Chest pain unit concept: rationale and diagnostic strategies

Establishing optimal cutoff values for high-sensitivity cardiac troponin algorithms in risk stratification of acute myocardial infarction

Acute myocardial infarction (AMI) is a leading cause of mortality globally, highlighting the need for timely and accurate diagnostic strategies. Cardiac troponin has been the biomarker of choice for detecting myocardial injury. A dynamic change in concentrations supports the diagnosis of AMI in the setting of evidence of acute myocardial ischemia. The new generation of high-sensitivity cardiac troponin (hs-cTn) assays has significantly improved analytical sensitivity but at the expense of decreased clinical specificity. As a result, sophisticated algorithms are required to differentiate AMI from non-AMI patients. Establishing optimal hs-cTn cutoffs for these algorithms to rule out and rule in AMI has been the subject of intensive investigations. These efforts have evolved from examining the utility of the hs-cTn 99th percentile upper reference limit, comparing the percentage versus absolute delta thresholds, and evaluating the performance of an early European Society of Cardiology-recommended 3 h algorithm, to the development of accelerated 1 h and 2 h algorithms that combine the admission hs-cTn concentrations and absolute delta cutoffs to rule out and rule in AMI. Specific cutoffs for individual confounding factors such as sex, age, and renal insufficiency have also been investigated. At the same time, concerns such as whether the small delta thresholds exceed the analytical and biological variations of hs-cTn assays and whether the algorithms developed in European study populations fit all other patient cohorts have been raised. In addition, the accelerated algorithms leave a substantial number of patients in a non-diagnostic observation zone. How to properly diagnose patients falling in this zone and those presenting with elevated baseline hs-cTn concentrations due to the presence of confounding factors or comorbidities remain open questions. Here we discuss the developments described above, focusing on criteria and underlying considerations for establishing optimal cutoffs. In-depth analyses are provided on the influence of biological variation, analytical imprecision, local AMI rate, and the timing of presentation on the performance metrics of the accelerated hs-cTn algorithms. Developing diagnostic strategies for patients who remain in the observation zone and those presenting with confounding factors are also reviewed.

Diagnostic discrimination of a novel high-sensitivity cardiac troponin I assay and derivation/validation of an assay-specific 0/1h-algorithm

BACKGROUND

We aimed to assess the diagnostic utility of the Dimension EXL LOCI High-Sensitivity Troponin I (hs-cTnI-EXL) assay.

METHODS

This multicenter study included patients with chest discomfort presenting to the emergency department. Diagnoses were centrally and independently adjudicated by two cardiologists using all available clinical information. Adjudication was performed twice including serial measurements of high-sensitivity cardiac troponin (hs-cTn) I-Architect (primary analysis) and serial measurements of hs-cTnT-Elecsys (secondary analysis) in addition to the clinically used (hs)-cTn. The primary objective was to assess and compare the discriminatory performance of hs-cTnI-EXL, hs-cTnI-Architect and hs-cTnT-Elecsys for acute myocardial infarction (MI). Furthermore, we derived and validated a hs-cTnI-EXL-specific 0/1h-algorithm.

RESULTS

Adjudicated MI was the diagnosis in 204/1454 (14%) patients. The area under the receiver operating characteristics curve for hs-cTnI-EXL was 0.94 (95%CI, 0.93-0.96), and comparable to hs-cTnI-Architect (0.95; 95%CI, 0.93-0.96) and hs-cTnT-Elecsys (0.93; 95%CI, 0.91-0.95). In the derivation cohort (n = 813), optimal criteria for rule-out of MI were <9ng/L at presentation (if chest pain onset >3h) or <9ng/L and 0h-1h-change <5ng/L, and for rule-in ≥160ng/L at presentation or 0h-1h-change ≥100ng/L. In the validation cohort (n = 345), these cut-offs ruled-out 56% of patients (negative predictive value 99.5% (95%CI, 97.1-99.9), sensitivity 97.8% (95%CI, 88.7-99.6)), and ruled-in 9% (positive predictive value 83.3% (95%CI, 66.4-92.7), specificity 98.3% (95%CI, 96.1-99.3)). Secondary analyses using adjudication based on hs-cTnT measurements confirmed the findings.

