Rural EMS STEMI Patients - Why the Delay to PCI?

BACKGROUND

The objective of this study is to identify patient and EMS agency factors associated with timely reperfusion of patients with ST-elevation myocardial infarction (STEMI).

METHODS

We conducted a cohort study of adult patients (≥18 years old) with STEMI activations from 2016 to 2020. Data was obtained from a regional STEMI registry, which included eight rural county EMS agencies and three North Carolina percutaneous coronary intervention (PCI) centers. On each patient, prehospital and in-hospital time intervals were abstracted. The primary outcome was the ability to achieve the 90-minute EMS FMC to PCI time goal (yes vs. no). We used generalized estimating equations accounting for within-agency clustering to evaluate the association between patient and agency factors and meeting first medical contact (FMC) to PCI time goal while accounting for clustering within the agency.

RESULTS

Among 365 rural STEMI patients 30.1% were female (110/365) with a mean age of 62.5 ± 12.7 years. PCI was performed within the time goal in 60.5% (221/365) of encounters. The FMC to PCI time goal was met in 45.5% (50/110) of women vs 69.8% (178/255) of men (p < 0.001). The median PCI center activation time was 12 min (IQR 7-19) in the group that received PCI within the time goal compared to 21 min (IQR 10-37) in the cohort that did not. After adjusting for loaded mileage and other clinical variables (e.g., pulse rate, hypertension etc.), the male sex was associated with an improved chance of meeting the goal of FMC to PCI (aOR: 2.94; 95% CI 2.11-4.10) compared to the female sex.

CONCLUSION

Nearly 40% of rural STEMI patients transported by EMS failed to receive FMC to PCI within 90 min. Women were less likely than men to receive reperfusion within the time goal, which represents an important health care disparity.

Delayed first medical contact to reperfusion time increases mortality in rural emergency medical services patients with ST-elevation myocardial infarction

BACKGROUND

ST-elevation myocardial infarction (STEMI) guidelines recommend an emergency medical services (EMS) first medical contact (FMC) to percutaneous coronary intervention (PCI) time of ≤90 min. The primary objective of this study was to evaluate the association between FMC to PCI time and mortality in rural STEMI patients.

METHODS

We conducted a cohort study of patients ≥18 years old with STEMI activations from January 2016 to March 2020. Data were obtained from a rural North Carolina Regional STEMI Data Registry, which included eight rural EMS agencies and three PCI centers, the National Cardiovascular Data Registry, and the EMS electronic health record. Prehospital and in-hospital time intervals were digitally abstracted. The outcome of index hospitalization mortality was compared between patients who did and did not meet FMC to PCI time goal using Fisher's exact tests. Negative predictive value (NPV) for index hospitalization death was calculated with 95% confidence intervals (CIs). A receiver operating characteristic curve was constructed and an optimal FMC to PCI time goal was identified by maximizing NPV to prevent index hospitalization death.

RESULTS

Among 365 rural EMS STEMI patients, 30.1% (110/365) were female with a mean ± SD age of 62.5 ± 12.7 years. PCI was performed within the 90-min time goal in 60.5% (221/365) of patients. Among these patients, 3% (11/365) died during initial STEMI hospitalization, with 1.4% (3/221) mortality in the group that met the 90-minute time goal compared to 5.6% (8/144) in patients exceeding the time goal (p = 0.03). Meeting the 90-min time goal yielded a 98.6% (95% CI 96.1%-99.7%) NPV for index death. A 78-min FMC to PCI time was the optimal cut point, yielding a NPV for index mortality of 99.3% (95% CI 96.1%-100%).

CONCLUSIONS

Death among rural patients with STEMI was four times more likely when they did not receive PCI within 90 min.

Cardiac Magnetic Resonance Imaging Versus Invasive-Based Strategies in Patients With Chest Pain and Detectable to Mildly Elevated Serum Troponin: A Randomized Clinical Trial

BACKGROUND

The optimal diagnostic strategy for patients with chest pain and detectable to mildly elevated serum troponin is not known. The objective was to compare clinical outcomes among an early decision for a noninvasive versus an invasive-based care pathway.

METHODS

The CMR-IMPACT trial (Cardiac Magnetic Resonance Imaging Strategy for the Management of Patients with Acute Chest Pain and Detectable to Elevated Troponin) was conducted at 4 United States tertiary care hospitals from September 2013 to July 2018. A convenience sample of 312 participants with acute chest pain symptoms and a contemporary troponin between detectable and 1.0 ng/mL were randomized early in their care to 1 of 2 care pathways: invasive-based (n=156) or cardiac magnetic resonance (CMR)-based (n=156) with modification allowed as the patient condition evolved. The primary outcome was a composite including death, myocardial infarction, and cardiac-related hospital readmission or emergency visits.

RESULTS

Participants (N=312, mean age, 60.6 years, SD 11.3; 125 women [59.9%]), were followed over a median of 2.6 years (95% CI, 2.4-2.9). Early assigned testing was initiated in 102 out of 156 (65.3%) CMR-based and 110 out of 156 (70.5%) invasive-based participants. The primary outcome (CMR-based versus invasive-based) occurred in 59% versus 52% (hazard ratio, 1.17 [95% CI, 0.86-1.57]), acute coronary syndrome after discharge 23% versus 22% (hazard ratio, 1.07 [95% CI, 0.67-1.71]), and invasive angiography at any time 52% versus 74% (hazard ratio, 0.66 [95% CI, 0.49-0.87]). Among patients completing CMR imaging, 55 out of 95 (58%) were safely identified for discharge based on a negative CMR and did not have angiography or revascularization within 90 days. Therapeutic yield of angiography was higher in the CMR-based arm (52 interventions in 81 angiographies [64.2%] versus 46 interventions in 115 angiographies [40.0%] in the invasive-based arm [P=0.001]).

CONCLUSIONS

Initial management with CMR or invasive-based care pathways resulted in no detectable difference in clinical and safety event rates. The CMR-based pathway facilitated safe discharge, enriched the therapeutic yield of angiography, and reduced invasive angiography utilization over long-term follow-up.

REGISTRATION

URL: https://www.

CLINICALTRIALS

gov; Unique identifier: NCT01931852.

Early Restrictive or Liberal Fluid Management for Sepsis-Induced Hypotension

BACKGROUND

Intravenous fluids and vasopressor agents are commonly used in early resuscitation of patients with sepsis, but comparative data for prioritizing their delivery are limited.

METHODS

In an unblinded superiority trial conducted at 60 U.S. centers, we randomly assigned patients to either a restrictive fluid strategy (prioritizing vasopressors and lower intravenous fluid volumes) or a liberal fluid strategy (prioritizing higher volumes of intravenous fluids before vasopressor use) for a 24-hour period. Randomization occurred within 4 hours after a patient met the criteria for sepsis-induced hypotension refractory to initial treatment with 1 to 3 liters of intravenous fluid. We hypothesized that all-cause mortality before discharge home by day 90 (primary outcome) would be lower with a restrictive fluid strategy than with a liberal fluid strategy. Safety was also assessed.

RESULTS

A total of 1563 patients were enrolled, with 782 assigned to the restrictive fluid group and 781 to the liberal fluid group. Resuscitation therapies that were administered during the 24-hour protocol period differed between the two groups; less intravenous fluid was administered in the restrictive fluid group than in the liberal fluid group (difference of medians, -2134 ml; 95% confidence interval [CI], -2318 to -1949), whereas the restrictive fluid group had earlier, more prevalent, and longer duration of vasopressor use. Death from any cause before discharge home by day 90 occurred in 109 patients (14.0%) in the restrictive fluid group and in 116 patients (14.9%) in the liberal fluid group (estimated difference, -0.9 percentage points; 95% CI, -4.4 to 2.6; P = 0.61); 5 patients in the restrictive fluid group and 4 patients in the liberal fluid group had their data censored (lost to follow-up). The number of reported serious adverse events was similar in the two groups.

CONCLUSIONS

Among patients with sepsis-induced hypotension, the restrictive fluid strategy that was used in this trial did not result in significantly lower (or higher) mortality before discharge home by day 90 than the liberal fluid strategy. (Funded by the National Heart, Lung, and Blood Institute; CLOVERS ClinicalTrials.gov number, NCT03434028.).

Monocyte chemoattractant protein-1 is not predictive of cardiac events in patients with non-low-risk chest pain

BACKGROUND

Prior studies suggest monocyte chemoattractant protein-1 (MCP-1) may be useful for risk stratifying ED patients with chest pain. We hypothesise that MCP-1 will be predictive of 90-day major adverse cardiovascular events (MACEs) in non-low-risk patients.

METHODS

A case-control study was nested within a prospective multicentre cohort (STOP-CP), which enrolled adult patients being evaluated for acute coronary syndrome at eight US EDs from 25 January 2017 to 06 September 2018. Patients with a History, ECG, Age, and Risk factor score (HEAR score) ≥4 or coronary artery disease (CAD), a non-ischaemic ECG, and non-elevated contemporary troponins at 0 and 3 hours were included. Cases were patients with 90-day MACE (all-cause death, myocardial infarction or revascularisation). Controls were patients without MACE selected with frequency matching using age, sex, race, and HEAR score or the presence of CAD. Serum MCP-1 was measured. Sensitivity and specificity were determined for cut-off points of 194 pg/mL, 200 pg/mL, 238 pg/mL and 281 pg/mL. Logistic regression adjusting for age, sex, race, and HEAR score/presence of CAD was used to determine the association between MCP-1 and 90-day MACE. A separate logistic model also included high-sensitivity troponin (hs-cTnT).

