Kieran M. Daly

Cardiac troponin I in pre‐eclampsia and gestational hypertension

Objective To investigate serum cardiac troponin I, a sensitive marker of cardiac myocyte damage, in normal pregnancy and pregnancies complicated by hypertension with and without significant proteinuria.

False-positive cardiac troponin I in a routine clinical population

We conclude that inaccurate quantification of cTnI is prevalent, but that with further sample manipulation, such false-positive results may be eliminated without significant risk of clearing true-positive results. We recommend repeated serum cTnI estimation in equivocal cases and suggest that similar studies such as ours need to be undertaken to examine the prevalence of spurious positive results for other cardiac troponin assay platforms.

Cardiac troponins in suspected acute coronary syndrome a meta-analysis of published trials

We performed a meta-analysis of published trials to determine the predictive value of cardiac troponin I (cTnI) and T (cTnT) levels for adverse events (death and myocardial infarction) in acute coronary syndrome without ST elevation (ACS). The accumulated odds ratio (OR) for adverse events (30 days) in ACS with elevated cTnI (n = 5,759) and cTnT (n = 5,483) was 4.9 (95% confidence interval, CI, 3.9–6.2) and 4.6 (95% CI 3.8–5.5), respectively. Trials that mandated timed serum sampling (6 or more hours after symptom onset) had an improved predictive value for elevated cTnI (n = 2,807, OR 8.8; 95% CI 5.9–13.2) and cTnT (n = 1,990, OR 8.5; 95% CI 5.9–12.5). In conclusion, cTnI and cTnT provide similar information in ACS. The risk of adverse events is 4-fold higher in patients with suspected ACS and elevated serum cTn. For patients with an elevated timed (6-hour) sample the risk is over 8-fold higher.

Cardiac Troponin I and N-Terminal Pro-Brain Natriuretic Peptide in Umbilical Artery Blood in Relation to Fetal Heart Rate Abnormalities During Labor

Abstract. The use of continuous fetal heart rate (FHR) recordings to monitor fetal well-being during labor is standard clinical practice in developed countries. Little is known about the relationship, if any, that exists between these FHR abnormalities and the fetal cardiac musculature and function. The aim of this study was to investigate umbilical artery serum levels of cardiac troponin I, a sensitive and specific marker of myocardial necrosis, and N-terminal pro-brain natriuretic peptide (pro-BNP), a sensitive marker of left ventricular dysfunction, in relation to FHR abnormalities. Umbilical artery blood samples were taken from 27 cases immediately after delivery of the infant. There was evidence of significant FHR abnormalities in 11 of these cases (group 2) and the FHR recording was normal in 16 cases (group 1). The mean N-terminal pro-BNP level in umbilical artery serum in group 2 was 413 fmol/L (SEM = 85) and in group 1 was 223 fmol/L (SEM = 28)(p= 0.022). There was no significant difference observed in cardiac troponin I levels between the two groups. Umbilical artery serum N-terminal pro-BNP is elevated in association with fetal heart rate abnormality in the late stage of labor. This finding suggests that some degree of cardiac compromise accompanies FHR abnormality.

Amino-terminal pro-brain natriuretic peptide in normal and hypertensive pregnancy.

Objectives: To investigate serum levels of amino-terminal pro-brain natriuretic peptide (Nt pro-BNP) as an index of left-ventricular function in normal pregnancy and pregnancies complicated by hypertension and also to investigate levels in both primigravid and multigravid women. Methods: Women with hypertension in pregnancy (at least two readings of systolic blood pressure > 140 mm Hg and diastolic blood pressure > 90 mm Hg) (n = 24) and normotensive women (n = 42) were included in the study. Serum Nt pro-BNP was measured using an enzyme-linked immunosorbent assay technique. Results: The median serum Nt pro-BNP level in pregnancies complicated by hypertension was 420 fmol/L, which was significantly greater than that measured in samples obtained from normotensive women in pregnancy (340 fmol/L) (p = 0.03). There was a nonsignificant trend toward increased levels in proteinuric as compared to nonproteinuric hypertension in pregnancy. Multigravida had higher Nt pro-BNP levels (n = 26; median Nt pro-BNP = 358 fmol/L) than primigravida (n = 16; median Nt pro-BNP = 278 fmol/L) (p = 0.01) in association with normal pregnancy. Multigravida also demonstrated a dramatic rise in serum Nt pro-BNP levels in association with hypertension in pregnancy (n = 13; median Nt pro-BNP = 572 fmol/L) as compared to normal pregnancy (n = 26; median Nt pro-BNP = 358 fmol/L) (p = 0.009). Conclusion: Serum Nt pro-BNP is elevated in women with hypertensive disorders of pregnancy, indicating elevated left-ventricular filling pressures. Measured serum levels in both normal and hypertensive pregnancy are higher in multigravida than in primigravida.

