes. Trimester defined as T1: up to 13 weeks + 6 days, T2: 14-27 weeks + 6 days and T3: ≥28-41 weeks + 6 days. Baseline demographics, anthropometric and laboratory measurements were recorded. In total, 31 biochemical and 10 haematological ISO15189:2012 accredited tests were measured using Roche Cobas® and Sysmex XN-9100™ analysers, respectively. RIs were established according to the International Federation of Clinical Chemistry (IFCC) recommended method.

RESULTS

Apparently healthy pregnant women (n = 124) with bio-banked serum samples in each trimester were recruited. At the booking visit, 49.2% (n = 61) of participants were nulliparous, with median age of 34.4 (IQR: 31.3-37.3) years, gestational age of 89 (IQR: 84-93) days, BMI of 22.5 (IQR: 21.0-23.7) kg/m² and systolic and diastolic blood pressure of 116 (110-125) mmHg and 67 (61-75) mmHg, respectively.

CONCLUSIONS

Normative trimester-specific biological intervals for routinely requested biochemical and haematological medical laboratory tests were established. These RIs will be invaluable to result interpretation and the management of pregnant women.

Coronary Events in the Pregnant Patient: Who Is at Risk and How Best to Manage?

Coronary events in pregnancy are a rare but growing cause of maternal morbidity and mortality. Pregnancy presents unique challenges across a broad spectrum of disciplines and requires a multidisciplinary approach to optimise maternal and fetal outcomes. The early involvement of the "cardio-obstetrics" team in prepregnancy counselling, the antenatal period, delivery, and postpartum is vital to ensuring better outcomes for patients at high risk of coronary pathology. The overall risk for coronary events complicating pregnancy is increasing owing to a number of factors, including advancing maternal age and increases in traditional cardiac risk factors contributing to higher rates of maternal morbidity and mortality. The majority of pregnant women experiencing a coronary event do not have previous coronary disease, and the pathologic mechanisms involved are predominantly nonatherosclerotic. Diagnosis and management should follow standard guideline-based practices for acute coronary syndrome (ACS), including the use of diagnostic coronary angiography to guide percutaneous intervention when needed. Management of ACS should not be delayed to facilitate delivery, which can proceed following stent implantation and dual antiplatelet therapy. The timing and mode of delivery should be based on assessment of maternal and fetal status, but vaginal delivery is preferred when possible. This review aims to provide an overview of the major etiologies, risk factors, diagnoses, and management strategies for patients at risk of or presenting with coronary events in pregnancy.

Cardiac-specific troponins in uncomplicated pregnancy and pre-eclampsia: A systematic review

Background

The risk of myocardial infarction (MI) increases during pregnancy, particularly in women with pre-eclampsia. MI is diagnosed by measuring high blood levels of cardiac-specific troponin (cTn), although this may be elevated in women with pre-eclampsia without MI, which increases diagnostic uncertainty. It is unclear how much cTn is elevated in uncomplicated and complicated pregnancy, which may affect whether the existing reference intervals can be used in pregnant women. Previous reviews have not investigated high-sensitivity troponin in pregnancy, compared to older, less sensitive methods.

Methods

Electronic searches using the terms “troponin I” or “troponin T”, and “pregnancy”, “pregnancy complications” or “obstetrics”. cTn levels were extracted from studies of women with uncomplicated pregnancies or pre-eclampsia.

Results

The search identified ten studies with 1581 women. Eight studies used contemporary methods that may be too insensitive to use reliably in this clinical setting. Two studies used high-sensitivity assays, with one reporting an elevation in troponin I (TnI) in pre-eclampsia compared to uncomplicated pregnancy, and the other only examining women with pre-eclampsia.

Seven studies compared cTn between women with pre-eclampsia or uncomplicated pregnancy using any assay. Seven studies showed elevated TnI in pre-eclampsia compared to uncomplicated pregnancy or non-pregnant women. One study measured troponin T (TnT) in pregnancy but did not examine pre-eclampsia.

Conclusion

TnI appears to be elevated in pre-eclampsia, irrespective of methodology, which may reflect the role of cardiac stress in this condition. TnI may be similar in healthy pregnant and non-pregnant women, but we found no literature reporting pregnancy-specific reference intervals using high-sensitivity tests. This limits broader application of cTn in pregnancy. There is a need to define reference intervals for cTn in pregnant women, which should involve serial sampling throughout pregnancy, with careful consideration for gestational age and body mass index, which cause dynamic changes in normal maternal physiology.

Changes in biochemical tests in pregnancy and their clinical significance

Interpretation of laboratory investigations relies on reference intervals. Physiological changes in pregnancy may result in significant changes in normal values for many biochemical assays, and as such results may be misinterpreted as abnormal or mask a pathological state. The aims of this review are as follows: 1. To review the major physiological changes in biochemical tests in normal pregnancy. 2. To outline where these physiological changes are important in interpreting laboratory investigations in pregnancy. 3. To document the most common causes of abnormalities in biochemical tests in pregnancy, as well as important pregnancy-specific causes.