CONCLUSIONS

The overall performance of the hs-cTnI-EXL was comparable to best-validated hs-cTnT/I assays and an assay-specific 0/1h-algorithm safely rules out and accurately rules in acute MI.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov number, NCT00470587.

Initial experience regarding the safety and yield of rest-stress myocardial perfusion imaging in emergency department patients with mildly abnormal high-sensitivity cardiac troponins

BACKGROUND

With high-sensitivity troponin testing, approximately a third of patients presenting to emergency departments (EDs) with suspected acute coronary syndromes will have mildly abnormal values. However, data regarding rest-stress myocardial perfusion imaging (MPI) in these patients are limited. We hypothesize that stress testing is safe and that the yield for detecting myocardial ischemia is associated with risk stratification by the HEART score.

METHODS AND RESULTS

We conducted a retrospective cohort study of consecutive patients referred for rest-stress MPI with mildly abnormal high-sensitivity troponin T (hs-cTn) values. Outcomes were adverse events related to stress MPI, defined as myocardial infarction or ventricular tachyarrhythmia, and the presence of ischemia, defined as a reversible perfusion defect. Among 213 patients, the median age was 67, most were male (61.5%, n = 131), and prior CAD was common (53.5%, n = 114). Myocardial ischemia was present in 13.6% (n = 29), and there were no adverse events attributable to stress MPI. A higher HEART score was associated with myocardial ischemia (Odds Ratio [OR] 1.50, 95% Confidence Interval [CI] 1.08 to 2.08, P = .002).

CONCLUSION

Rest-stress MPI appears safe in patients with mildly abnormal hs-cTn values, and the yield for detecting ischemia is associated with the HEART score, though further validation studies are needed.

A Biomarker Model to Distinguish Types of Myocardial Infarction and Injury

BACKGROUND

Discrimination among patients with type 1 myocardial infarction (T1MI), type 2 myocardial infarction (T2MI), and myocardial injury is difficult.

OBJECTIVES

The aim of this study was to investigate the discriminative value of a 29-biomarker panel in an emergency department setting.

METHODS

Patients presenting with suspected myocardial infarction (MI) were recruited. The final diagnosis in all patients was adjudicated on the basis of the fourth universal definition of MI. A panel of 29 biomarkers was measured, and multivariable logistic regression analysis was used to evaluate the associations of these biomarkers with the diagnosis of MI or myocardial injury. Biomarkers were chosen using backward selection. The model was internally validated using bootstrapping.

RESULTS

Overall, 748 patients were recruited (median age 64 years), of whom 138 had MI (107 T1MI and 31 T2MI) and 221 had myocardial injury. In the multivariable model, 4 biomarkers (apolipoprotein A-II, N-terminal prohormone of brain natriuretic peptide, copeptin, and high-sensitivity cardiac troponin I) remained significant discriminators between T1MI and T2MI. Internal validation of the model showed an area under the curve of 0.82. For discrimination between MI and myocardial injury, 6 biomarkers (adiponectin, N-terminal prohormone of brain natriuretic peptide, pulmonary and activation-regulated chemokine, transthyretin, copeptin, and high-sensitivity troponin I) were selected. Internal validation showed an area under the curve of 0.84.

CONCLUSIONS

Among 29 biomarkers, 7 were identified to be the most relevant discriminators between subtypes of MI or myocardial injury. Regression models based on these biomarkers allowed good discrimination. (Biomarkers in Acute Cardiac Care [BACC]; NCT02355457).

Sex-Specific Outcomes in Patients with Acute Coronary Syndrome

Sex differences in patients with acute coronary syndrome (ACS) are a matter of debate. We investigated sex-specific differences in the incidence, outcomes, and related interventions in patients diagnosed with ACS in Germany over the past decade. All ACS cases from 2005 to 2015 were collected. Procedures and inhospital mortality were assessed by sex. Age-adjusted incidence rates were calculated. In total, 1,366,045 females and 2,431,501 males presenting with ACS were recorded. Females were older than males (73.1 vs. 66.4 years of age), had a longer mean hospital stay (7.7 vs. 6.9 days), and less frequently underwent coronary angiographies (55% vs. 66%) and coronary interventions (35% vs. 47%). The age-adjusted incidence rate of ACS was lower in females than in males, and decreased in both sexes from 2005 to 2015. The age-adjusted inhospital mortality rate was substantially higher in females than in males, but decreased in both sexes over time (in females, from 87 to 71 cases per 1000 person years; in males, from 57 to 51 cases per 1000 person years). In conclusion, we reported sex differences in the incidence, treatment, and outcomes of ACS patients in Germany within the past decade. Women had a substantially higher mortality rate and lower rate of coronary interventions.