The role of cardiac troponin I in determining the necessity for exercise electrocardiography in low risk patients with chest pain.

BackgroundAssessment of non-cardiac chest pain places a considerable burden on healthcare resources. The current practice of serial electrocardiographs (ECGs), serum creatinine phosphokinase and by pre-discharge exercise electrocardiography gives an average in-hospital stay of 3.7 days.AimsThis study assess “the use of a sensitive assay for cardiac troponin I (cTnI) to identify a low risk group for whom exercise ECG may not be indicated.MethodNinety-five patients with acute chest pain and with peak cTnI <0.1 ng/ml and a non-diagnostic resting ECG were studied. Patients were divided into two groups. Group one had normal range cTnI (<0.03 ng/ml). Group two had minimal elevation of cTnI (0.03 – 0.099 ng/ml). Average follow-up was 172 days.ResultsNineteen patients had minimal elevation in cTnI of whom five developed significant ST shift on exercise and five had adverse events. No patient with a normal range cTnI had a positive stress test and none suffered an adverse event (p<0.00.1).ConclusionCTnI in the normal range can identify patients with acute chest pain who have a negligible event rate and for whom exercise electrcardiography is not required.

The implantable defibrillator and return to operation of vehicles study

AIMS We sought to characterise driving habits of contemporary implantable cardioverter defibrillator (ICD) patients. METHODS AND RESULTS We performed a multicentre prospective observational study of consecutive ICD recipients. Non-commercial drivers with a valid licence were eligible. Patient and ICD data were recorded. All patients completed an anonymous questionnaire regarding their driving habits. Among 275 patients, 25 (9.1%) stopped driving permanently after ICD implantation. During a mean follow-up of 26.5 ± 4.5 months, 25.3% of patients received an ICD shock (52.5% appropriate). The median time to first shock was 7.0 (2.5, 17.5) months and was not significantly different between primary and secondary ICD patients. However, shocks (36.5 vs. 21.3%, P = 0.027) and recurrent shock episodes (17.5 vs. 6.2%, P = 0.011) were more common in secondary ICD patients. Physician-recommended driving restrictions were not recalled by 37.9% and not followed by 23.0% of patients. Overall, the mean duration of driving abstinence was 2.2 ± 2.9 and 3.6 ± 5.3 months for primary and secondary patients, respectively. Notably, 36.5% of secondary patients drove within 1 month. Eight patients (3.3%) received a shock while driving, five of which resulted in road traffic accidents. The annual risk of a shock while driving was 1.5%. CONCLUSIONS Patient driving behaviour following ICD implantation is variable, with over one-third not remembering and almost one-quarter not adhering to physician-directed driving restrictions. Over one-third of secondary ICD patients drive within 1 month despite physician recommendations. Further studies are required to establish the optimal duration of driving restriction in ICD recipients.

Effect of prolonged nifedipine or captopril therapy on lymphocyte magnesium and potassium levels in hypertension.

The effect of prolonged treatment with calcium channel blockers on potassium and magnesium stores is uncertain. We measured lymphocyte and serum magnesium and potassium in 28 patients treated for hypertension for 6 months with nifedipine or captopril. There was no difference in serum or lymphocyte concentrations in the two groups compared to 45 healthy, normotensive controls. These results suggest that intracellular cation levels are maintained with prolonged therapy with calcium channel blockers.

The provision of secondary cardiac prevention measures in a hospital cardiac clinic population and the relationship to psychological variables

BackgroundImplementing preventive measures in patients with established heart disease is one of the most effective health promotion activities, but there is little research on the relationship between cognition and secondary preventive behaviour.AimTo determine the provision of secondary cardiac prevention measures among patients with established heart disease attending a cardiac outpatient clinic.MethodsThe study was conducted in an outpatient department over a 14-week period in 1999. Management of risk markers was noted from the medical records and lifestyle and psychological variables were self-reported.ResultsOf 294 patients with heart disease, 41% were available for study. Fourteen per cent were current smokers, one-quarter of males and one-third of females had a body mass index (BMI) greater that 30. Almost 90% attend their GP bimonthly, 67% had a normal systolic and 88.3% a normal diastolic pressure, 34% had normal cholesterol levels and 75% were on aspirin. Lifestyle variables were significantly affected by patient cardiac knowledge, sense of control over their heart disease and perceptions of their illness.ConclusionsThese results highlight the potential health gain available to patients with established heart disease. The results also suggest that psychological factors may play a role in patients’ health behaviours.