Comprehensive review of cardiovascular toxicity of drugs and related agents

Cardiovascular diseases are a leading cause of morbidity and mortality in most developed countries of the world. Pharmaceuticals, illicit drugs, and toxins can significantly contribute to the overall cardiovascular burden and thus deserve attention. The present article is a systematic overview of drugs that may induce distinct cardiovascular toxicity. The compounds are classified into agents that have significant effects on the heart, blood vessels, or both. The mechanism(s) of toxic action are discussed and treatment modalities are briefly mentioned in relevant cases. Due to the large number of clinically relevant compounds discussed, this article could be of interest to a broad audience including pharmacologists and toxicologists, pharmacists, physicians, and medicinal chemists. Particular emphasis is given to clinically relevant topics including the cardiovascular toxicity of illicit sympathomimetic drugs (e.g., cocaine, amphetamines, cathinones), drugs that prolong the QT interval, antidysrhythmic drugs, digoxin and other cardioactive steroids, beta-blockers, calcium channel blockers, female hormones, nonsteroidal anti-inflammatory, and anticancer compounds encompassing anthracyclines and novel targeted therapy interfering with the HER2 or the vascular endothelial growth factor pathway.

Serum troponin in neonatal intensive care

Cardiac troponins have a major role in screening and diagnosis of myocardial ischaemia in adults and children. Their introduction has redefined the diagnosis of myocardial infarction in adults and provided valuable prognostic information. In the paediatric population, troponins show a good correlation with the extent of myocardial damage following cardiac surgery and cardiotoxic medication, and can be used as predictors of subsequent cardiac recovery and mortality. This review discusses the current established reference values in term and preterm infants and demonstrates their potential use in neonatology. They may serve as a useful adjunct in the assessment of the magnitude of myocardial injury in respiratory distress syndrome and asphyxia. They may also benefit centres without on-site echocardiography with some evidence showing good correlation with echo-derived markers of myocardial function. The use of troponins in the neonatal unit remains a research tool. More work is needed to explore their prognostic role and monitoring response to treatment following cardioprotective strategies. In preterm infants the effect of inotropes on myocardial function needs further study and troponin may form an integral part of this research.

A pregnant woman with acute myocardial infarction due to coronary artery dissection: Pre-hospital and in-hospital management

A young pregnant woman (32nd week of gestation) presented with acute chest pain due to right coronary artery dissection (CAD) in a pre-hospital setting. The pre-hospital diagnosis by the ambulance staff of an acute myocardial infarction in the antenatal period based on a 12-lead ECG combined with successful treatment by percutaneous coronary intervention with stenting is novel.

Cardiac troponins as biomarkers of drug- and toxin-induced cardiac toxicity and cardioprotection

Cardiac troponin T and I (cTnT, cTnI) are sensitive biochemical markers of myocardial cell necrosis and have been adopted as the gold standard tests for acute myocardial infarction. Subtle elevations in cTn above the detection limits of the currently available commercial assays confers poor prognosis. These markers are superior to classical enzyme markers of necrosis due to their cardiospecificity. The diagnosis of drug-induced cardiac toxicity using the classical enzymes is problematic due to the high elevations of these markers in skeletal muscle necrosis. cTnT and cTnI are now being adopted as sensitive biomarkers of drug-induced cardiac toxicity.

Early prognostic significance of umbilical cord troponin I in critically ill newborns. Prospective study with a control group

AIM

To determine the value of cord blood cardiac troponin I levels (cTnl) as an early prognostic factor in critically ill newborns, and to compare cord cTnl levels with the prognostic value of the score for neonatal acute physiology (SNAP).

METHODS

Cord arterial samples were collected routinely for blood gas analysis, and cord venous samples for cTnl and cardiac-specific creatine kinase assay. The study group (n=109) comprised critically ill newborns who required mechanical ventilation. The control group (n = 96) comprised newborns who were either completely healthy (n = 48) or were followed in a level I neonatal care unit due to moderate-severity problems.

RESULTS

The critically ill newborns had significantly higher cTnl levels than control babies (median [min-max] 1.4 [0-13] vs. 0 [0-1.8] ng/mL, respectively; P<0.001). In critically ill newborns, non-survivors had significantly higher cTnl levels than survivors (median [min-max] 6.6 [1.3-13.0] vs. 1.3 [0-8.0] ng/mL, respectively; P<0.001). Receiver-operator curve analysis revealed that, compared with SNAP, cTnl was a more sensitive predictor of mortality in critically ill newborns (area under curve=0.96; 95% CI=0.90-1.02).

CONCLUSION

Significantly elevated cord cTnl may be a valuable predictor of mortality in critically ill newborns.

Management of ischaemic heart disease in women of child-bearing age

Ischaemic heart disease is rare in young women but is expected to increase with increasing average age of child bearing. Diagnosis of myocardial ischaemia in this group is complicated by limited data about maternal and fetal safety of the standard diagnostic tests routinely used in other patients. Management of these patients remains difficult, as many standard treatments, such as beta-blockers and angiotensin converting enzyme inhibitors are pregnancy category C or D, and there is little experience with many of the newer treatments such as coronary artery stenting, clopidogrel and glycoprotein IIb/IIIa inhibitors in pregnancy. An interesting case of a woman, who had an acute myocardial infarction treated with thrombolysis and coronary artery stenting, and who subsequently became pregnant, is reported here, and other published reports regarding the management of coronary artery disease, both acute and chronic, in pregnant women are explored.

