High-sensitivity cardiac troponin assays and unstable angina

The term unstable angina has been conventionally applied to patients with myocardial ischemia without myocardial necrosis. However, while the clinical context has remained constant over time, the biomarkers of myocardial injury and acute myocardial infarction have evolved. High-sensitivity cardiac troponin assays have several key analytical differences from prior cardiac troponin assay generations, which may alter the diagnosis and frequency of unstable angina, as well as affect our understanding of previously developed risk stratification strategies. This document reviews the current challenges in regards to unstable angina when using high-sensitivity cardiac troponin I and T assays.

Incidence of Undetectable, Measurable, and Increased Cardiac Troponin I Concentrations Above the 99th Percentile Using a High-Sensitivity vs a Contemporary Assay in Patients Presenting to the Emergency Department

INTRODUCTION

We compared the incidence of undetectable [below the limit of detection (LoD)], measurable (LoD to 99th percentile), and increased cardiac troponin I (cTnI) concentrations above the 99th percentile between Abbott high-sensitivity cTnI (hs-cTnI) and contemporary cTnI assays in a US emergency department population.

METHODS

Patients (n = 2100) presenting to the emergency department who had serial cTnI (0, 3, 6, 9 h) measurements ordered on clinical indication were enrolled. Contemporary cTnI [Abbott Architect used clinically; 99th percentile: 0.030 μg/L (30 ng/L)] and hs-cTnI [Abbott investigational; sex-specific 99th percentiles: female (F) 16 ng/L, male (M) 34 ng/L] assays simultaneously measured fresh EDTA plasma.

RESULTS

The hs-cTnI assay measured fewer undetectable cTnI concentrations compared to the contemporary cTnI assay across baseline (F: 31% vs 47%, M: 22% vs 40%) and serial (F: 21% vs 46%; M: 19% vs 54%) measurements. Conversely, the proportion of measurable cTnI concentrations was higher using hs-cTnI compared to contemporary cTnI assay across both baseline (F: 46% vs 31%; M: 60% vs 33%) and serial (F: 48% vs 28%; M: 83% vs 40%) measurements. The overall proportion of patients with increased cTnI concentrations above the 99th percentile was not significantly different between the contemporary (31%) and hs-cTnI (26%) assays (P = 0.09).

CONCLUSIONS

In patients presenting to the emergency department, the use of the Abbott hs-cTnI assay provides clinicians with more numeric cTnI concentrations. This occurs via a shift from results below the LoD to those between the LoD and the 99th percentile and does not increase in the number of cTnI concentrations above the 99th percentile.

Present and Future of Cardiac Troponin in Clinical Practice: A Paradigm Shift to High-Sensitivity Assays

Despite its wide utilization and central role in the evaluation of patients with potential ischemic symptoms, misconceptions and confusion about cardiac troponin (cTn) prevail. The implementation of high-sensitivity (hs) cTn assays in clinical practice has multiple potential advantages provided there is an education process tied to the introduction of these assays that emphasizes the appropriate utilization of the test. Several diagnostic strategies have been explored with hs-cTn assays, including the use of undetectable values, accelerated serial hs-cTn sampling, hs-cTn measurements in combination with a clinical-risk score, and the use of a single hs-cTn measurement with a concentration threshold tailored to meet a clinical need. In this document we discuss basic concepts that should facilitate the integration of hs-cTn assays into clinical care in years to come.

Epidemiology and risk factors for nosocomial bloodstream infections in solid organ transplants over a 10-year period

BACKGROUND

Bloodstream infections (BSIs) are a leading cause of morbidity and mortality in solid organ transplantation (SOT). We sought to determine the types of nosocomial BSIs and risk factors for them in SOT.

METHODS

Prospectively collected databases of all SOT and nosocomial BSIs occurring at our institution for a 10-year period were reviewed.

RESULTS

From 2003-2012, we observed 157 nosocomial BSI episodes in 2257 SOTs, the majority of which were caused by staphylococci and enterococci (67.5%). The most common sources of BSI were central line, organ space, respiratory, and gastrointestinal. Kidney transplant patients had the lowest risk of acquiring a BSI compared with other SOT types. Lung transplant patients were at increased risk of methicillin-resistant Staphylococcus aureus BSI and heart transplant patients were at increased risk of a Candida albicans BSI, when compared to other organ transplant types. When coagulase-negative Staphylococcus (CoNS) or C. albicans was isolated, the central line was most often the source. The implementation of central-line bundles during the study period correlated temporally with a decreased rate of CoNS BSI. Over the 10-year period, vancomycin-resistant enterococci became the most common enterococcal BSI. Donor-positive cytomegalovirus status was associated with an increased risk of BSI, when compared to donor-negative patients.