RESULTS

Among 40 cases and 179 controls, there was no difference in age (p=0.90), sex (p=1.00), race (p=0.85), or HEAR score/presence of CAD (p=0.89). MCP-1 was similar in cases (median 191.9 pg/mL, IQR: 161.8-260.1) and controls (median 196.6 pg/mL, IQR: 163.0-261.1) (p=0.48). At a cut-off point of 194 pg/mL, MCP-1 was 50.0% (95% CI 33.8% to 66.2%) sensitive and 46.9% (95% CI 39.4% to 54.5%) specific for 90-day MACE. After adjusting for covariates, MCP-1 was not associated with 90-day MACE at any cut-off point (at 194 pg/mL, OR 0.88 (95% CI 0.43 to 1.79)). When including hs-cTnT in the model, MCP-1 was not associated with 90-day MACE at any cut-off point (at 194 pg/mL, OR 0.85 (95% CI 0.42 to 1.73)).

CONCLUSION

MCP-1 is not predictive of 90-day MACE in patients with non-low-risk chest pain.

Prehospital Time Disparities for Rural Patients with Suspected STEMI

BACKGROUND

Rural patients with ST-elevation myocardial infarction (STEMI) may be less likely to receive prompt reperfusion therapy. This study's primary objective was to compare rural versus urban time intervals among a national cohort of prehospital patients with STEMI.

METHODS

The ESO Data Collaborative (Austin, TX), containing records from 1,366 emergency medical services agencies, was queried for adult 9-1-1 responses with suspected STEMI from 1/1/2018-12/31/2019. The scene address for each encounter was classified as either urban or rural using the 2010 US Census Urban Area Zip Code Tabulation Area relationship. The primary outcome was total EMS interval (9-1-1 call to hospital arrival); a key secondary outcome was the proportion of responses that had EMS intervals under 60 minutes. Generalized estimating equations were used to determine whether rural versus urban differences in interval outcomes occurred when adjusting for loaded mileage (distance from scene to hospital) and patient and clinical encounter characteristics.

RESULTS

Of 15,915,027 adult 9-1-1 transports, 23,655 records with suspected STEMI were included in the analysis. Most responses (91.6%, n = 21,661) occurred in urban settings. Median EMS interval was 37.6 minutes (IQR 30.0-48.0) in urban settings compared to 57.0 minutes (IQR 46.5-70.7) in rural settings (p < 0.01). Urban responses more frequently had EMS intervals <60 minutes (89.5%, n = 19,130), compared to rural responses (55.5%, n = 1,100, p < 0.01). After adjusting for loaded mileage, age, sex, race/ethnicity, abnormal vital signs, pain assessment, aspirin administration, and IV/IO attempt, rural location was associated with a 5.8 (95%CI 4.2-7.4) minute longer EMS interval than urban, and rural location was associated with a reduced chance of achieving EMS interval < 60 minutes (OR 0.40; 95%CI 0.33-0.49) as compared to urban location.

CONCLUSION

In this large national sample, rural location was associated with significantly longer EMS interval for patients with suspected STEMI, even after accounting for loaded mileage.

Prehospital Translation of Chest Pain Tools (RESCUE Study): Completion Rate and Inter-rater Reliability

INTRODUCTION

Chest pain is a common reason for ambulance transport. Acute coronary syndrome (ACS) and pulmonary embolism (PE) risk assessments, such as history, electrocardiogram, age, risk factors (HEAR); Emergency Department Assessment of Chest Pain Score (EDACS); Pulmonary Embolism Rule-out Criteria (PERC); and revised Geneva score, are well validated for emergency department (ED) use but have not been translated to the prehospital setting. The objectives of this study were to evaluate the 1) prehospital completion rate and 2) inter-rater reliability of chest pain risk assessments.

METHODS

We conducted a prospective observational cohort study in two emergency medical services (EMS) agencies (April 18, 2018 - January 2, 2019). Adults with acute, non-traumatic chest pain without ST-elevation myocardial infarction or unstable vital signs were accrued. Paramedics were trained to use the HEAR, EDACS, PERC, and revised Geneva score assessments. A subset of patients (a priori goal of N = 250) also had the four risk assessments completed by their treating clinicians in the ED, who were blinded to the EMS risk assessments. Outcomes were 1) risk assessments completion rate and 2) inter-rater reliability between EMS and ED assessments. An a priori goal for completion rate was set as >75%. We computed kappa with corresponding 95% confidence intervals (CI) for each risk assessment as a measure of inter-rater reliability. Acceptable agreement was defined a priori as kappa ≥ 0.60.

RESULTS

During the study period, 837 patients with acute chest pain were accrued. The median age was 54 years, interquartile range 43-66, with 53% female and 51% Black. Completion rates for each risk assessment were above goal: the HEAR score was completed on 95.1% (796/837), EDACS on 92.0% (770/837), PERC on 89.4% (748/837), and revised Geneva score on 90.7% (759/837) of patients. We assessed agreement in a subgroup of 260 patients. The HEAR score had a kappa of 0.51 (95% CI, 0.41-0.61); EDACS was 0.60 (95% CI, 0.49-0.72); PERC was 0.71 (95% CI, 0.61-0.81); and revised Geneva score was 0.51 (95% CI, 0.39-0.62).

CONCLUSION

The completion rate of risk assessments for ACS and PE was high for prehospital field personnel. The PERC and EDACS both demonstrated acceptable agreement between paramedics and clinicians in the ED, although assessments with better agreement are likely needed.

The Impact of Accelerated Diagnostic Protocol Implementation on Chest Pain Observation Unit Utilization

BACKGROUND

Data evaluating the impact of the history, ECG, age, risk factors, and troponin (HEART) Pathway on observation unit (OU) use is limited. The objective of this study is to determine how HEART Pathway implementation affects OU use.

METHODS

An analysis of OU registry data from October 2012 to October 2016, 2 years before and after HEART Pathway implementation at an academic medical center, was conducted. Adult patients placed in the OU for chest pain were included. The proportion of patients placed in the OU chest pain protocol per total OU volume and hospitalization and myocardial infarction (MI) rates were determined. Proportions before versus after implementation were compared using χ2 tests and age was compared using a Mann-Whitney U test.

RESULTS

During the study period, 1688 patients with chest pain before HEART Pathway implementation and 1692 after were included. The proportion of chest pain patients in the OU per total OU volume decreased following implementation from (57% [1688/2968] to 43.6% [1692/3882]; P < 0.001). Before HEART Pathway implementation, the hospitalization rate was 10.4% (175/1688) versus 12.4% (210/1692) after (P = 0.07). More patients were diagnosed with MI following implementation (0.8% [14/1665] vs. 2.0% [33/1686]; P = 0. 008). Median age was older postimplementation (52 years [IQR: 45-59 years] vs. 54 years [IQR: 48-64 years]; P < 0. 001).

CONCLUSIONS

HEART Pathway implementation resulted in management of higher risk patients in the OU. Following implementation, OU chest pain patients were older and were more likely to be hospitalized or diagnosed with MI.

Performance of Prehospital Use of Chest Pain Risk Stratification Tools: The RESCUE Study

BACKGROUND

Emergency medical services (EMS) assesses millions of patients with chest pain each year. However, tools validated to risk stratify patients for acute coronary syndrome (ACS) and pulmonary embolism (PE) have not been translated to the prehospital setting. The objective of this study is to assess the prehospital performance of risk stratification scores for 30-day major adverse cardiac events (MACE) and PE.

METHODS

A prospective observational cohort study of patients ≥21 years of age with acute chest pain who were transported by EMS in two North Carolina (NC) counties was conducted from 18 April 2018-2 January 2019. In this convenience sample, paramedics completed HEAR (history, electrocardiogram, age, risk factor), ED Assessment of Chest Pain Score (EDACS), Revised Geneva Score (RGS), and pulmonary embolism rule-out criteria (PERC) assessments on each patient. MACE (all-cause death, myocardial infarction, and revascularization) and PE at 30 days were determined by hospital records and NC Death Index. The positive (+LR) and negative likelihood ratios (-LR) of the risk scores for 30-day MACE and PE were calculated.

RESULTS

During the study period, 82.1% (687/837) patients had all four risk score assessments. The cohort was 51.1% (351/687) female, 49.5% (340/687) African American, and had a mean age of 55.0 years (SD 16.0). At 30 days, MACE occurred in 7.4% (51/687), PE occurred in 0.9% (6/687), and the combined outcome occurred in 8.2% (56/687). The HEAR score had a - LR of 0.46 (95% CI 0.27-0.78) and + LR of 1.48 (95% CI 1.26-1.74) for 30-day MACE. EDACS had a - LR of 0.61 (95% CI 0.46-0.81) and + LR of 2.53 (95% CI 1.86-3.46) for 30-day MACE. The PERC score had a - LR of 0 (95% CI 0.0-1.4) and a + LR of 1.38 (95% CI 1.32-1.45) for 30-day PE. The RGS score had a - LR of 0 (95% CI 0.0-0.65) and a + LR of 2.36 (95% CI 2.16-2.57) for 30-day PE. The combination of a low-risk HEAR score and negative PERC evaluation had a - LR of 0.25 (95% CI 0.08-0.76) and a + LR of 1.21 (95% CI 1.21-1.30) for 30-day MACE or PE.

CONCLUSION

The combination of a paramedic-obtained HEAR score and PERC evaluation performed best to exclude 30-day MACE and PE but was not sufficient for directing prehospital decision making.

Prehospital time for patients with acute cardiac complaints: A rural health disparity

OBJECTIVE

Delays in care for patients with acute cardiac complaints are associated with increased morbidity and mortality. The objective of this study was to quantify rural and urban differences in prehospital time intervals for patients with cardiac complaints.

METHODS

The ESO Data Collaborative dataset consisting of records from 1332 EMS agencies was queried for 9-1-1 encounters with acute cardiac problems among adults (age ≥ 18) from 1/1/2013-6/1/2018. Location was classified as rural or urban using the 2010 United States Census. The primary outcome was total prehospital time. Generalized estimating equations evaluated differences in the average times between rural and urban encounters while controlling for age, sex, race, transport mode, loaded mileage, and patient stability.