Effect of a Multi-Diagnosis Observation Unit on Emergency Department Length of Stay and Inpatient Admission Rate at Two Canadian Hospitals

BACKGROUND

Observation units (OUs) have been shown to reduce emergency department (ED) lengths of stay (LOS) and admissions. Most published studies have been on OUs managing single complaints.

OBJECTIVE

Our aim was to determine whether an OU reduces ED LOS and hospital admission rates for adults with a variety of presenting complaints.

METHODS

We comparatively evaluated two hospitals in British Columbia, Canada (hereafter ED A and ED B) using a pre-post design. Data were extracted from administrative databases. The post-OU cohort included all adults presenting 6 months after OU implementation. The pre-OU cohort included all adults presenting in the same 6-month period 1 year before OU implementation.

RESULTS

There were 109,625 patient visits during the study period. Of the 56,832 visits during the post-OU period (27,512 to ED A and 29,318 to ED B), 1.9% were managed in the OU in ED A and 1.4% in ED B. Implementation was associated with an increase in the median ED LOS at ED A (179.0 min pre vs. 192.0 min post [+13.0 min]; p < 0.001; mean difference -12.5 min, 95% confidence interval [CI] -15.2 to -9.9 min), but no change at ED B (182.0 min pre vs. 182.0 min post; p = 0.55; mean difference +2.0 min, 95% CI -0.7 to +4.7 min). Implementation significantly decreased the hospital admission rate for ED A (17.8% pre to 17.0% post [-0.8%], 95% CI -0.18% to 0.15%; p < 0.05) and did not significantly change the hospital admission rate at ED B (18.9% pre to 18.3% post [-0.6%], 95% CI -1.19% to -0.09%; p = 0.09).

CONCLUSIONS

A multi-diagnosis OU can reduce hospital admission rate in a site-specific manner. In contrast to previous studies, we did not find that an OU reduced ED LOS. Further research is needed to determine whether OUs can reduce ED overcrowding.

Incremental value of exercise echocardiography over exercise electrocardiography in a chest pain unit

BACKGROUND

Limited data are available on the added value of exercise echocardiography (ExEcho) over exercise electrocardiography (ExECG) in patients with suspected acute coronary syndromes (ACS) referred to a chest pain unit. We aimed to assess the incremental value of ExEcho over ExECG in this setting.

METHODS

ExECG and ExEcho were performed in parallel in 1052 patients with suspected ACS, nondiagnostic but interpretable electrocardiograms, and negative serial troponin results. The primary outcome was a composite of coronary death, nonfatal myocardial infarction or unstable angina with angiographic documentation of significant coronary artery disease within 6 months.

RESULTS

The primary outcome occurred in 2/614 patients (0.3%) with both negative ExECG and ExEcho, 3/60 (5%) with positive ExECG and negative ExEcho, 73/135 (54.1%) with negative ExECG and positive ExEcho, 106/136 (77.9%) with both positive ExECG and ExEcho, and 8/107 (7.5%) with inconclusive results. The addition of ExEcho data to a model based on clinical and ExECG data significantly increased the c statistic from 0.898 to 0.968 (change +0.070, 95% confidence interval 0.052-0.092), with a continuous net reclassification improvement of 1.56 and an integrated discrimination improvement of 22% (p<0.001). Decision curve analysis showed that a strategy of referral to coronary angiography based on ExEcho was associated with the highest net benefit and with the largest reduction in unnecessary coronary angiographies.

CONCLUSION

ExEcho provides significant incremental prognostic information and higher net clinical benefit than a strategy based on ExECG in patients referred to a chest pain unit for suspected ACS and negative troponin levels.