CONCLUSIONS

This study demonstrates the common sources, risk factors, and causative organisms of BSI, which can guide empiric antibiotic choices, and highlights areas where preventative interventions could be targeted to prevent nosocomial BSI in SOT.

Dogs and Monsters: Moral Status Claims in the Fiction of Dean Koontz

This article explores conceptions of moral status in the work of American thriller author Dean Koontz. It begins by examining some of the general theories of moral status used by philosophers to determine whether particular entities have moral status. This includes both uni-criterial theories and multi-criterial theories of moral status. After this examination, the article argues for exploring bioethics conceptions in popular fiction. Popular fiction is considered a rich source for analysis because it provides not only a good approximation of the beliefs of ordinary members of the moral community, but also explores important issues in a context where ordinary individuals are likely to encounter them. Following on from this, the article then explores theories of moral status in the context of Koontz's novels. In particular, the article focuses on the novel Watchers and Koontz's Frankenstein series. Through these works, Koontz indicates that entities have moral status for a variety of reasons and thus presumably, he is a proponent of multi-criterial theories of moral status. The article concludes with an examination of what this might mean for our understanding of moral status claims generally.

High-sensitivity cardiac troponin I at presentation in patients with suspected acute coronary syndrome: a cohort study

BACKGROUND

Suspected acute coronary syndrome is the commonest reason for emergency admission to hospital and is a large burden on health-care resources. Strategies to identify low-risk patients suitable for immediate discharge would have major benefits.

METHODS

We did a prospective cohort study of 6304 consecutively enrolled patients with suspected acute coronary syndrome presenting to four secondary and tertiary care hospitals in Scotland. We measured plasma troponin concentrations at presentation using a high-sensitivity cardiac troponin I assay. In derivation and validation cohorts, we evaluated the negative predictive value of a range of troponin concentrations for the primary outcome of index myocardial infarction, or subsequent myocardial infarction or cardiac death at 30 days. This trial is registered with ClinicalTrials.gov (number NCT01852123).

FINDINGS

782 (16%) of 4870 patients in the derivation cohort had index myocardial infarction, with a further 32 (1%) re-presenting with myocardial infarction and 75 (2%) cardiac deaths at 30 days. In patients without myocardial infarction at presentation, troponin concentrations were less than 5 ng/L in 2311 (61%) of 3799 patients, with a negative predictive value of 99·6% (95% CI 99·3-99·8) for the primary outcome. The negative predictive value was consistent across groups stratified by age, sex, risk factors, and previous cardiovascular disease. In two independent validation cohorts, troponin concentrations were less than 5 ng/L in 594 (56%) of 1061 patients, with an overall negative predictive value of 99·4% (98·8-99·9). At 1 year, these patients had a lower risk of myocardial infarction and cardiac death than did those with a troponin concentration of 5 ng/L or more (0·6% vs 3·3%; adjusted hazard ratio 0·41, 95% CI 0·21-0·80; p<0·0001).

INTERPRETATION

Low plasma troponin concentrations identify two-thirds of patients at very low risk of cardiac events who could be discharged from hospital. Implementation of this approach could substantially reduce hospital admissions and have major benefits for both patients and health-care providers.

FUNDING

British Heart Foundation and Chief Scientist Office (Scotland).

Validation of the modified Sgarbossa criteria for acute coronary occlusion in the setting of left bundle branch block: A retrospective case-control study

BACKGROUND

The modified Sgarbossa criteria were proposed in a derivation study to be superior to the original criteria for diagnosing acute coronary occlusion (ACO) in left bundle branch block (LBBB). The new rule replaces the third criterion (5 mm of excessively discordant ST elevation [STE]) with a proportion (at least 1 mm STE and STE/S wave ≤-0.25). We sought to validate the modified criteria.