RESULTS

Among 428,054 encounters, the median age was 62 (IQR 50-75) years with 50.7% female, 75.3% white, and 10.3% rural. The median total prehospital, response, scene, and transport times were 37.0 (IQR 29.0-48.0), 6.0 (IQR 4.0-9.0), 16.0 (IQR 12.0-21.0), and 13.0 (IQR 8.0-21.0) minutes. Rural patients had an average total prehospital time that was 16.76 min (95%CI 15.15-18.38) longer than urban patients. After adjusting for covariates, average total time was 5.08 (95%CI 4.37-5.78) minutes longer for rural patients. Average response and transport time were 4.36 (95%CI 3.83-4.89) and 0.62 (95%CI 0.33-0.90) minutes longer for rural patients. Scene time was similar in rural and urban patients (0.09 min, 95%CI -0.15-0.33).

CONCLUSION

Rural patients with acute cardiac complaints experienced longer prehospital time than urban patients, even after accounting for other key variables, such as loaded mileage.

EMS blood collection from patients with acute chest pain reduces emergency department length of stay

BACKGROUND

Expediting the measurement of serum troponin by leveraging EMS blood collection could reduce the diagnostic time for patients with acute chest pain and help address Emergency Department (ED) overcrowding. However, this practice has not been examined among an ED chest pain patient population in the United States.

METHODS

A prospective observational cohort study of adults with non-traumatic chest pain without ST-segment elevation myocardial infarction was conducted in three EMS agencies between 12/2016-4/2018. During transport, paramedics obtained a patient blood sample that was sent directly to the hospital core lab for troponin measurement. On ED arrival HEART Pathway assessments were completed by ED providers as part of standard care. ED providers were blinded to troponin results from EMS blood samples. To evaluate the potential impact on length of stay (LOS), the time difference between EMS blood draw and first clinical ED draw was calculated. To determine the safety of using troponin measures from EMS blood samples, the diagnostic performance of the HEART Pathway for 30-day major adverse cardiac events (MACE: composite of cardiac death, myocardial infarction (MI), coronary revascularization) was determined using EMS troponin plus arrival ED troponin and EMS troponin plus a serial 3-h ED troponin.

RESULTS

The use of EMS blood samples for troponin measures among 401 patients presenting with acute chest pain resulted in a mean potential reduction in LOS of 72.5 ± SD 35.7 min. MACE at 30 days occurred in 21.0% (84/401), with 1 cardiac death, 78 MIs, and 5 revascularizations without MI. Use of the HEART Pathway with EMS and ED arrival troponin measures yielded a NPV of 98.0% (95% CI: 89.6-100). NPV improved to 100% (95% CI: 92.9-100) when using the EMS and 3-h ED troponin measures.

CONCLUSIONS

EMS blood collection used for core lab ED troponin measures could significantly reduce ED LOS and appears safe when integrated into the HEART Pathway.

Sex and race differences in safety and effectiveness of the HEART pathway accelerated diagnostic protocol for acute chest pain

BACKGROUND

The HEART Pathway is an accelerated diagnostic protocol for Emergency Department patients with possible acute coronary syndrome. The objective was to compare the safety and effectiveness of the HEART Pathway among women vs men and whites vs non-whites.

METHODS

A subgroup analysis of the HEART Pathway Implementation Study was conducted. Adults with chest pain were accrued from November 2013 to January 2016 from 3 Emergency Departments in North Carolina. The primary outcomes were death and myocardial infarction (MI) and hospitalization rates at 30 days. Logistic regression evaluated for interactions of accelerated diagnostic protocol implementation with sex or race and changes in outcomes within subgroups.

RESULTS

A total of 8,474 patients were accrued, of which 53.6% were female and 34.0% were non-white. The HEART Pathway identified 32.6% of females as low-risk vs 28.5% of males (P = 002) and 35.6% of non-whites as low-risk vs 28.0% of whites (P < .0001). Among low-risk patients, death or MI at 30 days occurred in 0.4% of females vs 0.5% of males (P = .70) and 0.5% of non-whites vs 0.3% of whites (P = .69). Hospitalization at 30 days was reduced by 6.6% in females (aOR: 0.74, 95% CI: 0.64-0.85), 5.1% in males (aOR: 0.87, 95% CI: 0.75-1.02), 8.6% in non-whites (aOR: 0.72, 95% CI: 0.60-0.86), and 4.5% in whites (aOR: 0.83, 95% CI: 0.73-0.94). Interactions were not significant.

CONCLUSION

Women and non-whites are more likely to be classified as low-risk by the HEART Pathway. HEART Pathway implementation is associated with decreased hospitalizations and a very low death and MI rate among low-risk patients regardless of sex or race.

Prehospital use of a modified HEART Pathway and point-of-care troponin to predict cardiovascular events

The HEART Pathway is a validated risk stratification protocol for Emergency Department patients with chest pain that has yet to be tested in the prehospital setting. This study seeks to test the performance of a prehospital modified HEART Pathway (PMHP). A prospective cohort study of adults with chest pain without ST-segment elevation myocardial infarction was conducted at three EMS agencies between 12/2016-1/2018. To complete a PMHP assessment, paramedics drew blood, measured point-of-care (POC) troponin (i-STAT; Abbott Point of Care) and calculated a HEAR score. Patients were stratified into three groups: high-risk based on an elevated troponin, low-risk based on a HEAR score <4 with a negative troponin, or moderate risk for a HEAR score ≥4 with a negative troponin. Sensitivity, specificity, negative and positive predictive values of the PMHP for detection of major adverse cardiac events (MACE: cardiac death, MI, or coronary revascularization) at 30-days were calculated. A total of 506 patients were accrued, with PMHP completed in 78.1% (395/506). MACE at 30-days occurred in 18.7% (74/395). Among these patients, 7.1% (28/395) were high risk yielding a specificity and PPV for 30-day MACE of 96.6% (95%CI: 94.0–98.3%) and 60.7% (95%CI: 40.6–78.6%) respectively. Low-risk assessments occurred in 31.4% (124/395), which were 90.5% (95%CI: 81.5–96.1%) sensitive for 30-day MACE with a NPV of 94.4% (95%CI: 88.7–97.7%). Moderate-risk assessments occurred in 61.5% (243/395), of which 20.6% had 30-day MACE. The PMHP is able to identify high-risk and low-risk groups with high specificity and negative predictive value for 30-day MACE.

Identification of very low-risk acute chest pain patients without troponin testing

BACKGROUND

The HEART Pathway combines a History ECG Age Risk factor (HEAR) score and serial troponins to risk stratify patients with acute chest pain. However, it is unclear whether patients with HEAR scores of <1 require troponin testing. The objective of this study is to measure the major adverse cardiac event (MACE) rate among patients with <1 HEAR scores and determine whether serial troponin testing is needed to achieve a miss rate <1%.

METHODS

A secondary analysis of the HEART Pathway Implementation Study was conducted. HEART Pathway risk assessments (HEAR scores and serial troponin testing at 0 and 3 hours) were completed by the providers on adult patients with chest pain from three US sites between November 2014 and January 2016. MACE (composite of death, myocardial infarction (MI) and coronary revascularisation) at 30 days was determined. The proportion of patients with HEAR scores of <1 diagnosed with MACE within 30 days was calculated. The impact of troponin testing on patients with HEAR scores of <1 was determined using Net Reclassification Improvement Index (NRI).

RESULTS

Providers completed HEAR assessments on 4979 patients and HEAR scores<1 occurred in 9.0% (447/4979) of patients. Among these patients, MACE at 30 days occurred in 0.9% (4/447; 95% CI 0.2% to 2.3%) with two deaths, two MIs and 0 revascularisations. The sensitivity and negative predictive value for MACE in the HEAR <1 was 97.8% (95%CI 94.5% to 99.4%) and 99.1% (95% CI 97.7% to 99.8%), respectively, and were not improved by troponin testing. Troponin testing in patients with HEAR <1 correctly reclassified two patients diagnosed with MACE, and was elevated among seven patients without MACE yielding an NRI of 0.9% (95%CI -0.7 to 2.4%).

CONCLUSION

These data suggest that patients with HEAR scores of 0 and 1 represent a very low-risk group that may not require troponin testing to achieve a missed MACE rate <1%. Trial registration number NCT02056964.

HEART Pathway Implementation Safely Reduces Hospitalizations at One Year in Patients With Acute Chest Pain

STUDY OBJECTIVE

We determine whether implementation of the HEART (History, ECG, Age, Risk Factors, Troponin) Pathway is safe and effective in emergency department (ED) patients with possible acute coronary syndrome through 1 year of follow-up.

METHODS

A preplanned analysis of 1-year follow-up data from a prospective pre-post study of 8,474 adult ED patients with possible acute coronary syndrome from 3 US sites was conducted. Patients included were aged 21 years or older, evaluated for possible acute coronary syndrome, and without ST-segment elevation myocardial infarction. Accrual occurred for 12 months before and after HEART Pathway implementation, from November 2013 to January 2016. The HEART Pathway was integrated into the electronic health record at each site as an interactive clinical decision support tool. After integration, ED providers prospectively used the HEART Pathway to identify patients with possible acute coronary syndrome as low risk (appropriate for early discharge without stress testing or angiography) or nonlow risk (appropriate for further inhospital evaluation). Safety (all-cause death and myocardial infarction) and effectiveness (hospitalization) at 1 year were determined from health records, insurance claims, and death index data.