Concentrations of cardiac troponin T in neonates with and without respiratory distress

AIMS

To establish a practical postnatal reference range for cardiac troponin T in neonates and to investigate concentrations in neonates with respiratory distress.

METHODS

Prospective investigation in a tertiary neonatal unit, recruiting infants with and without respiratory distress (sick and healthy infants respectively). Concentrations of cardiac troponin T were compared between sick and healthy infants, accounting for confounding variables.

RESULTS

A total of 162 neonates (113 healthy and 49 sick infants) had samples taken. The median (interquartile range) cardiac troponin T concentration in the healthy infants was 0.025 (0.01-0.062) ng/ml, and the 95th centile was 0.153 ng/ml. There were no significant relations between cardiac troponin T and various variables. The median (interquartile range) cardiac troponin T concentration in the sick infants was 0.159 (0.075-0.308) ng/ml. This was significantly higher (p < 0.0001) than in the healthy infants. In a linear regression model, the use of inotropes and oxygen requirement were significant associations independent of other basic and clinical variables in explaining the variation in cardiac troponin T concentrations.

CONCLUSIONS

Cardiac troponin T is detectable in the blood of many healthy neonates, but no relation with important basic and clinical variables was found. Sick infants have significantly higher concentrations than healthy infants. The variations in cardiac troponin T concentration were significantly associated with oxygen requirement or the use of inotropic support in a regression model. Cardiac troponin T may be a useful marker of neonatal and cardiorespiratory morbidity.

Maternal and fetal side effects of tocolysis using transdermal nitroglycerin or intravenous fenoterol combined with magnesium sulfate

OBJECTIVE

To compare the maternal and fetal side effects of transdermal nitroglycerin and intravenous fenoterol combined with magnesium sulfate in a prospective randomised study.

STUDY DESIGN

Fifty pregnant women between 27 and 35 weeks of gestation with preterm labour were treated with either nitroglycerin (0.4-0.8 mg/h) or fenoterol (60 - 120 microg/h). Outcome parameters were (1) the effects on fetal and maternal heart frequency (FHF/MHF) and blood pressure, and (2) subjective experiences of adverse effects assessed by utilising a questionnaire.

RESULTS

In the fenoterol group, elevated mean MHF, FHF and systolic blood pressure were recorded compared to nitroglycerin. Fewer maternal side effects were reported in the nitroglycerin group. Palpitations (82%), tremor (68%) and restlessness (64%) were most common in the fenoterol group (two drop-outs), whereas nitroglycerin caused headaches in 71% of the cases (four drop-outs).

CONCLUSION

Transdermal nitroglycerin appears to be a safe therapy for the mother and fetus and is a promising new option for the treatment of preterm labour.

Test strategies for the detection of myocardial damage

In the space of half a century, cardiac marker testing has advanced incrementally from enzymes present in nearly all tissues to proteins having remarkable specificity for myocardium. Markers with other desirable properties, such as earlier release, have also been introduced and others may be anticipated, although a single perfect marker is not on the horizon. Optimum application of these new markers still requires improved robustness and harmonization of commercial assays, and continuing insights in the pathophysiology of acute coronary syndromes. As these advances occur, future testing will likely focus more on therapeutic decisions than on arbitrary diagnostic classifications.

Cardiac troponin T in cord blood

BACKGROUND

Perinatal asphyxia is associated with cardiac dysfunction. This may be secondary to myocardial ischaemia. Cardiac troponin T is the ideal marker for myocardial necrosis. Elevated levels in cord blood may be associated with intrauterine hypoxia and increased perinatal morbidity.

AIMS

To establish an upper limit of normal for cardiac troponin T concentration in the cord blood of infants. Relations between cardiac troponin T levels and other variables were investigated.

METHODS

Cord blood samples were collected from 242 infants and analysed. Data on gestation, birth weight, sex, Apgar scores, respiratory status, and mode of delivery were recorded.

RESULTS

A total of 242 samples were collected, and 215 samples from infants without respiratory distress were used to establish the 95th percentile of 0.050 ng/ml. The gestation of these infants ranged from 31 to 42 weeks and birth weight ranged from 1.4 to 5 kg. There were no relations between cardiac troponin T levels and the other variables in these healthy infants. Twenty seven infants developed respiratory symptoms requiring oxygen and/or ventilation. These infants had significantly higher cord cardiac troponin T levels than their healthy counterparts (median (interquartile range) 0.031 (0.010-0.084) v 0.010 (0.010-0.014) ng/ml respectively; p < 0.001).

CONCLUSIONS

Cardiac troponin T levels in the cord blood are unaffected by gestation, birth weight, sex, or mode of delivery. Infants with respiratory distress had significantly higher cord cardiac troponin T levels, suggesting that cardiac troponin T may be a useful marker for myocardial damage in neonates.