METHODS

This retrospective case-control study was performed by chart review in 2 tertiary care center emergency departments (EDs) and 1 regional referral center. A billing database was used at 1 site to identify all ED patients with LBBB and ischemic symptoms between May 2009 and June 2012. In addition, all 3 sites identified LBBB ACO patients who underwent emergent catheterization. We measured QRS amplitude and J-point deviation in all leads, blinded to outcomes. Acute coronary occlusion was determined by angiographic findings and cardiac biomarker levels, which were collected blinded to electrocardiograms. Diagnostic statistics of each rule were calculated and compared using McNemar's test.

RESULTS

Our consecutive cohort search identified 258 patients: 9 had ACO, and 249 were controls. Among the 3 sites, an additional 36 cases of ACO were identified, for a total of 45 ACO cases and 249 controls. The modified criteria were significantly more sensitive than the original weighted criteria (80% vs 49%, P < .001) and unweighted criteria (80% vs 56%, P < .001). Specificity of the modified criteria was not statistically different from the original weighted criteria (99% vs 100%, P = .5) but was significantly greater than the original unweighted criteria (99% vs 94%, P = .004).

CONCLUSIONS

The modified Sgarbossa criteria were superior to the original criteria for identifying ACO in LBBB.

"Persistent Juvenile" T-Wave Pattern May Not Be Persistent: Case Series and Literature Review

BACKGROUND

T-wave inversions (TWI) can signify serious pathology, but may also represent a benign variant. One such variant has been termed the "persistent juvenile" T-wave pattern (PJTWP). It is characterized by TWI in the right precordium, and has been understood to represent an arrested stage of the normal electrocardiographic evolution from childhood.

CASE REPORT

A series of four African-American (AA) women, ages 20 to 43 years, presented to the Emergency Department, and were found to have right precordial TWI that was absent on prior electrocardiograms. The diagnostic evaluation did not reveal acute cardiopulmonary causes for these new TWIs. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: The "persistent" juvenile pattern may not be actually persistent in the individual patient. In an appropriate patient, such as a young AA woman, where acute cardiopulmonary disease has been reasonably ruled out, the finding of new right precordial TWI should not preclude the diagnosis of PJTWP.

A bridge too far: individualised claims of conscience

This article will explore the role of conscience in cases which are not subject to a predictable, generalisable rule-based conscientious objection. These claims arise in cases where doctors, who might have previously provided the treatment at issue, determine that the specific facts of a case mean that they cannot morally provide treatment. In legal cases, the courts have tended to act as if these conscience refusals are part of the best interests analysis. They claim that the treatment, as requested, simply is not in the best interests of the patient. However, the courts have used this analysis even when it appears clear that the refusal of treatment is not in what the patient thinks is his or her best interests. Indeed, in recent cases such as Aintree v James, the court has made it clear that determining what is in the best interests of patients usually relies more on the advice of healthcare professionals than it does on the patient's views. It is not, then, about what patients think they need or want, but what doctors and other medical staff think they can morally provide under the circumstances. This article will explore how re-conceptualising these sorts of claims as ones about conscience provides a more stable footing for understanding the legal and ethical issues which are of importance to the courts and what this might mean for these sorts of decisions in the future.

Diagnosis of Type 1 and Type 2 Myocardial Infarction Using a High-Sensitivity Cardiac Troponin I Assay with Sex-Specific 99th Percentiles Based on the Third Universal Definition of Myocardial Infarction Classification System

BACKGROUND

The frequency and characteristics of myocardial infarction (MI) subtypes per the Third Universal Definition of MI (TUDMI) classification system using high-sensitivity (hs) cardiac troponin assays with sex-specific cutoffs is not well known. We sought to describe the diagnostic characteristics of type 1 (T1MI) and type 2 (T2MI) MI using an hs–cardiac troponin I (hs-cTnI) assay with sex-specific cutoffs.

METHODS

A total of 310 consecutive patients with serial cTnI measurements obtained on clinical indication were studied with contemporary and hs-cTnI assays. Ninety-ninth percentile sex-specific upper reference limits (URLs) for the hs-cTnI assay were 16 ng/L for females and 34 ng/L for males. The TUDMI consensus recommendations were used to define and adjudicate MI based on each URL.