RESULTS

Preimplementation and postimplementation cohorts included 3,713 and 4,761 patients, respectively. The HEART Pathway identified 30.7% of patients as low risk; 97.5% of them were free of death and myocardial infarction within 1 year. Hospitalization at 1 year was reduced by 7.0% in the postimplementation versus preimplementation cohort (62.1% versus 69.1%; adjusted odds ratio 0.70; 95% confidence interval 0.63 to 0.78). Rates of death or myocardial infarction at 1 year were similar (11.6% versus 12.4%; adjusted odds ratio 1.00; 95% confidence interval 0.87 to 1.16).

CONCLUSION

HEART Pathway implementation was associated with decreased hospitalizations and low adverse event rates among low-risk patients at 1-year follow-up.

Comparison of accelerated diagnostic pathways for acute chest pain risk stratification

BACKGROUND

The History Electrocardiogram Age Risk factor Troponin (HEART) Pathway and Emergency Department Assessment of Chest pain Score (EDACS) are validated accelerated diagnostic pathways designed to risk stratify patients presenting to the emergency department with chest pain. Data from large multisite prospective studies comparing these accelerated diagnostic pathways are limited.

METHODS

The HEART Pathway Implementation is a prospective three-site cohort study, which accrued adults with symptoms concerning for acute coronary syndrome. Physicians completed electronic health record HEART Pathway and EDACS risk assessments on participants. Major adverse cardiac events (death, myocardial infarction and coronary revascularisation) at 30 days were determined using electronic health record, insurance claims and death index data. Test characteristics for detection of major adverse cardiac events were calculated for both accelerated diagnostic pathways and McNemar's tests were used for comparisons.

RESULTS

5799 patients presenting to the emergency department were accrued, of which HEART Pathway and EDACS assessments were completed on 4399. Major adverse cardiac events at 30 days occurred in 449/4399 (10.2%). The HEART Pathway identified 38.4% (95% CI 37.0% to 39.9%) of patients as low-risk compared with 58.1% (95% CI 56.6% to 59.6%) identified as low-risk by EDACS (p<0.001). Major adverse cardiac events occurred in 0.4% (95% CI 0.2% to 0.9%) of patients classified as low-risk by the HEART Pathway compared with 1.0% (95% CI 0.7% to 1.5%) of patients identified as low-risk by EDACS (p<0.001). Thus, the HEART Pathway had a negative predictive value of 99.6% (95% CI 99.1% to 99.8%) for major adverse cardiac events compared with a negative predictive value of 99.0% (95% CI 98.5% to 99.3%) for EDACS.

CONCLUSIONS

EDACS identifies a larger proportion of patients as low-risk than the HEART Pathway, but has a higher missed major adverse cardiac events rate at 30 days. Physicians will need to consider their risk tolerance when deciding whether to adopt the HEART Pathway or EDACS accelerated diagnostic pathway.

TRIAL REGISTRATION NUMBER

NCT02056964.

Safely Identifying Emergency Department Patients With Acute Chest Pain for Early Discharge

BACKGROUND

The HEART Pathway (history, ECG, age, risk factors, and initial troponin) is an accelerated diagnostic protocol designed to identify low-risk emergency department patients with chest pain for early discharge without stress testing or angiography. The objective of this study was to determine whether implementation of the HEART Pathway is safe (30-day death and myocardial infarction rate <1% in low-risk patients) and effective (reduces 30-day hospitalizations) in emergency department patients with possible acute coronary syndrome.

METHODS

A prospective pre-post study was conducted at 3 US sites among 8474 adult emergency department patients with possible acute coronary syndrome. Patients included were ≥21 years old, investigated for possible acute coronary syndrome, and had no evidence of ST-segment-elevation myocardial infarction on ECG. Accrual occurred for 12 months before and after HEART Pathway implementation from November 2013 to January 2016. The HEART Pathway accelerated diagnostic protocol was integrated into the electronic health record at each site as an interactive clinical decision support tool. After accelerated diagnostic protocol integration, ED providers prospectively used the HEART Pathway to identify patients with possible acute coronary syndrome as low risk (appropriate for early discharge without stress testing or angiography) or non-low risk (appropriate for further in-hospital evaluation). The primary safety and effectiveness outcomes, death, and myocardial infarction (MI) and hospitalization rates at 30 days were determined from health records, insurance claims, and death index data.

RESULTS

Preimplementation and postimplementation cohorts included 3713 and 4761 patients, respectively. The HEART Pathway identified 30.7% as low risk; 0.4% of these patients experienced death or MI within 30 days. Hospitalization at 30 days was reduced by 6% in the postimplementation versus preimplementation cohort (55.6% versus 61.6%; adjusted odds ratio, 0.79; 95% CI, 0.71-0.87). During the index visit, more MIs were detected in the postimplementation cohort (6.6% versus 5.7%; adjusted odds ratio, 1.36; 95% CI, 1.12-1.65). Rates of death or MI during follow-up were similar (1.1% versus 1.3%; adjusted odds ratio, 0.88; 95% CI, 0.58-1.33).

CONCLUSIONS

HEART Pathway implementation was associated with decreased hospitalizations, increased identification of index visit MIs, and a very low death and MI rate among low-risk patients. These findings support use of the HEART Pathway to identify low-risk patients who can be safely discharged without stress testing or angiography.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov . Unique identifier: NCT02056964.

Prospective Assessment of the Feasibility of a Trial of Low-Tidal Volume Ventilation for Patients with Acute Respiratory Failure

RATIONALE

Low-tidal volume ventilation (LTVV; 6 ml/kg) benefits patients with acute respiratory distress syndrome and may aid those with other causes of respiratory failure. Current early ventilation practices are poorly defined.

OBJECTIVES

We observed patients with acute respiratory failure to assess the feasibility of a pragmatic trial of LTVV and to guide experimental design.

METHODS

We prospectively enrolled consecutive patients with acute respiratory failure admitted to intensive care units expected to participate in the proposed trial. We collected clinical data as well as information on initial and daily ventilator settings and inpatient mortality. We estimated the benefit of LTVV using predictive linear and nonlinear models. We simulated models to estimate power and feasibility of a cluster-randomized trial of LTVV versus usual care in acute respiratory failure.

RESULTS

We included 2,484 newly mechanically ventilated patients (31% with acute respiratory distress syndrome) from 49 hospitals. Hospital mortality was 28%. Mean initial tidal volume was 7.1 ml/kg predicted body weight (95% confidence interval, 7.1-7.2), with 78% of patients receiving tidal volumes less than or equal to 8 ml/kg. Our models estimated a mortality benefit of 0-2% from LTVV compared with usual care. Simulation of a stepped-wedged cluster-randomized trial suggested that enrollment of 106,361 patients would be necessary to achieve greater than 90% power.

CONCLUSIONS

Use of initial tidal volumes less than 8 ml/kg predicted body weight was common at hospitals participating in the National Heart, Lung, and Blood Institute Prevention and Early Treatment of Acute Lung Injury (PETAL) Network. After considering the size and budgetary requirement for a cluster-randomized trial of LTVV versus usual care in acute respiratory failure, the PETAL Network deemed the proposed trial infeasible. A rapid observational study and simulations to model anticipated power may help better design trials.

ACES (Accelerated Chest Pain Evaluation With Stress Imaging) Protocols Eliminate Testing Disparities in Patients With Chest Pain

BACKGROUND

Patients from racial and ethnic minority groups presenting to the Emergency Department (ED) with chest pain experience lower odds of receiving stress testing compared with nonminorities. Studies have demonstrated that care pathways administered within the ED can reduce health disparities, but this has yet to be studied as a strategy to increase stress testing equity.

METHODS

A secondary analysis from 3 randomized clinical trials involving ED patients with acute chest pain was performed to determine whether a care pathway, ACES (Accelerated Chest pain Evaluation with Stress imaging), reduces the racial disparity in index visit cardiac testing between African American (AA) and White patients. Three hundred thirty-four participants with symptoms and findings indicating intermediate to high risk for acute coronary syndrome were enrolled in 3 clinical trials. Major exclusions were ST-segment elevation, initial troponin elevation, and hemodynamic instability. Participants were randomly assigned to receive usual inpatient care, or ACES. The ACES care pathway includes placement in observation for serial cardiac markers, with an expectation for stress imaging. The primary outcome was index visit objective cardiac testing, compared among AA and White participants.

RESULTS

AA participants represented 111/329 (34%) of the study population, 80/220 (36%) of the ACES group and 31/109 (28%) of the usual care group. In usual care, objective testing occurred less frequently among AA (22/31, 71%) than among White (69/78, 88%, P = 0.027) participants, primarily driven by cardiac catheterization (3% vs. 24%; P = 0.012). In ACES, testing rates did not differ by race [AA 78/80 (98%) vs. White 138/140 (99%); P = 0.623]. At 90 days, death, MI, and revascularization did not differ in either group between AA and White participants.

CONCLUSIONS

A care pathway with the expectation for stress imaging eliminates the racial disparity among AA and White participants with chest pain in the acquisition of index-visit cardiovascular testing.

The HEART Pathway Randomized Controlled Trial One-year Outcomes

OBJECTIVE

The objective was to determine the impact of the HEART Pathway on health care utilization and safety outcomes at 1 year in patients with acute chest pain.

METHODS

Adult emergency department (ED) patients with chest pain (N = 282) were randomized to the HEART Pathway or usual care. In the HEART Pathway arm, ED providers used the HEART score and troponin measures (0 and 3 hours) to risk stratify patients. Usual care was based on American College of Cardiology/American Heart Association guidelines. Major adverse cardiac events (MACE-cardiac death, myocardial infarction [MI], or coronary revascularization), objective testing (stress testing or coronary angiography), and cardiac hospitalizations and ED visits were assessed at 1 year. Randomization arm outcomes were compared using Fisher's exact tests.