Gender disparities in stress test utilization in chest pain unit patients based upon the ordering physician's gender

OBJECTIVE

Physicians' gender may impact test utilization in the diagnosis of acute cardiovascular disease. We sought to determine if physician gender affected stress test utilization by patient gender in a low-risk chest pain observation unit.

METHODS

This was a retrospective consecutive cohort study of patients admitted to a chest pain unit in a large volume academic urban emergency department (ED). Inclusion criteria were age>18, American Heart Association low-to-intermediate risk, electrocardiogram nondiagnostic for acute coronary syndrome, and negative initial troponin I. Exclusion criteria were age>75 with a history of coronary artery disease, active comorbid medical problems, or inability to obtain stress testing in the ED for any reason. T-tests were used for univariate comparisons and logistic regression was used to estimate odds ratios (ORs) for receiving testing based on physician gender, controlling for race, insurance, and Thrombolysis In Myocardial Infarction (TIMI) score.

RESULTS

Three thousand eight hundred and seventy-three index visits were enrolled during a 2.5-year period. Mean age was 53±20, 55% (95% CI, 53-56%) were female. There was no difference in overall stress utilization based upon physician gender (P=0.28). However, after controlling for other variables, male physicians had significantly lower odds of stress testing female patients (ORM, 0.82; 95% CI, 0.68-0.99), whereas no difference was found in female physicians (ORF, 0.80; 95% CI, 0.57-1.14).

CONCLUSIONS

Male physicians appear less likely to utilize stress testing in female patients even after controlling for objective clinical variables, including TIMI score. Although adverse outcomes are uncommon in this patient cohort, further investigation into provider-specific practice patterns based on patient gender is necessary.

Criteria of the German Society of Cardiology for the establishment of chest pain units: update 2014

Since 2008, the German Cardiac Society (DGK) has been establishing a network of certified chest pain units (CPUs). The goal of CPUs was and is to carry out differential diagnostics of acute or newly occurring chest pain of undetermined origin in a rapid and goal-oriented manner and to take immediate therapeutic measures. The basis for the previous certification process was criteria that have been established and published by the task force on CPUs. These criteria regulate the spatial and technical requirements and determine diagnostic and therapeutic strategies in patients with chest pain. Furthermore, the requirements for the organization of CPUs and the training requirements for the staff of a CPU are defined. The certification process is carried out by the DGK; currently, 225 CPUs are certified and 139 CPUs have been recertified after running for a period of 3 years. The certification criteria have now been revised and updated according to new guidelines.

The association between pretest probability of coronary artery disease and stress test utilization and outcomes in a chest pain observation unit

OBJECTIVES

Cardiology consensus guidelines recommend use of the Diamond and Forrester (D&F) score to augment the decision to pursue stress testing. However, recent work has reported no association between pretest probability of coronary artery disease (CAD) as measured by D&F and physician discretion in stress test utilization for inpatients. The author hypothesized that D&F pretest probability would predict the likelihood of acute coronary syndrome (ACS) and a positive stress test and that there would be limited yield to diagnostic testing of patients categorized as low pretest probability by D&F score who are admitted to a chest pain observation unit (CPU).

METHODS

This was a prospective observational cohort study of consecutively admitted CPU patients in a large-volume academic urban emergency department (ED). Cardiologists rounded on all patients and stress test utilization was driven by their recommendations. Inclusion criteria were as follows: age>18 years, American Heart Association (AHA) low/intermediate risk, nondynamic electrocardiograms (ECGs), and normal initial troponin I. Exclusion criteria were as follows: age older than 75 years with a history of CAD. A D&F score for likelihood of CAD was calculated on each patient independent of patient care. Based on the D&F score, patients were assigned a priori to low-, intermediate-, and high-risk groups (<10, 10 to 90, and >90%, respectively). ACS was defined by ischemia on stress test, coronary artery occlusion of ≥70% in at least one vessel, or elevations in troponin I consistent with consensus guidelines. A true-positive stress test was defined by evidence of reversible ischemia and subsequent angiographic evidence of critical stenosis or a discharge diagnosis of ACS. An estimated 3,500 patients would be necessary to have 1% precision around a potential 0.3% event rate in low-pretest-probability patients. Categorical comparisons were made using Pearson chi-square testing.