RESULTS

A total of 127 (41%) patients had at least 1 hs-cTnI exceeding the sex-specific 99th percentiles, whereas 183 (59%) had hs-cTnI within the reference interval. Females had more myocardial injury related to supply/demand ischemia than males (39% vs 18%, P = 0.01), whereas males had more multifactorial or indeterminate injury (52% vs 33%, P = 0.05). By hs-cTnI, there were 32 (10%) acute MIs, among which 10 (3%) were T1MI and 22 (7%) were T2MI. T2MI represented 69% (22 out of 32) of all acute MIs, whereas T1MI represented 31% (10 out of 32). Ninety-five patients (31%) had an increased hs-cTnI above the 99th percentile but did not meet criteria for acute MI. The most common triggers for T2MI were tachyarrhythmias, hypotension/shock, and hypertension. By contemporary cTnI, more MIs (14 T1MI and 29 T2MI) were diagnosed. By contemporary cTnI, there were 43 MIs, 14 T1MI, and 29 T2MI.

CONCLUSIONS

Fewer MI diagnoses were found with the hs-cTnI assay, contrary to the commonly accepted idea that hs-cTnI will lead to excessive false-positive diagnoses.

Electronic Medical Record–Based Performance Improvement Project to Document and Reduce Excessive Cardiac Troponin Testing

BACKGROUND

We assessed the utilization rationale behind provider ordering of cardiac troponin I (cTnI) testing for the diagnosis of myocardial infarction after implementation of a hospital-wide serial order protocol.

METHODS

During 2 months in 2013, any request for additional cTnI testing within 30 days of the initial serial cTnI order prompted an electronic health record best practice alert (BPA), which included clinical decision support that could be bypassed by giving a clinical indication. cTnI orders were not limited (timing, number), and upon BPA, trigger data was collected for clinical indications and actions, patient stay (duration, location), International Classification of Diseases, Revision 9 diagnosis, cTnI orders, and timing of cTnI measurements.

RESULTS

The BPA was triggered 1477 times by 423 providers who cared for 702 patients. There were a mean of 3.6 cTnI results per patient, 2.1 BPAs per patient, and 1.2 visits per patient. Providers (42% of whom were residents) acknowledged and overrode the BPA 97% of the time. In response to the BPA, 65% of providers selected a prepared rationale: 64% acute coronary syndrome/ST-elevation myocardial infarction/non–ST-elevation myocardial infarction; 30% demand ischemia; and 6% non-ACS myocardial necrosis. Of the remaining 35% of providers, 71% listed no rationale for their additional cTnI orders. Of patients with a BPA, 93% had non–ACS-related primary International Classification of Diseases, Revision 9 diagnosis, and 58% of the time, patients' cTnI results never increased during their stay. In 53% of cases, BPAs were generated by a request for an additional cTnI series when &lt;2 results were available.

CONCLUSIONS

Providers largely ignored the BPA that warned of potential overutilization of cTnI testing independent of diagnosis, including ACS.

Preventing risk for significant behavior problems through a cognitive-behavioral intervention: effects of the tools for getting along curriculum at one-year follow-up

Efficient and effective social-emotional learning programs increase the likelihood of success in school for all students, and particularly for those who may develop emotional or behavior problems. In this study, we followed a sub-sample of students 1 year after their participation in a randomized controlled trial of the effects of the Tools for Getting Along (TFGA) curriculum. TFGA is a universally delivered, preventive cognitive-behavioral curricular intervention designed to improve upper elementary school students' emotional and behavioral self-regulation. To determine effects at 1-year follow-up, we assessed 720 out of the 1,296 original students across TFGA and control conditions on measures of curricular knowledge, teacher-rated executive function and behavior, and student-reported anger and social problem solving. Findings indicated a continued positive effect on curricular knowledge for students taught TFGA relative to controls. We also found significant pretest by condition interaction effects on teacher reports of skills associated with executive function, including inhibitory control and shift (cognitive flexibility), and on teacher reported internalizing and externalizing behavior. Specifically, students with poorer scores on these measures at pretest benefited from TFGA at follow-up relative to comparable students in the control condition. Finally, we found marginally significant pretest by condition interaction effects on proactive aggression, outward expressions of anger, and the executive function related skills of initiating activities and using working memory. Counter to expectations, we found negative TFGA effects on student-reported trait anger and anger control.