RESULTS

A total of 282 patients were enrolled, with 141 randomized to each arm. MACE at 1 year occurred in 10.6% (30/282): 9.9% in the HEART Pathway arm (14/141; 10 MIs, four revascularizations without MI) versus 11.3% in usual care (16/141; one cardiac death, 13 MIs, two revascularizations without MI; p = 0.85). Among low-risk HEART Pathway patients, 0% (0/66) had MACE, with a negative predictive value (NPV) of 100% (95% confidence interval = 93%-100%). Objective testing through 1 year occurred in 63.1% (89/141) of HEART Pathway patients compared to 71.6% (101/141) in usual care (p = 0.16). Nonindex cardiac-related hospitalizations and ED visits occurred in 14.9% (21/141) and 21.3% (30/141) of patients in the HEART Pathway versus 10.6% (15/141) and 16.3% (23/141) in usual care (p = 0.37, p = 0.36).

CONCLUSIONS

The HEART Pathway had a 100% NPV for 1-year safety outcomes (MACE) without increasing downstream hospitalizations or ED visits. Reduction in 1-year objective testing was not significant.

Usefulness of Serial 12-Lead Electrocardiograms in Predicting 30-Day Outcomes in Patients With Undifferentiated Chest Pain (the ASAP CATH Study)

An initial electrocardiogram (ECG) and serial troponin measurements are both independently and incrementally predictive of acute coronary syndrome in patients presenting with undifferentiated chest pain in the Emergency Department (ED). However, it is unclear if serial (ECGs) add significant to the contemporary diagnostic evaluation of this patient group. The ASAP CATH study was a single center, prospective study that enrolled patients presenting to an ED with undifferentiated chest pain. In addition to standard clinical evaluation, serial ECGs were performed at 90-minute intervals to evaluate whether serial changes suggestive of ischemia developed (Q waves, ST elevation or depression, or T-wave inversion). Total 365 subjects were enrolled from March 2014 to May 2015. Serial ECG changes developed in 6.6% (n = 24 of 365), the most common being the development of T-wave inversion (66.7%, n = 16 of 24). The sensitivity and positive predictive value of serial ECG changes were poor (<30%), with a less areas under the curve (0.55) compared with serial troponins alone (0.83). The addition of serial ECG changes to Thrombolysis In Myocardial Infarction risk scoring showed a decrease in the net reclassification index for major adverse cardiovascular events (-0.04, p <0.1) and was not significant for the prediction of major adverse cardiovascular events and/or acute coronary syndrome in 30 days (-0.003, p = 0.94). In conclusion, routine serial ECG evaluation for patients presenting with undifferentiated chest pain in the ED may not significantly improved diagnostic prognosis beyond current standard evaluation modalities.

Monocyte Chemoattractant Protein-1 as a Predictor of Coronary Atherosclerosis in Patients Receiving Coronary Angiography

BACKGROUND

Animal studies suggest that monocyte chemoattractant protein-1 (MCP-1) is a promising biomarker for coronary artery atherosclerosis (CAA), but human studies have been inconclusive.

OBJECTIVE

To determine potential relationships between plasma MCP-1 and CAA in patients with acute chest pain.

METHODS

A secondary analysis of 150 patients enrolled in emergency department chest pain risk stratification clinical investigations was conducted. Participants with stored blood and known coronary phenotypes (determined by coronary angiography) were selected using stratified randomization such that 50 patients were included into 3 groups: (1) no angiographic evidence of CAA, (2) nonobstructive CAA, and (3) obstructive CAA (stenosis ≥ 70%). Plasma MCP-1 levels were determined by enzyme-linked immunosorbent assay. The association between MCP-1 and obstructive CAA or any CAA was modeled using logistic regression. Variables in the unreduced model included age, sex, race, prior diagnosis of CAA or acute coronary syndrome, hyperlipidemia, hypertension, diabetes, smoking, and cardiac troponin I measurement.

RESULTS

Among the 150 participants, 65.3% (98/150) had invasive coronary angiography and 34.7% (52/150) had coronary computed tomographic angiography. Myocardial infarction occurred in 27.3% (41/150) and coronary revascularization occurred in 26% (39/150) of the participants. Each 10 pg/mL increase in MCP-1 measurement was associated with an odds ratio of 1.12 (95% confidence interval, 1.06-1.19) for obstructive CAA. MCP-1 remained a significant predictor of obstructive CAA and any CAA after adjustment for age, sex, race, traditional cardiac risk factors, and cardiac troponin I.

CONCLUSIONS

MCP-1 is independently associated with CAA among emergency department patients with chest pain.

Liberal Versus Restrictive Intravenous Fluid Therapy for Early Septic Shock: Rationale for a Randomized Trial

Prompt intravenous fluid therapy is a fundamental treatment for patients with septic shock. However, the optimal approach for administering intravenous fluid in septic shock resuscitation is unknown. Two competing strategies are emerging: a liberal fluids approach, consisting of a larger volume of initial fluid (50 to 75 mL/kg [4 to 6 L in an 80-kg adult] during the first 6 hours) and later use of vasopressors, versus a restrictive fluids approach, consisting of a smaller volume of initial fluid (≤30 mL/kg [≤2 to 3 L]), with earlier reliance on vasopressor infusions to maintain blood pressure and perfusion. Early fluid therapy may enhance or maintain tissue perfusion by increasing venous return and cardiac output. However, fluid administration may also have deleterious effects by causing edema within vital organs, leading to organ dysfunction and impairment of oxygen delivery. Conversely, a restrictive fluids approach primarily relies on vasopressors to reverse hypotension and maintain perfusion while limiting the administration of fluid. Both strategies have some evidence to support their use but lack robust data to confirm the benefit of one strategy over the other, creating clinical and scientific equipoise. As part of the National Heart, Lung, and Blood Institute Prevention and Early Treatment of Acute Lung Injury Network, we designed a randomized clinical trial to compare the liberal and restrictive fluids strategies, the Crystalloid Liberal or Vasopressor Early Resuscitation in Sepsis trial. The purpose of this article is to review the current literature on approaches to early fluid resuscitation in adults with septic shock and outline the rationale for the upcoming trial.

Validation of the No Objective Testing Rule and Comparison to the HEART Pathway

BACKGROUND

The no objective testing rule (NOTR) is a decision aid designed to safely identify emergency department (ED) patients with chest pain who do not require objective testing for coronary artery disease.

OBJECTIVES

The objective was to validate the NOTR in a cohort of U.S. ED patients with acute chest pain and compare its performance to the HEART Pathway.

METHODS

A secondary analysis of 282 participants enrolled in the HEART Pathway randomized controlled trial was conducted. Each patient was classified as low risk or at risk by the NOTR. Sensitivity for major adverse cardiac events (MACE) at 30 days was calculated in the entire study population. NOTR and HEART Pathways were compared among patients randomized to the HEART Pathway in the parent trial using McNemar's test and the net reclassification improvement (NRI).

RESULTS

Major adverse cardiac events occurred in 22/282 (7.8%) participants, including no deaths, 16/282 (5.6%) with myocardial infarction (MI), and 6/282 (2.1%) with coronary revascularization without MI. NOTR was 100% (95% confidence interval [CI] = 84.6%-100%) sensitive for MACE and identified 78/282 patients (27.7%, 95% = CI 22.5-33.3%) as low risk. In the HEART Pathway arm (n = 141), both NOTR and HEART Pathway identified all patients with MACE as at risk. Compared to NOTR, the HEART Pathway was able to correctly reclassify 27 patients without MACE as low risk, yielding a NRI of 20.8% (95% CI = 11.3%-30.2%).

CONCLUSIONS

Within a U.S. cohort of ED patients with chest pain, the NOTR and HEART Pathway were 100% sensitive for MACE at 30 days. However, the HEART Pathway identified more patients suitable for early discharge than the NOTR.

Can a Point-of-Care Troponin I Assay be as Good as a Central Laboratory Assay? A MIDAS Investigation

BACKGROUND

We aimed to compare the diagnostic accuracy of the Alere Triage Cardio3 Tropinin I (TnI) assay (Alere, Inc., USA) and the PathFast cTnI-II (Mitsubishi Chemical Medience Corporation, Japan) against the central laboratory assay Singulex Erenna TnI assay (Singulex, USA).

METHODS

Using the Markers in the Diagnosis of Acute Coronary Syndromes (MIDAS) study population, we evaluated the ability of three different assays to identify patients with acute myocardial infarction (AMI). The MIDAS dataset, described elsewhere, is a prospective multicenter dataset of emergency department (ED) patients with suspected acute coronary syndrome (ACS) and a planned objective myocardial perfusion evaluation. Myocardial infarction (MI) was diagnosed by central adjudication.

RESULTS

The C-statistic with 95% confidence intervals (CI) for diagnosing MI by using a common population (n=241) was 0.95 (0.91-0.99), 0.95 (0.91-0.99), and 0.93 (0.89-0.97) for the Triage, Singulex, and PathFast assays, respectively. Of samples with detectable troponin, the absolute values had high Pearson (R(P)) and Spearman (R(S)) correlations and were R(P)=0.94 and R(S)=0.94 for Triage vs Singulex, R(P)=0.93 and R(S)=0.85 for Triage vs PathFast, and R(P)=0.89 and R(S)=0.73 for PathFast vs Singulex.

CONCLUSIONS

In a single comparative population of ED patients with suspected ACS, the Triage Cardio3 TnI, PathFast, and Singulex TnI assays provided similar diagnostic performance for MI.

Use of the HEART Pathway with high sensitivity cardiac troponins: A secondary analysis

OBJECTIVES

The HEART Pathway combines a decision aid and serial contemporary cardiac troponin I (cTnI) measures to achieve >99% sensitivity for major adverse cardiac events (MACE) at 30days and early discharge rates >20%. However, the impact of integrating high-sensitivity troponin (hs-cTn) measures into the HEART Pathway has yet to be determined. In this analysis we compare test characteristics of the HEART Pathway using hs-cTnI, hs-cTnT, or cTnI.