RESULTS

A total of 3,552 patients with index visits were enrolled over a 29-month period. The mean (±standard deviation [SD]) age was 51.3 (±9.3) years. Forty-nine percent of patients received stress testing. Pretest probability based on D&F score was associated with stress test utilization (p<0.01), risk of ACS (p<0.01), and true-positive stress tests (p=0.03). No patients with low pretest probability were subsequently diagnosed with ACS (95% CI=0 to 0.66%) or had a true-positive stress test (95% CI=0 to 1.6%).

CONCLUSIONS

Physician discretionary decision-making regarding stress test use is associated with pretest probability of CAD. However, based on the D&F score, low-pretest-probability patients who meet CPU admission criteria are very unlikely to have a true-positive stress test or eventually receive a diagnosis of ACS, such that observation and stress test utilization may be obviated.

Is it prime time for "rapid comprehensive cardiopulmonary imaging" in the emergency department?

Reducing hospital admissions through improved risk stratification of patients with potential acute coronary syndrome represents a critical focus for reducing health care expenditure. Coronary computed tomographic angiography (CTA) has been used with increasing frequency as part of the evaluation of chest pain in the Emergency Department. In the appropriate group of patients at low to intermediate risk CTA appears to be an excellent evaluation strategy, safely and efficiently allowing for the rapid discharge of patients home.

The evolution of chest pain pathways

Patients presenting to the emergency department with chest pain require prompt identification and referral, as early treatment of patients with an acute coronary syndrome (ACS) is crucial to decrease morbidity and mortality (Steurer et al, Emerg Med J. 2010;27:896-902). Although rule-in ACS is critical and time dependant, other difficulties arise during the rule-out ACS process (Steurer et al, Emerg Med J. 2010;27:896-902). Inappropriate discharge of patients with misdiagnosed acute myocardial infarction is associated with significant morbidity and mortality. Concerns relating to inappropriate discharge result in readmission with resultant lengthy hospital stays, high costs, and contribute to overcrowding and bed block (Amsterdam et al, J Am Coll Cardiol. 2002;40:251-256; Cardiol Clin. 2005;23:503-516; Furtado et al, Emerg Med. In press; Karlson, Am J Cardiol. 1991;68:171-175; Ng et al, Am J Cardiol. 2001;88:611-617; Ramakrishna et al, Mayo Clin Proc. 2005;80:322-329; Stowers, Crit Pathw Cardiol. 2003;2:88-94). The challenge of chest pain diagnosis has led to a number of associated problems within the health care system. The growing need for improvements in consistency of patient care, resource efficiency, and quality of patient healthcare has led to the development of chest pain pathways (Erhardt et al, Eur Heart J. 2002;23:1153-1176). The development and implementation of chest pain pathways is not without difficulties. These may arise from differences in the management approaches of health practitioners, poor adherence to guidelines, and concerns for costs. New procedures such as new cardiac injury markers, stress testing, and specialized chest pain units have led to a reduction in admission rates and length of stay, reduced costs, and a reduction of inappropriate discharge of patients with ischemic heart disease.

Use of saliva-based nano-biochip tests for acute myocardial infarction at the point of care: a feasibility study

BACKGROUND

For adults with chest pain, the electrocardiogram (ECG) and measures of serum biomarkers are used to screen and diagnose myocardial necrosis. These measurements require time that can delay therapy and affect prognosis. Our objective was to investigate the feasibility and utility of saliva as an alternative diagnostic fluid for identifying biomarkers of acute myocardial infarction (AMI).

METHODS

We used Luminex and lab-on-a-chip methods to assay 21 proteins in serum and unstimulated whole saliva procured from 41 AMI patients within 48 h of chest pain onset and from 43 apparently healthy controls. Data were analyzed by use of logistic regression and area under curve (AUC) for ROC analysis to evaluate the diagnostic utility of each biomarker, or combinations of biomarkers, in screening for AMI.

RESULTS

Both established and novel cardiac biomarkers demonstrated significant differences in concentrations between patients with AMI and controls without AMI. The saliva-based biomarker panel of C-reactive protein, myoglobin, and myeloperoxidase exhibited significant diagnostic capability (AUC = 0.85, P < 0.0001) and in conjunction with ECG yielded strong screening capacity for AMI (AUC = 0.96) comparable to that of the panel (brain natriuretic peptide, troponin-I, creatine kinase-MB, myoglobin; AUC = 0.98) and far exceeded the screening capacity of ECG alone (AUC approximately 0.6). En route to translating these findings to clinical practice, we adapted these unstimulated whole saliva tests to a novel lab-on-a-chip platform for proof-of-principle screens for AMI.

CONCLUSIONS

Complementary to ECG, saliva-based tests within lab-on-a-chip systems may provide a convenient and rapid screening method for cardiac events in prehospital stages for AMI patients.

An analysis of the Association of Society of Chest Pain Centers Accreditation to American College of Cardiology/American Heart Association non-ST-segment elevation myocardial infarction guideline adherence

STUDY OBJECTIVE

Since 2003, the Society of Chest Pain Centers (SCPC) has provided hospital accreditation for acute coronary syndrome care processes. Our objective is to evaluate the association between SCPC accreditation and adherence to the American College of Cardiology/American Heart Association (ACC/AHA) evidence-based guidelines for non-ST-segment elevation myocardial infarction (NSTEMI). The secondary objective is to describe the clinical outcomes and the association with accreditation.

METHODS

We conducted a secondary analysis of data from patients with NSTEMI enrolled in the Can Rapid Risk Stratification of Unstable Angina Patients Suppress Adverse Outcomes With Early Implementation of the ACC/AHA Guidelines (CRUSADE) quality improvement initiative in 2005. The analysis explored differences between SCPC-accredited and nonaccredited hospitals in evidence-based therapy given within the first 24 hours (including aspirin, beta-blocker, glycoprotein IIb/IIIa inhibitors, heparin, and ECG within 10 minutes).

RESULTS

Of 33,238 patients treated at 21 accredited hospitals and 323 nonaccredited hospitals, those at SCPC-accredited centers (n=3,059) were more likely to receive aspirin (98.1% versus 95.8%; odds ratio [OR] 1.73; 95% confidence interval [CI] 1.06 to 2.83) and beta-blockers (93.4% versus 90.6%; OR 1.68; 95% CI 1.04 to 2.70) within 24 hours than patients at non-SCPC-accredited centers (n=30,179). No difference was observed in obtaining a timely ECG (40.4% versus 35.2%; OR 1.28; 95% CI 0.98 to 1.67), administering a glycoprotein IIb/IIIa inhibitor (OR 1.30; 95% CI 0.93 to 1.80), or administering heparin (OR 1.12; 95% CI 0.74 to 1.70). Also, there was no significant difference in risk-adjusted mortality for patients treated at SCPC hospitals versus nonaccredited hospitals (3.4% versus 3.5%; adjusted OR 1.17; 95% CI 0.88 to 1.55).

CONCLUSION

SCPC-accredited hospitals had higher NSTEMI ACC/AHA evidence-based guideline adherence in the first 24 hours of care on 2 of the 5 measures. No difference in outcomes was observed. Further studies are needed to better understand the association between SCPC accreditation and improved care for patients with acute coronary syndrome.

Evaluation of patients with methamphetamine- and cocaine-related chest pain in a chest pain observation unit

OBJECTIVE

Risk of acute coronary events in patients with methamphetamine and cocaine intoxication has been described. Little is known about the need for additional evaluation in these patients who do not have evidence of myocardial infarction after the initial emergency department evaluation. We herein describe our experience with these patients in a chest pain unit (CPU) and the rate of cardiac-related chest pain in this group.

METHODS

Retrospective analysis of patients evaluated in our CPU from January 1, 2000 to December 16, 2004 with a history of chest pain. Patients who had a positive urine toxicologic screen for methamphetamine or cocaine were included. No patients had ECG or cardiac injury marker evidence of myocardial infarction or ischemia during the initial emergency department evaluation. A diagnosis of cardiac-related chest pain was based upon positive diagnostic testing (exercise stress testing, nuclear perfusion imaging, stress echocardiography, or coronary artery stenosis >70%).

RESULTS

During the study period, 4568 patients were evaluated in the CPU. A total of 1690 (37%) of patients admitted to the CPU underwent urine toxicologic testing. The result of urine toxicologic test was positive for cocaine or methamphetamine in 224 (5%). In the 2871 patients who underwent diagnostic testing for coronary artery disease (CAD), 401 (14%) were found to have positive results. There was no difference in the prevalence of CAD between those with positive result for toxicology screens (26/156, 17%) and those without (375/2715, 13%, RR 1.2, 95% CI 0.8-1.7).