DESIGN & METHODS

A secondary analysis of participants enrolled in the HEART Pathway RCT was conducted. Each patient was risk stratified by the cTn-HEART Pathway (Siemens TnI-Ultra at 0- and 3-h) and a hs-cTn-HEART Pathway using hs-cTnI (Abbott) or hs-cTnT (Roche) at 3-h. The early discharge rate, sensitivity, specificity, and negative predictive value (NPV) for MACE (death, myocardial infarction, or coronary revascularization) at 30days were calculated.

RESULTS

hs-cTnI measures were available on 133 patients. MACE occurred in 11/133 (8%) of these patients. Test characteristics for the HEART Pathway using serial cTnI vs 3hour hs-cTnI were the same: sensitivity (100%, 95%CI: 72-100%), specificity (49%, 95%CI: 40-58%), NPV (100%, 95%CI: 94-100%), and early discharge rate (45%, 95%CI: 37-54%). The HEART Pathway using hs-cTnT missed one MACE event (myocardial infarction): sensitivity (91%, 95%CI: 59-100%), specificity (48%, 95%CI: 39-57%), NPV (98%, 95%CI: 91-100%), and early discharge rate (45%, 95%CI: 37-54%).

CONCLUSIONS

There was no difference in the test characteristics of the HEART Pathway whether using cTnI or hs-cTnI, with both achieving 100% sensitivity and NPV. Use of hs-cTnT with the HEART Pathway was associated with one missed MACE.

Cost analysis of the History, ECG, Age, Risk factors, and initial Troponin (HEART) Pathway randomized control trial

INTRODUCTION

The HEART Pathway is a diagnostic protocol designed to identify low-risk patients presenting to the emergency department with chest pain that are safe for early discharge. This protocol has been shown to significantly decrease health care resource utilization compared with usual care. However, the impact of the HEART Pathway on the cost of care has yet to be reported.

METHODS AND RESULTS

We performed a cost analysis of patients enrolled in the HEART Pathway trial, which randomized participants to either usual care or the HEART Pathway protocol. For low-risk patients, the HEART Pathway recommended early discharge from the emergency department without further testing. We compared index visit cost, cost at 30 days, and cardiac-related health care cost at 30 days between the 2 treatment arms. Costs for each patient included facility and professional costs. Cost at 30 days included total inpatient and outpatient costs, including the index encounter, regardless of etiology. Cardiac-related health care cost at 30 days included the index encounter and costs adjudicated to be cardiac-related within that period. Two hundred seventy of the 282 patients enrolled in the trial had cost data available for analysis. There was a significant reduction in cost for the HEART Pathway group at 30 days (median cost savings of $216 per individual), which was most evident in low-risk (Thrombolysis In Myocardial Infarction score of 0-1) patients (median savings of $253 per patient) and driven primarily by lower cardiac diagnostic costs in the HEART Pathway group.

CONCLUSIONS

Using the HEART Pathway as a decision aid for patients with undifferentiated chest pain resulted in significant cost savings.

Clinical Assessment of a Point-of-Care Serum Amyloid A Assay in Foals with Bronchopneumonia

Background

Despite the paucity of data available, stall‐side serum amyloid (SAA) assays are commonly used to make diagnostic and treatment decisions in foals with bronchopneumonia.

Hypothesis

Measurement of SAA concentrations can accurately differentiate pneumonic from healthy foals.

Animals

Fifty‐four pneumonic foals between 3 weeks and 5 months of age were compared to 44 healthy controls. In addition, 47 foals on a farm endemic for R. equi infections were studied.

Methods

Serum samples were collected from pneumonic foals at hospital admission. Foals were categorized as having pneumonia caused by R. equi or by other microorganisms based on culture of a tracheobronchial aspirate. In addition, serum samples were obtained at 2‐week intervals from foals born at a farm endemic for R. equi. SAA concentrations were measured by a point‐of‐care assay. Diagnostic performance of SAA was assessed by use of receiver operating characteristic curves.

Results

Concentrations of SAA in foals with bronchopneumonia were significantly (P < 0.001) higher than those of healthy foals, but 15 of 54 pneumonic foals (28%) had SAA concentrations <5 μg/mL. There was no correlation between SAA concentrations and radiographic score in foals with R. equi pneumonia. The ability of SAA to predict development of R. equi pneumonia at the endemic farm was limited with a sensitivity of 64% and a specificity of 77%.

Conclusion and clinical importance

Overall, SAA concentrations are significantly higher in pneumonic than in healthy foals. However, performance of SAA in detecting pneumonic foals is limited by the high proportion of false‐positive and false‐negative results.

HEART Pathway Accelerated Diagnostic Protocol Implementation: Prospective Pre-Post Interrupted Time Series Design and Methods

Background

Most patients presenting to US Emergency Departments (ED) with chest pain are hospitalized for comprehensive testing. These evaluations cost the US health system >$10 billion annually, but have a diagnostic yield for acute coronary syndrome (ACS) of <10%. The history/ECG/age/risk factors/troponin (HEART) Pathway is an accelerated diagnostic protocol (ADP), designed to improve care for patients with acute chest pain by identifying patients for early ED discharge. Prior efficacy studies demonstrate that the HEART Pathway safely reduces cardiac testing, while maintaining an acceptably low adverse event rate.

Objective

The purpose of this study is to determine the effectiveness of HEART Pathway ADP implementation within a health system.

Methods

This controlled before-after study will accrue adult patients with acute chest pain, but without ST-segment elevation myocardial infarction on electrocardiogram for two years and is expected to include approximately 10,000 patients. Outcomes measures include hospitalization rate, objective cardiac testing rates (stress testing and angiography), length of stay, and rates of recurrent cardiac care for participants.

Results

In pilot data, the HEART Pathway decreased hospitalizations by 21%, decreased hospital length (median of 12 hour reduction), without increasing adverse events or recurrent care. At the writing of this paper, data has been collected on >5000 patient encounters. The HEART Pathway has been fully integrated into health system electronic medical records, providing real-time decision support to our providers.

Conclusions

We hypothesize that the HEART Pathway will safely reduce healthcare utilization. This study could provide a model for delivering high-value care to the 8-10 million US ED patients with acute chest pain each year.

ClinicalTrial

Clinicaltrials.gov NCT02056964; https://clinicaltrials.gov/ct2/show/NCT02056964 (Archived by WebCite at http://www.webcitation.org/6ccajsgyu)

Adherence to an Accelerated Diagnostic Protocol for Chest Pain: Secondary Analysis of the HEART Pathway Randomized Trial

OBJECTIVES

Accelerated diagnostic protocols (ADPs), such as the HEART Pathway, are gaining popularity in emergency departments (EDs) as tools used to risk stratify patients with acute chest pain. However, provider nonadherence may threaten the safety and effectiveness of ADPs. The objective of this study was to determine the frequency and impact of ADP nonadherence.

METHODS

A secondary analysis of participants enrolled in the HEART Pathway RCT was conducted. This trial enrolled 282 adult ED patients with symptoms concerning for acute coronary syndrome without ST-elevation on electrocardiogram. Patients randomized to the HEART Pathway (N = 141) were included in this analysis. Outcomes included index visit disposition, nonadherence, and major adverse cardiac events (MACEs) at 30 days. MACE was defined as death, myocardial infarction, or revascularization. Nonadherence was defined as: 1) undertesting-discharging a high-risk patient from the ED without objective testing (stress testing or coronary angiography) or 2) overtesting-admitting or obtaining objective testing on a low-risk patient.

RESULTS

Nonadherence to the HEART Pathway occurred in 28 of 141 patients (20%, 95% confidence interval [CI] = 14% to 27%). Overtesting occurred in 19 of 141 patients (13.5%, 95% CI = 8% to 19%) and undertesting in nine of 141 patients (6%, 95% CI = 3% to 12%). None of these 28 patients suffered MACE. The net effect of nonadherence was 10 additional admissions among patients identified as low-risk and appropriate for early discharge (absolute decrease in discharge rate of 7%, 95% CI = 3% to 13%).

CONCLUSIONS

Real-time use of the HEART Pathway resulted in a nonadherence rate of 20%, mostly due to overtesting. None of these patients had MACE within 30 days. Nonadherence decreased the discharge rate, attenuating the HEART Pathway's impact on health care use.

Performance of the 2-hour accelerated diagnostic protocol within the American College of Radiology Imaging Network PA 4005 cohort

OBJECTIVES

The 2-hour accelerated diagnostic protocol (ADAPT) is a decision rule designed to identify emergency department (ED) patients with chest pain for early discharge. Previous studies in the Asia-Pacific region demonstrated high sensitivity (97.9% to 99.7%) for major adverse cardiac events (MACE) at 30 days. The objective of this study was to determine the validity of ADAPT for risk stratification in a cohort of U.S. ED patients with suspected acute coronary syndrome (ACS).

METHODS

A secondary analysis of participants enrolled in the American College of Radiology Imaging Network (ACRIN) PA 4005 trial was conducted. This trial enrolled 1,369 patients at least 30 years old with symptoms suggestive of ACS. All data elements were collected prospectively at the time of enrollment. Each patient was classified as low risk or at risk by ADAPT. Early discharge rate and sensitivity for MACE, defined as cardiac death, myocardial infarction (MI), or coronary revascularization at 30 days, were calculated.

RESULTS

Of 1,140 patients with complete biomarker data, MACE occurred in 31 patients (2.7%). Among 551 of the 1,140 (48.3%, 95% confidence interval [CI] = 45.4% to 51.3%), ADAPT identified for early discharge; five of the 551 (0.9%, 95% CI = 0.3% to 2.1%) had MACE at 30 days. ADAPT was 83.9% (95% CI = 66.3% to 94.5%) sensitive, identifying 26 of 31 patients with MACE. Of the five patients identified for early discharge by ADAPT with MACE, there were no deaths, one patient with MI, and five with revascularizations.