CONCLUSION

These findings suggest a relatively high rate of CAD in patients with methamphetamine and cocaine use evaluated in a CPU.

New methods for improved evaluation of patients with suspected acute coronary syndrome in the emergency department

This paper aims to identify and review new and unproven emergency department (ED) methods for improved evaluation in cases of suspected acute coronary syndrome (ACS). Systematic news coverage through PubMed from 2000 to 2006 identified papers on new methods for ED assessment of patients with suspected ACS. Articles found described decision support models, new ECG methods, new biomarkers and point-of-care testing, cardiac imaging, immediate exercise tests and the chest pain unit concept. None of these new methods is likely to be the perfect solution, and the best strategy today is therefore a combination of modern methods, where the optimal protocol depends on local resources and expertise. With a suitable combination of new methods, it is likely that more patients can be managed as outpatients, that length of stay can be shortened for those admitted, and that some patients with ACS can get earlier treatment.

Prolonged Emergency Department Stays of Non–ST-Segment-Elevation Myocardial Infarction Patients Are Associated With Worse Adherence to the American College of Cardiology/American Heart Association Guidelines for Management and Increased Adverse Events

STUDY OBJECTIVE

We evaluate the association of emergency department (ED) length of stay with use of guideline-recommended therapies for acute treatments and clinical outcomes. Prolonged ED stays often reflect ED crowding or limited hospital capacity. We hypothesized that patients with non-ST-segment-elevation myocardial infarction who have ED stays of greater than 8 hours may have lower quality of care and worse outcomes.

METHODS

Using a secondary analysis of data from an observational registry (Can Rapid Risk Stratification of Unstable Angina Patients Suppress ADverse Outcomes with Early Implementation of the ACC/AHA Guidelines, CRUSADE), we compared rates of use of 5 individual acute (<24 hours) guideline-recommended therapies in patients with non-ST-segment-elevation myocardial infarction according to ED length of stay. Patients were grouped by length of stay (short [<4 hours], average [4 to 8 hours], or long [>8 hours]). Multivariable analyses were used to determine independent association of ED length of stay with acute medications and inhospital outcomes (death and myocardial infarction).

RESULTS

This analysis included 42,780 patients with non-ST-segment-elevation myocardial infarction. The median ED length of stay was 4.3 hours (25th to 75th percentile 2.9, 6.3); 15% of patients stayed longer than 8 hours. Patients who had long ED stays were more likely to be women and nonwhite and less likely to have health maintenance organization or private insurance. After adjustment, patients with long ED stays less often received guideline-recommended acute myocardial infarction therapies. Although risk-adjusted inhospital mortality rates were similar among groups, the rate of recurrent myocardial infarction increased among patients with long ED stays (odds ratio 1.23; 95% confidence interval 1.01 to 1.48) compared with those with average ED length of stay.

CONCLUSION

For patients with non-ST-segment-elevation myocardial infarction, long ED stays were associated with decreased use of guideline-recommended therapies and a higher risk of recurrent myocardial infarction. However, there was no observed difference in mortality. Factors associated with prolonged ED length of stay should be evaluated to optimize treatments and outcomes of patients with non-ST-segment-elevation myocardial infarction.

Enzymology of NAD+ homeostasis in man

This review describes the enzymes involved in human pyridine nucleotide metabolism starting with a detailed consideration of their major kinetic, molecular and structural properties. The presentation encompasses all the reactions starting from the de novo pyridine ring formation and leading to nicotinamide adenine dinucleotide (NAD(+)) synthesis and utilization. The regulation of NAD(+) homeostasis with respect to the physiological role played by the enzymes both utilizing NAD(+) through the nonredox NAD(+)-dependent reactions and catalyzing the recycling of the common product, nicotinamide, is discussed. The salient features of other enzymes such as NAD(+) pyrophosphatase, nicotinamide mononucleotide 5'-nucleotidase, nicotinamide riboside kinase and nicotinamide riboside phosphorylase, described under 'miscellaneous', are likewise presented.