CONCLUSIONS

In this first North American application of the ADAPT strategy, sensitivity for MACE within 30 days was 83.9%. One missed adverse event was a MI, with the remainder representing coronary revascularizations. The effect of missing revascularization events needs further investigation.

The HEART Pathway randomized trial: identifying emergency department patients with acute chest pain for early discharge

BACKGROUND

The HEART Pathway is a decision aid designed to identify emergency department patients with acute chest pain for early discharge. No randomized trials have compared the HEART Pathway with usual care.

METHODS AND RESULTS

Adult emergency department patients with symptoms related to acute coronary syndrome without ST-elevation on ECG (n=282) were randomized to the HEART Pathway or usual care. In the HEART Pathway arm, emergency department providers used the HEART score, a validated decision aid, and troponin measures at 0 and 3 hours to identify patients for early discharge. Usual care was based on American College of Cardiology/American Heart Association guidelines. The primary outcome, objective cardiac testing (stress testing or angiography), and secondary outcomes, index length of stay, early discharge, and major adverse cardiac events (death, myocardial infarction, or coronary revascularization), were assessed at 30 days by phone interview and record review. Participants had a mean age of 53 years, 16% had previous myocardial infarction, and 6% (95% confidence interval, 3.6%-9.5%) had major adverse cardiac events within 30 days of randomization. Compared with usual care, use of the HEART Pathway decreased objective cardiac testing at 30 days by 12.1% (68.8% versus 56.7%; P=0.048) and length of stay by 12 hours (9.9 versus 21.9 hours; P=0.013) and increased early discharges by 21.3% (39.7% versus 18.4%; P<0.001). No patients identified for early discharge had major adverse cardiac events within 30 days.

CONCLUSIONS

The HEART Pathway reduces objective cardiac testing during 30 days, shortens length of stay, and increases early discharges. These important efficiency gains occurred without any patients identified for early discharge suffering MACE at 30 days.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique Identifier: NCT01665521.

Frequency of electrocardiogram testing among HIV-infected patients at risk for medication-induced QTc prolongation

OBJECTIVES

HIV-infected patients are commonly prescribed several medications and are thus at risk for drug interactions that may result in QTc prolongation. We sought (1) to identify the frequency of electrocardiogram (ECG) monitoring (2), to determine the prevalence of drug interactions involving QTc-prolonging medications, and (3) to quantify the prevalence of QTc prolongation.

METHODS

A cross-sectional study was conducted among HIV-infected adults. Demographics, medications, drug interactions and comorbidities were abstracted from patients' medical records. Abnormal QTc interval was defined per the UK Committee for Proprietary Medicinal Products. Clinical characteristics were compared among ECG recipients and nonrecipients. Among ECG recipients, the prevalence and predictors of QTc prolongation were assessed.

RESULTS

Among the 454 patients included in the study, 80.8% were prescribed a medication associated with QTc prolongation and 39% had drug interactions expected to increase QTc prolongation risk. There were 138 patients (30.3%) who received ECG testing. Receipt of ECG monitoring was associated with increasing age, diabetes, increasing total number of medications and gastroesophageal reflux disease. Among ECG recipients, the prevalence of abnormal QTc interval was 27.5%. Chronic kidney disease [prevalence ratio (PR) 3.47; 95% confidence interval (CI) 1.37-8.83; P = 0.009], hepatitis C virus coinfection (PR 2.26; 95% CI 0.97-5.27; P = 0.06) and hypertension (PR 2.11; 95% CI 0.93-4.81; P = 0.07) were independently associated with an abnormal QTc interval.

CONCLUSIONS

A low frequency of ECG testing was observed, despite a high use of medications associated with QTc prolongation. The risk of abnormal QTc interval was highest among patients with chronic kidney disease, hypertension and hepatitis C virus coinfection.

Central versus local adjudication of myocardial infarction in a cardiac biomarker trial

OBJECTIVES

The impact of regulatory requirements, which require central adjudication for the diagnosis of acute myocardial infarction (AMI) in cardiac biomarker studies, is unclear. We determined the impact of local (at the site of subject enrollment) versus central adjudication of AMI on final diagnosis.

METHODS

This is a retrospective analysis of data from the Myeloperoxidase in the Diagnosis of Acute Coronary Syndromes Study, an 18-center prospective study of patients with suspected acute coronary syndromes, with enrollment from December 19, 2006, to September 20, 2007. Local adjudication of AMI was performed by a single site investigator at each center following the protocol-specified definition and according to the year 2000 definition of AMI, which based cardiac troponin (cTn) elevation on local cut points for each of the 13 different assays. After completion of the Myeloperoxidase in the Diagnosis of Acute Coronary Syndromes Study primary analysis and to evaluate a new troponin assay, a Food and Drug Administration-mandated central adjudication was performed by 3 investigators at different institutions. This adjudication used the 2007 Universal Definition of AMI, which differs by use of the manufacturer's 99th percentile cTn cut point. We describe the outcome of this process and compare it with the local adjudication. Central adjudicators were not blinded to local adjudications. For central adjudication, discrepant diagnoses were resolved by consensus. Local versus central cTn cut points differed for 6 assays. Both definitions required a rise and/or fall of cTn. Discrepant cases were reviewed by the lead author. Difficult cases were defined as having a difference between local and central adjudication, an elevated cTn with a temporal rise and fall, and a negative or absent risk stratification test. Statistics were by χ(2), κ, and logistic regression.

RESULTS

Of 1,107 patients enrolled, 11 had indeterminate central adjudication, leaving 1,096 for analysis. In spite of high agreement across central versus local adjudicators, κ = 0.79 (95% CI [0.73, 0.85]), AMI was diagnosed more often by central adjudication, 134 (12.2%) versus 104 (9.5%), with 44 local diagnoses (4%) changed from non-AMI to AMI (n = 37) or AMI to non-AMI (n = 7) (P < .001). These 44 represented 34% (95% CI 26%-42%) of 141 cases in which either central or local adjudication was AMI. Of diagnoses changed to AMI, 3 reasons contributed approximately one-third each: the local use of a non-99th percentile cTn cutoff (32%), the possibility of human error (34%), and difficult cases (34%).

CONCLUSION

Despite an acceptable κ, over a third of patients with a diagnosis of AMI were not assigned that diagnosis by both sets of adjudicators. This supports the importance of 1 standard method for diagnosis of AMI.

Incremental value of objective cardiac testing in addition to physician impression and serial contemporary troponin measurements in women

OBJECTIVES

Guidelines recommend that patients presenting to the emergency department (ED) with chest pain who are at low risk for acute coronary syndrome (ACS) receive an objective cardiac evaluation with a stress test or coronary imaging. It is uncertain whether all women derive benefit from this process. The study aim was to determine the incremental value of objective cardiac testing after serial cardiac markers and physician risk assessment.

METHODS

Women enrolled in the 18-site Myeloperoxidase in the Diagnosis of Acute Coronary Syndrome (MIDAS) study had serial troponin I measured at time 0 and 90 minutes and physician risk assessment for the presence of ACS. Risk estimates obtained at the time of ED evaluation were dichotomized as high or non-high risk. The primary outcome was the composite of acute myocardial infarction (AMI) or revascularization at 30 days. Logistic regression with receiver operator characteristic (ROC) curves and net reclassification index were used to determine the diagnostic accuracy for the composite outcome of 30-day MI or revascularization for two models: 1) troponin I results and physician risk assessment alone and 2) troponin I results, physician risk assessment, and objective cardiac testing.

RESULTS

A total of 460 women with a median age 58 years (interquartile range [IQR] = 48.5 to 68 years) were included, and 32 (6.9%) experienced AMI or revascularization by 30 days. Comparison of the area under the ROC curves (AUC) showed that the addition of objective cardiac testing to the combination of troponin I results and physician risk assessment did not significantly improve prediction of 30-day AMI or revascularization (AUC = 0.85 vs. 0.89; p = .053). Using a threshold of 1%, net reclassification index showed that the addition of objective cardiac testing to troponin I results and physician risk assessment worsened the prediction for 30-day AMI and revascularization. All of the reclassified patients were false positives, with nine (2.1%) patients incorrectly reclassified from <1% risk to ≥ 1% risk of 30-day AMI or revascularization.

CONCLUSIONS

In the era of contemporary troponin assays, objective cardiac testing after an ED clinician risk assessment of non-high risk and negative troponin I results at 0 and 90 minutes does not improve the prediction of 30-day AMI or revascularization in women presenting with chest pain or other symptoms of cardiac ischemia.

Reduction in observation unit length of stay with coronary computed tomography angiography depends on time of emergency department presentation

OBJECTIVES

Prior studies demonstrating shorter length of stay (LOS) from coronary computed tomography angiography (CCTA) relative to stress testing in emergency department (ED) patients have not considered time of patient presentation. The objectives of this study were to determine whether low-risk chest pain patients receiving stress testing or CCTA have differences in ED plus observation unit (OU) LOS and if there are disparities in testing modality use, based on the time of patient presentation to the ED.

METHODS

The authors examined a cohort of low-risk chest pain patients evaluated in an ED-based OU using prospective and retrospective OU registry data. During the study period, stress testing and CCTA were both available from 08:00 to 17:00 hours. CCTA was not available on weekends, and therefore only subjects presenting on weekdays were included. Cox regression analysis was used to model the effect of testing modality (stress testing vs. CCTA) on OU LOS. Separate models were fit based on time of patient presentation to the ED using 4-hour blocks beginning at midnight. The primary independent variable was testing modality: stress testing or CCTA. Age, sex, and race were included as covariates. Logistic regression was used to model testing modality choice by time period adjusted for age, sex, and race.

RESULTS

Over the study period, 841 subjects presented Monday through Friday. Median LOS was 18.0 hours (interquartile range [IQR] = 11.7 to 22.9 hours). Objective cardiac testing was completed in 788 of 841 (94%) patients, with 496 (63%) receiving stress testing and 292 (37%) receiving CCTA. After age, race, and sex were adjusted for, patients presenting between 08:00 and 11:59 hours not only had a shorter LOS associated with CCTA (p < 0.0001), but also had a greater likelihood of being tested by CCTA (p = 0.001). None of the other time periods had significant differences in LOS or testing modality choice for CCTA relative to stress testing.

CONCLUSIONS

In an OU setting with weekday and standard business hours CCTA availability, CCTA testing was associated with shorter LOS among low-risk chest pain patients only in patients presenting to the ED between 08:00 and 11:59 hours. That time period was also associated with a greater likelihood of being tested by CCTA, suggesting that ED providers may have intuited the inability of CCTA to shorten LOS during other times.

Standardized reporting criteria for studies evaluating suspected acute heart failure syndromes in the emergency department

Heart failure requiring urgent therapy represents a burgeoning health care burden. Although acute heart failure syndromes are commonly defined as a change in chronic heart failure signs and symptoms requiring urgent therapy, the presentation, development, and response to treatment is highly dependent on individual patient characteristics. This heterogeneity has led to challenges in interpreting widely differing study methods, including eligibility requirements and outcome measures. To improve interpretation of results and translate such information to better patient care, it is essential to present an accurate description of the patient population and study design. Based on existing recommendations and expert consensus, the authors present standardized reporting criteria to improve interpretability of research in this challenging cohort.

Identifying patients for early discharge: performance of decision rules among patients with acute chest pain

BACKGROUND

The HEART score and North American Chest Pain Rule (NACPR) are decision rules designed to identify acute chest pain patients for early discharge without stress testing or cardiac imaging. This study compares the clinical utility of these decision rules combined with serial troponin determinations.

METHODS AND RESULTS

A secondary analysis was conducted of 1005 participants in the Myeloperoxidase In the Diagnosis of Acute coronary syndromes Study (MIDAS). MIDAS is a prospective observational cohort of Emergency Department (ED) patients enrolled from 18 US sites with symptoms suggestive of acute coronary syndrome (ACS). The ability to identify participants for early discharge and the sensitivity for ACS at 30 days were compared among an unstructured assessment, NACPR, and HEART score, each combined with troponin measures at 0 and 3h. ACS, defined as cardiac death, acute myocardial infarction, or unstable angina, occurred in 22% of the cohort. The unstructured assessment identified 13.5% (95% CI 11.5-16%) of participants for early discharge with 98% (95% CI 95-99%) sensitivity for ACS. The NACPR identified 4.4% (95% CI 3-6%) for early discharge with 100% (95% CI 98-100%) sensitivity for ACS. The HEART score identified 20% (95% CI 18-23%) for early discharge with 99% (95% CI 97-100%) sensitivity for ACS. The HEART score had a net reclassification improvement of 10% (95% CI 8-12%) versus unstructured assessment and 19% (95% CI 17-21%) versus NACPR.

CONCLUSIONS

The HEART score with 0 and 3 hour serial troponin measures identifies a substantial number of patients for early discharge while maintaining high sensitivity for ACS.

Adenosine stress cardiovascular magnetic resonance-observation unit management of patients at intermediate risk for acute coronary syndrome: a possible strategy for reducing healthcare-related costs

OPINION STATEMENT

Although clear algorithms for diagnosis and treatment of patients with chest pain at low or high risk for an acute coronary syndrome (ACS) exist, they are less well delineated for patients presenting with chest pain with an intermediate risk for ACS. In patients presenting acutely or subacutely to emergency departments (EDs) at high risk for ACS, such as those with ST segment elevation on their 12-lead electrocardiogram (ECG), immediate contrast coronary angiography is performed. On the other hand, chest pain observation units (OUs) are recommended for managing those with chest pain at low risk for an ACS event. In this setting, these OUs are associated with lower healthcare resource utilization and improved cost-effectiveness. Cost-effective diagnosis and treatment options are important goals in healthcare delivery systems. The presentation of patients at intermediate risk for ACS represents an emerging source of resource utilization for EDs. These patients often exhibit pre-existing coronary artery disease, may have sustained prior myocardial infarction, and exhibit multiple comorbidities such as diabetes and hypercholesterolemia. Importantly, however, they will not have evidence of ST elevation on their 12-lead ECG nor will they exhibit serum markers (troponin or creatinine kinase elevations) indicative of ACS. As a consequence of existing co-morbidities, their management becomes time-consuming and may require inpatient monitoring, observation, and cardiac stress testing. Cardiovascular magnetic resonance (CMR) is a powerful tool for risk stratification and prognosis determination in patients in need of stress testing at intermediate risk of ACS. For those who present with acute chest pain syndromes, the combination of CMR in an OU setting represents a potentially attractive option for reducing healthcare-related expenditures without compromising patient outcomes. Recent study results from single centers suggest that CMR-OU care may result in fewer unnecessary hospital admissions and invasive procedures in those presenting with intermediate risk ACS. Further research utilizing stress CMR testing from multiple centers in OU settings is needed to determine if this model of care improves efficiency, reduces healthcare costs, and delivers optimum care in individuals presenting to EDs with chest pain at intermediate risk of ACS.

Cholesteryl esters associated with acyl-CoA:cholesterol acyltransferase predict coronary artery disease in patients with symptoms of acute coronary syndrome

OBJECTIVES

Identifying the likelihood of a patient having coronary artery disease (CAD) at the time of emergency department (ED) presentation with chest pain could reduce the need for stress testing or coronary imaging after myocardial infarction (MI) has been excluded. The authors aimed to determine if a novel cardiac biomarker consisting of plasma cholesteryl ester (CE) levels typically derived from the activity of the enzyme acyl-CoA:cholesterol acyltransferase (ACAT2) are predictive of CAD in a clinical model.

METHODS

A single-center prospective cohort design enrolled participants with symptoms of acute coronary syndrome (ACS) undergoing coronary computed tomography angiography (CCTA) or invasive angiography. Plasma samples were analyzed for CE composition with mass spectrometry. The primary endpoint was any CAD determined at angiography. Multivariable logistic regression analyses were used to estimate the relationship between the sum of the plasma concentrations from cholesteryl palmitoleate (16:1) and cholesteryl oleate (18:1) (defined as ACAT2-CE) and the presence of CAD. The added value of ACAT2-CE to the model was analyzed comparing the C-statistics and integrated discrimination improvement (IDI).

RESULTS

The study cohort was composed of 113 participants with a mean (± standard deviation [SD]) age of 49 (±11.7) years, 59% had CAD at angiography, and 23% had an MI within 30 days. The median (interquartile range [IQR]) plasma concentration of ACAT2-CE was 938 μmol/L (IQR = 758 to 1,099 μmol/L) in patients with CAD and 824 μmol/L (IQR = 683 to 998 μmol/L) in patients without CAD (p = 0.03). When considered with age, sex, and the number of conventional CAD risk factors, ACAT2-CE levels were associated with a 6.5% increased odds of having CAD per 10 μmol/L increase in concentration. The addition of ACAT2-CE significantly improved the C-statistic (0.89 vs. 0.95, p = 0.0035) and IDI (0.15, p < 0.001) compared to the reduced model. In the subgroup of low-risk observation unit patients, the CE model had superior discrimination compared to the Diamond-Forrester classification (IDI = 0.403, p < 0.001).

CONCLUSIONS

Plasma levels of ACAT2-CE have strong potential to predict a patient's likelihood of having CAD when considered in a clinical model but not when used alone. In turn, a clinical model containing ACAT2-CE could reduce the need for cardiac imaging after the exclusion of MI.

CT angiography for safe discharge of patients with possible acute coronary syndromes

BACKGROUND

Admission rates among patients presenting to emergency departments with possible acute coronary syndromes are high, although for most of these patients, the symptoms are ultimately found not to have a cardiac cause. Coronary computed tomographic angiography (CCTA) has a very high negative predictive value for the detection of coronary disease, but its usefulness in determining whether discharge of patients from the emergency department is safe is not well established.

METHODS

We randomly assigned low-to-intermediate-risk patients presenting with possible acute coronary syndromes, in a 2:1 ratio, to undergo CCTA or to receive traditional care. Patients were enrolled at five centers in the United States. Patients older than 30 years of age with a Thrombolysis in Myocardial Infarction risk score of 0 to 2 and signs or symptoms warranting admission or testing were eligible. The primary outcome was safety, assessed in the subgroup of patients with a negative CCTA examination, with safety defined as the absence of myocardial infarction and cardiac death during the first 30 days after presentation.

RESULTS

We enrolled 1370 subjects: 908 in the CCTA group and 462 in the group receiving traditional care. The baseline characteristics were similar in the two groups. Of 640 patients with a negative CCTA examination, none died or had a myocardial infarction within 30 days (0%; 95% confidence interval [CI], 0 to 0.57). As compared with patients receiving traditional care, patients in the CCTA group had a higher rate of discharge from the emergency department (49.6% vs. 22.7%; difference, 26.8 percentage points; 95% CI, 21.4 to 32.2), a shorter length of stay (median, 18.0 hours vs. 24.8 hours; P<0.001), and a higher rate of detection of coronary disease (9.0% vs. 3.5%; difference, 5.6 percentage points; 95% CI, 0 to 11.2). There was one serious adverse event in each group.

CONCLUSIONS

A CCTA-based strategy for low-to-intermediate-risk patients presenting with a possible acute coronary syndrome appears to allow the safe, expedited discharge from the emergency department of many patients who would otherwise be admitted. (Funded by the Commonwealth of Pennsylvania Department of Health and the American College of Radiology Imaging Network Foundation; ClinicalTrials.gov number, NCT00933400.).